Dissertations / Theses: 'Nanofiltration ; Heavy metals ; Adsorption'

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馬依琪 and Yee-ki Ma. "Fractionation, release and adsorption of heavy metals in contaminated marine sediments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227685.

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Evans, Jeffrey Trevor. "Adsorption of heavy metals onto flyash in waste incineration flue gases." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414286.

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De, Haro del Rio David. "Synthesis and characterisation of hierarchical zeolitic materials for heavy metals adsorption." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterisation-of-hierarchical-zeolitic-materials-for-heavy-metals-adsorption(5e4e90db-59b7-4d15-b284-32e179ff1e94).html.

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This thesis explains a method based on the homogenisation of zeta potential charges on carbon supports for the production of hierarchical structured zeolitic composites. The modiﬁcation of carbons’ surface chemistry allowed zeolite particles to be ﬁxed to the support by electrostatic interactions. In order to achieve this, the size reduction of zeolite particles was carried out by two diﬀerent methods: a) ball milling and b) a synthetic route to produce zeolite colloidal dispersions. Also, the seeding method, based on hydrothermal growth was compared. The prepared materials in this work were designed to be used in the sorption of cations, and to allow vitriﬁcation and thereby reduce the ﬁnal adsorbent volume. Results showed that a large pollutant amount can be trapped using a lower volume of material reducing costs and ﬁnal waste disposal. The zeolites used in this work were selected based on their low density framework and low Si/Al ratio. Synthetic zeolites A, Y and clinoptilolite were successfully produced. Natural clinoptilolite was also utilised in this work. Also, zeolite A was produced at nanometre scale following the clear solutions method. All materials were successfully incorporated onto supports to produce multimodal porosity materials. The hierarchical modiﬁcation of natural clinoptilolite, following a straightforward and nonexpensive methodology, is one the most signiﬁcant contributions of this work. Carbons are used as supports due to their high surface area, they can be obtained from low-cost sources such as agroindustrial wastes and carbons allow volume reduction if materials are vitriﬁed at high temperatures. In this work, carbons were produced from corn cob and husk, sugar cane bagasse, cherry stones, date stones and hazelnut shells. The prepared composite materials were tested in the removal of toxic ions from water solutions: cobalt, copper and caesium ions were eﬀectively removed from aqueous media. Adsorption experiments showed that the distribution of supported zeolite particles improved their uptake eﬃciency and capacity. The kinetic studies revealed an enhanced rate constant for carbon-zeolites composites in comparison with pure zeolites. Diﬀusivity results suggested that mass transfer characteristics are modiﬁed by using hierarchical porous materials; results showed that particle size or support nature can modify diﬀusion resistances, reducing intraparticle diﬀusion and accelerating the overall kinetic processes. Adsorption equilibrium data was correlated using Langmuir and Freundlich models.

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Addy, Mary Akuyea. "Modified Organoclay Containing Chelating Ligand for Adsorption of Heavy Metals in Solution." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1372.

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Presence of a chelating ligand in the clay structure significantly improves its ability to immobilize heavy metals from contaminated sludge or wastewater. Two-step modification procedure comprising sequential pillaring and grafting of chelating agent to the modified clay is involved. Montmorillonite and kaolin were chosen as typical examples of expandable and non-expandable clays, correspondingly. Modifications with silica and ferric oxide were targeted on development of mesoporous structure. Laboratory tests of the organoclay efficiency for purification of wastewater were conducted with the most promising sample, i.e. organoclay with the highest specific loading of chelating agent. Experiments were conducted with model wastewater containing either individual or mixed cations of heavy metals. The modified organoclay displayed a high adsorption capacity on heavy metal cations even in acidic media. The method of modification presented in this work can be used for synthesis of efficient adsorbents for applications in contaminated areas.

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Ezzeddine, Zeinab. "Divalent heavy metals adsorption on various porous materials : removal efficiency and application." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2315/document.

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L'accès à l'eau potable est indispensable au développement de la vie. La pollution, liée aux activités anthropiques, constitue une menace pour la santé humaine et pour les espèces sauvages. Parmi les nombreux polluants retrouvés dans les eaux, la pollution par les métaux lourds constitue un problème environnemental d'intérêt mondial en raison de leur toxicité élevée, même à des concentrations très faibles, et de leur persistance dans la nature. De nombreuses méthodes peuvent être mises en oeuvre pour l'élimination des métaux lourds dans l'eau. Parmi elles, les procédés d'adsorption sont très attractifs car très efficaces et peu couteux. Les zéolithes sont des matériaux bien connus pour leurs propriétés d'échange. Les matériaux mésoporeux modifiés ou adsorbants carbonés sont également très attractifs du fait de leur importante surface spécifique. Dans ce manuscrit, les performances d'adsorption de cations métalliques en phase aqueuse sur des matériaux mésoporeux, silices SBA-15, SBA-16, KIT-6 modifiées par l'EDTA et carbone CMK-3 obtenu par réplication ont été étudiées et comparées avec celles de la zéolithe NaX. Les propriétés physico-chimiques de l'ensemble des matériaux ont été caractérisées par plusieurs techniques d'analyses. L'influence des paramètres expérimentaux (pH, temps de contact, température, concentration des ions métalliques et de la présence d'ions concurrents) sur l'adsorption a été étudiée en mode batch. L'efficacité de ces matériaux a également été étudiée dans un réacteur dynamique à lit fixe. Les résultats obtenus ont montré que tous les matériaux étudiés éliminent efficacement et rapidement les métaux divalents dans les eaux même à faible concentration. Néanmoins, le carbone CMK-3 s'avère être le meilleur adsorbant du fait de sa grande capacité d'adsorption même en présence d'espèces compétitrices Access to sustainable and clean drinking water is a main concern as the Earth's human population continues its steady growth. Unfortunately, many of the available water resources are becoming increasingly polluted as a result of the direct discharge of industrial effluents. Heavy metals pollution, in particular, is an environmental problem of global interest due to their high toxicity, even at very low concentrations, and persistence in nature. Many methods are available for metal ions removal including adsorption which is attracting a lot of attention recently. Zeolites are well known for having very high exchange capacities. On the other hand, many researchers are studying the removal of heavy metals by modified mesoporous materials or carbonaceous adsorbents. In this thesis, the adsorption efficiencies of several materials for heavy metal removal in aqueous phase were investigated and compared to those of the faujasite NaX zeolite. Mesoporous silica SBA-15, SBA-16, KIT-6 were synthesized and modified with EDTA. Moreover, CMK-3 carbon was nano-casted from SBA-15 then the physic-chemical properties of these materials were characterized by different techniques. The effects of several experimental conditions on adsorption such as pH, contact time, temperature, metal ions concentration and the presence of competitors were studied in batch experiments. Then the efficiency of all these materials was also studied in a dynamic fixed bed reactor. Based on the obtained results, it could be said that all these materials are good candidates for divalent heavy metals removal from waste water even at low concentration. However, CMK-3 material has a high sorption capacity even in presence of competitor species

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Andersson, Ola. "Adsorption modeling of heavy metals to Sawdust, bark of Pine and Absol." Thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-123164.

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Beaugeard, Marie. "Biosorption of heavy metals by red algae (Palmaria palmata)." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31190.

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The research presented in this thesis entailed an investigation of heavy metal uptake by Palmaria palmata, a red marine alga. The alga was dry and organically certified. The heavy metals of interest were those commonly found in the wastewaters of the printed wiring board industry, namely Cu2+Pb2+, Cd2+, Zn 2+ and Ni2+. The ultimate objective of the work was to determine whether or not the factors expected to influence the metal uptake to the greatest extent could be optimized within functional ranges, leading eventually to process design (beyond the scope of this thesis). These factors were pH, temperature, initial concentration of metal in aqueous solution, and contact time. A number of preliminary experiments were performed to establish a basis for the design of the optimization studies. Although it was not possible to adequately define optimal regions of operation for the biosorption of heavy metals by Palmaria palmata , general trends were elucidated, and the limitations of the methodology used were clarified. (Abstract shortened by UMI.)

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Askari, Hallo Mustafa. "Studies of leaching, recovery and recycling of heavy metals." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/5087.

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The leachability of cadmium, cobalt, copper, lead, nickel and zinc metals and their oxides, sulfides and carbonates by water, 0.5 mol dm-3 CH3COOH, 0.1 mol dm -3 HCl/NaCI (1: 1 mixture) and 2 mol dm -3 HNO3 is reported. The concentrations of the leached heavy metals are compared with the trigger levels set by World Health Organisation (WHO). Three leaching solutions (nitric, sulfuric and hydrochloric acids) were used to extract copper, zinc, cobalt, nickel, iron and lead from spent catalysts prior to the application of separation technologies. Leaching experiments were conducted using both traditional methods and a microwave-assisted extraction technique. Data are provided on the effects of leaching temperature, leaching time, solid to liquid ratio and acid concentration on the extraction of different metals. The use of 2 mol dm-3 sulfuric acid at 50°C for 60 minutes and at a solid/liquid (S/L) ratio of 1: 25 achieved more than 90% extraction for all the metals studied. A comparison of the results from traditional and microwave extraction techniques demonstrates that microwave heating reduced the time required to obtain maximum metal extraction. The kinetics for the traditional extraction procedure showed that diffusion was the ratecontrolling process, but it was not possible to conclusively establish the rate controlling process for the microwave leaching. The feasibility of using an electrodialysis process to separate metal ions, such as copper from zinc, was examined. A laboratory-scale three compartments membrane system was designed, constructed, used and optimised for the separation process. The separation of copper from zinc in the electrodialysis process exploited the greater stability of the Cu-EDTA complex compared with the Zn-EDTA complex. It was observed that Zn 2+ ions migrated through the cation-exchange membrane from central compartment to catholyte and, simultaneously, the negative Cu-EDTA complex transferred to the analyte compartment crossing the anion exchange membrane. The technique was successfully used to separate mixtures of Cu: Cd and Zn: Ni. The technique could not, however, be used for the separation of Zn from Cd. An adsorption process was used to prepare copper, iron, nickel and zinc oxides catalysts on y-A1203 as support. The materials prepared were used in a fixed bed reactor to assess the catalytic oxidation of volatile organic compounds (methane and ethane) in air. Cu/y- A1203 was found to be the most promising catalyst for the complete oxidation of methane and ethane at temperatures of 575°C and 525°C, respectively. Increasing the calcination temperature in the drying and pre-treatment of the catalysts resulted in a decrease in the catalytic activity.

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MacDonald, Elaine. "Aspects of competitive adsorption and precipitation of heavy metals by a clay soil." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26406.

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This thesis examines the retention of three heavy metals (Pb, Cu, Zn) on a predominantly illite clay soil initially saturated with calcium and magnesium. The heavy metal retention mechanisms were examined both experimentally, using batch equilibrium and precipitation tests, and analytically, using the geochemical equilibrium speciation model MINTEQA2. Heavy metal retention was examined in both non-competitive (single metal) situations and competitive (multi-metal) situations. A definite adsorption selectivity order of Pb $>$ Cu $ gg$ Zn was established, as has been found by many other researchers. Retention by ion exchange adsorption was observed by comparing the total amount of heavy metals retained to the total amount of initially adsorbed calcium and magnesium released. In most cases, it was found that ion exchange was the dominant retention mechanism, even at neutral equilibrium pH values. The effect of initial heavy metal solution pH on heavy metal retention was explored. A comparison was made between batch equilibrium tests performed with metal solutions adjusted to an initial pH of 3 and tests performed with metal solutions that were not adjusted and thus at a higher initial pH. In many cases it was found that greater overall retention occurred when initial metal solutions were at a pH of 3 as opposed to a higher initial pH. The speciation modelling, when compared to the experimental results, was found to adequately predict heavy metal retention in simple single metal batch equilibrium tests but in more complicated multi-metal scenarios the modelling had limited success.

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Novicio, Lilibeth Pulido. "CHARACTERIZATION OF CARBONIZED WOOD AND ITS APPLICATION TO THE ADSORPTION OF HEAVY METALS." Kyoto University, 2000. http://hdl.handle.net/2433/181068.

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Kyoto University (京都大学) 0048 新制・課程博士 博士(農学) 甲第8448号 農博第1132号 新制||農||802(附属図書館) 学位論文||H12||N3405(農学部図書室) UT51-2000-F352 京都大学大学院農学研究科森林科学専攻 (主査)教授今村祐嗣, 教授則元京, 教授川井秀一 学位規則第4条第1項該当

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Barquist, Karna Nicole Larsen Sarah C. "Synthesis and environmental adsorption applications of functionalized zeolites and iron oxide/zeolite composites." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/334.

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Bergsten, Joshua. "Sorption and leaching characteristics of heavy metals in artificial soil." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4617.

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Thesis (M.S.) University of Missouri-Columbia, 2006. The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 21, 2007) Includes bibliographical references.

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Zanain, Mabrouk Ali Masaud. "Removal of low concentrations of silver from aqueous solutions using adsorption methods." Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678471.

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Brown, Loren C. "Immobilization of Heavy Metals in Contaminated Soils and Sludge Using Organoclay." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/1178.

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The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring montmorillonite with silica followed by the grafting of a chelate ligand onto its surface. Its structure was studied by the Brunauer, Emmett, and Teller Method adsorption of N2, Dynamic Light Scattering, and Scanning Electron Microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin soil samples and by analysis of heavy metal contents in leachate. The adsorbent was efficient in immobilization of heavy metals in both neutral aqueous and acidic media. In addition, the adsorbent was efficient in environmental samples reducing the concentration of iron in all samples in aqueous and acidic media. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites.

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Barros, Arielle Muniz de. "Bioadsorção e dessorção dos íons 'Cd POT. 2+', 'Cu POT. 2+' , 'Ni POT. 2+', 'Pb POT. 2+' e 'Zn POT. 2+' pela macrófita aquáica Azolla pinnata." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266685.

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Orientadores: Meuris Gurgel Carlos da Silva, Sirlei Jaiana Kleinübing Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Made available in DSpace on 2018-08-21T10:55:13Z (GMT). No. of bitstreams: 1 Barros_ArielleMunizde_M.pdf: 2403867 bytes, checksum: 9d034ece43d77bf5fa23832c79a98b8c (MD5) Previous issue date: 2012 Resumo: Pesquisas no campo da tecnologia têm buscado avaliar técnicas e/ou processos econômicos e eficientes para o tratamento de efluentes que contenham metal pesado. Atualmente a bioadsorção vem se apresentando como uma boa alternativa às tecnologias existentes. Este trabalho teve como objetivo a investigação da macrófita Azolla pinnata como bioadsorvente de cinco íons metálicos: Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+ em soluções sintéticas. A caracterização do biomaterial foi realizada utilizando-se técnicas como Microscopia Eletrônica de Varredura (MEV) para análise da superfície do material; análise de Espectroscopia de Energia Dispersiva de Raios-X (EDX), que mostrou que qualitativamente a diminuição de íons de competição (Ca, Na e K) após o processo de adsorção, evidenciando que a troca iônica pode ser um dos mecanismos do processo; e análise de Infravermelho por Transformada de Fourier (FTIR), em que se pôde constatar que alguns grupos funcionais como carboxilas e grupos sulfonados são fundamentais no processo. A cinética de adsorção foi ajustada pelos modelos de pseudoprimeira e pseudossegunda ordem, sendo que o melhor ajuste variou de acordo com o íon estudado. O modelo de difusão intrapartícula mostrou que muitos mecanismos podem ser limitantes na taxa com a qual ocorre o processo. Os dados de equilíbrio foi ajustado pelos modelos de isoterma de Langmuir e de Freundlich em duas temperaturas, 25 e 45 ºC. O processo foi favorecido pelo acréscimo de temperatura para todos os íons. O modelo de Langmuir se ajustou melhor aos dados experimentais de todos os íons e o valor de capacidade máxima de adsorção (qmax) a 25 ºC foi de 0,359; 0,448; 0,254; 0,472 e 0,357 mmol/g para Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+, respectivamente. Os eluentes HCl, EDTA e CaCl2 foram testados no processo de dessorção em batelada e o cloreto de cálcio se mostrou eficiente além de não causar danos ao material nem diminuir a capacidade de adsorção da macrófita. Ensaios dinâmicos em coluna de leito fixo foram realiados para os íons Cu2+ e Pb2+ com soluções mono e bicomponentes. Nos ensaios em sistema binários, pode-se constatar uma grande preferência pela adsorção de íons chumbo e, portanto, uma grande queda na adsorção de cobre. Foram testados ciclos de adsorção/dessorção em coluna utilizando o CaCl2 como eluente e, em três ciclos, a macrófita manteve suas propriedades adsortivas. Com estes resultados, pode-se constatar que a realização deste trabalho contribuiu para a avaliação deste material como bioadsorvente alternativo e que, especificamente, macrófita A. pinnata mostrou-se atrativa para utilização nos processos de tratamento e/ou estabilização de metais pesados presentes em baixas concentrações em efluentes industriais Resumo: No processo Kraft para produção de papel e celulose, os cavacos de madeira são cozidos em um digestor com uma solução aquosa denominada licor branco, constituída de hidróxido de sódio (NaOH) e sulfeto de sódio (Na2S). Durante o cozimento uma pasta fibrosa é produzida. Esta pasta é filtrada e segue para o branqueamento. O produto filtrado chama-se licor negro, devido à mudança da sua cor nesta etapa. O licor negro possui aproximadamente 15 % de sólidos em massa. Ele é bombeado para a unidade de recuperação, na qual ele será concentrado em evaporadores de múltiplosefeitos até 75 % de sólidos em massa. Em seguida, ele é bombeado para uma caldeira onde é queimado, para recuperar os sais inorgânicos e, principalmente, fornecer calor para geração de calor. Durante a evaporação do licor negro, quando a porcentagem em sólidos ultrapassa 50 %, ocorre a precipitação de sais inorgânicos. Estes sais se depositam nas superfícies de troca térmica dos evaporadores diminuindo sua eficiência e causando prejuízos à indústria. Os principais sais que causam este problema são o carbonato de sódio (Na2CO3) e o sulfato de sódio (Na2SO4). O objetivo do presente trabalho foi testar e validar um método experimental para a determinação da quantidade de Na2CO3 presente em amostras industriais de licor negro. Além disso, também foram analisadas algumas propriedades físico-químicas do licor negro, como massa específica, teor de sólidos e viscosidade. Com os resultados obtidos, tentou-se obter uma correlação entre o teor de carbonato de sódio e as demais propriedades do licor que foram determinadas. Os resultados das análises das características físico-químicas demonstraram coerência e boa reprodutibilidade, porém, os resultados das análises de teor de carbonato de sódio não foram satisfatórios e mostraram que a técnica deve ser aperfeiçoada Abstract: Research in the technology field has been looking for evaluating efficient and economic techniques and/or process for effluents that contains heavy metal. The biodsorption process has been seemed as a good alternative to the existing technology. This work had the aim to investigate the use of Azolla pinnata macrophyte as biosorbent of five metallic ions: Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+ in synthetic solutions. The biomaterial characterization was carried out by techniques as scanning electron microscopy (SEM) for the analyze of material superficies; the energy dispersive X-ray spectroscopy (EDX), which showed, qualitatively, a decreasing in the competitions ions (Ca, Na e K) after the sorption process, indicating that the ion exchange can be one o the process mechanism; and Fourier Transform Infrared Spectroscopy (FTIR), in which it was possible implied functional groups as carboxyl and sulfonate play a important role in the adsorption. The kinetics was adjusted by primer and second order models and the model which fit better depends on each ion. The intra-particle diffusion model showed that several mechanisms may be limiting to the process rate. The equilibrium data were adjusted by Langmuir and Freundlich models in two temperatures: 25 and 45 ºC. The process was favored by the increasing in the temperature for all five ions. The Langmuir model fit better the experimental data and the maximum adsorption capacity (qmax) were 0,359; 0,448; 0,254; 0,472 and 0,357 mmol/g for Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+, respectively. The HCl, EDTA and CaCl2 eluents were tested in the desorption process and the calcium chloride was efficient and did not cause any damage in the biomaterial or decreasing the biosorption capacity. Dynamics runs were carried out in fixed-bed in mono and bi-components solutions. In the binary were found a great preference for lead instead of copper and as a result, a significant decrease in the removal of copper. Adsorption/desorption cycles were tested in fixed-bed system using CaCl2 as eluent. After three cycles no damage, weight lost or significant decrease in the biosorption capacity was noticed. These results indicating that the A.pinnata macrophyte is an attractive potential new biosorbent to be used in heavy metal removal especially in low concentrations effluents Abstract: In the Kraft process for pulp and paper production, wood chips are cooked in a digester with an aqueous solution named white liquor, consisted by sodium hydroxide (NaOH) and sodium sulfide (Na2S). During this cooking process, wood chips are transformed generating a fibrous paste and a liquid solution. This paste is filtered and separated from the liquid solution, named black liquor due to its color. The paste goes to the bleaching stage to produce cellulose. Black liquor contains inorganic and organic (mainly lignin) compounds from wood. Initially this black liquor contains approximately 15 mass/% of solids and is sent to the recovery unit to have this concentration raised to approximately 75 mass/% to be burned in a recovery boiler in order to generate power and recover inorganic reactants, recycling them to the process. The concentration process of black liquor occurs in a multiple effect evaporators unit. During this process, when the concentration of solids exceeds 50%, the precipitation of inorganic salts (mainly Na2CO3 and Na2SO4) begins. These salts are deposited in the heat transfer surfaces of the evaporator tubes, reducing their efficiency, leading to a reduction in the production capacity. The scope of this work was testing and validate an experimental method to estimate the content of Na2CO3 present in industrial black liquor samples. Moreover, some black liquor's physical-chemical properties as density, solids content and viscosity were also analyzed. An attempt to develop a predictive model to evaluate sodium carbonate content from the other properties was made. The results obtained for physical-chemical properties have shown a good consistency. However, the results of sodium carbonate analyses were not satisfactory, showing that the technique must be improved Mestrado Engenharia de Processos Mestra em Engenharia Química

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Brown, Pauline Anne. "The application of peat and lignite to the removal of heavy metals from industrial wastewater." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360482.

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Barquist, Karna Nicole. "Synthesis and environmental adsorption applications of functionalized zeolites and iron oxide/zeolite composites." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/334.

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Silicalite-1 crystals and hollow tube structures were synthesized and functionalized with amine and sulfur containing groups. The adsorption behavior of metal ions (Pb2+, CrO4-) in aqueous solution was investigated on nanocrystalline zeolites functionalized with amines and thiols. Nanocrystalline zeolites with a diameter of 30-50 nm and external surface areas around 100 m2/g were functionalized with 3-aminopropyltriethoxysilane (3-APTES) and 3-mercaptopropyltrimethoxysilane (3-MPTMS). The materials were characterized by 29Si magic angle spinning nuclear magnetic resonance spectroscopy and x-ray diffraction. The adsorption of metal ions from aqueous solutions of Pb (NO3)2 and Na2Cr2O7 was measured by inductively coupled plasma-atomic emission spectroscopy. The effects of various conditions such as pH and concentration were studied to optimize adsorption. Adsorption on functionalized mesoporous silica (MS) was conducted for comparison to the functionalized zeolites. Magnetic zeolite/iron composites were prepared using nanoscale and commercial faujasite zeolites. The composites were functionalized with amine groups to facilitate chromate adsorption under acidic conditions. The materials were characterized using nitrogen adsorption, scanning electron microscopy, thermogravametric analysis, FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of chromium was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution chromium quantitatively. The removal of the composites with a magnet was demonstrated. The materials were then evaluated for the adsorption of Cr6+ using ICP-OES to detect chromium. Iron containing zeolite composites were prepared using nanoscale faujasite zeolites. The composites were functionalized with amine groups and Fe ions to facilitate arsenate(As V) adsorption under a variety of pH conditions. The materials were characterized using nitrogen adsorption, X-ray diffraction, thermogravametric analysis and FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of arsenic was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution concentration quantitatively. The removal of the composites with a magnet was demonstrated. Kinetics and pH dependence of the adsorption were studied.

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Tuzcu, Emrah Tugcan. "Removal Of Heavy Metals In Waste Water By Using Coal Fly Ash." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606366/index.pdf.

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In this research, it is aimed to remove toxic heavy metals in waste water with the help of fly ash from &Ccedil ayirhan thermal power plant. The chemical and physical properties (size distribution, specific surface area, porosity, chemical composition, etc.) of fly ash were determined. The experiments were carried out in synthetic waste water containing lead, zinc and copper metals at different concentrations with the addition of fly ash. The effects of metal concentration, agitation time, particle size, ash amount, and pH in the metal removal were examined. With the addition of even very small amount of fly ash, heavy metal removal from waste water was attained at up to 99%. Fly ash particle size has no significant effect on removal of heavy metal ions from solutions. Higher solution pH and longer treatment time were resulted better metal removal. The results also indicated that the main mechanism for metal removal was precipitation due to alkaline characteristics of fly ash and more than 90 % of metals in solutions were removed by precipitation. The pH ranges for maximum metal precipitation were 10-11, 8-10, and 10-11 for copper, zinc, and lead respectively. Very small percentages of adsorbed metal was released during the desorption test.

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Selepe, Mamaropeng Marcus. "The removal of toxic heavy metals from aqueous solutions by algal extracellular polysaccharides." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1004054.

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This study investigated the possible use of algal extracellular polysaccharide as a biosorbent for removal of heavy metals (copper and lead) from aqueous solutions as a means of bioremediation for metal containing effluents. This biopolymer has good biosorbent properties and a potential to provide a cost effective, selective and efficient purification system. A variety of environmental conditions induce the production of extracellular polysaccharides in algae. The production of exopolysaccharides by Dunaliella cultures was induced by nitrogen deficient conditions. A high ratio of carbon to nitrogen source considerably enhanced the polysaccharide release. Purified extracellular polysaccharide samples exhibited a monosaccharide composition consisting of the following sugars: xylose, arabinose, 2-0-methyl mannose, mannose, glucose and galactose. The relative abundance (%) of these sugars were calculated relative to xylose. The major sugar constituent was 2-0-methyl mannose, which was present at approximately 160% relative to xylose. The percentage relative abundance of other sugars was as follows: 18.8; 86.8; 85.3 and 22.3% for arabinose; mannose; glucose and galactose respectively. The identity of the various constituents were confirmed by mass spectrometry. The ability of Dunaliella exopolysaccharides to accumulate metals was investigated. The following parameters were studied because they affect metal uptake: solution pH, biomass concentration, temperature, time and metal concentration. The uptake of both copper and lead were pH dependent. However, metal uptake was not significantly affected by temperature. Kinetic studies showed that Dunaliella extracellular polysaccharides exhibit good bioremediation properties. Metal uptake was rapid. In addition, the exopolysaccharide has good metal binding capacity with an uptake capacity for lead of 80 mg/g from a solution containing initial lead concentration of approximately 40 mg/l. Competition studies revealed that the presence of a second metal in solution inhibits uptake of the other metal compared to uptake in single metal solution of that particular metal. The presence of lead inhibited the uptake of copper from approximately 65% in single metal solution to 10% in binary metal solution. The presence of copper also inhibited lead uptake, though not to the same extent. Higher concentrations of lead could not completely prevent removal of copper from solution and visa versa. The same was true for lead which could not be displaced by a four-fold concentration of copper. Instead, a certain percentage of copper was always removed showing that lead did not compete with copper for these binding sites. In conclusion it appears that, copper and lead bind to different sites on Dunaliella exopolysaccharides and that they exhibit selective or preferential removal of lead.

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26

Darko, Godfred. "Pre-concentration of heavy metals in aqueous environments using electrospun polymer nanofiber sorbents." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1004998.

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This thesis presents an alternative approach for pre-concentrating heavy metals in aqueous environments using electro spun polymer nanofiber sorbents. The conditions for electrospinning polyethersulfone, polystyrene, polysulfone and polyamide-6 were optimized. The morphologies and porosities of the electrospun nanofibers were studied using SEM and BET nitrogen gas adsorptions. The nanofibers had mesoporous morphologies with specific surface areas up to 58 m2/g. The electro spun nanofiber sorbents were characterized in terms of their tunability for both uptake and release of heavy metals. The usability of the sorbent was also assessed. The sorbents showed fast adsorption kinetics for heavy metals « 20 min for As, Cu, Ni and Pb) in different aqueous environments. The adsorption characteristics of the sorbents best fitted the Freundlich isotherm and followed the first order kinetics. The efficiencies of adsorption and desorption of heavy metals on both imidazolyl-functionalized polystyrene and amino-functionalized polysulfone sorbents were more than 95% up to the fifth cycle of usage. Reusability improved dramatically (up to 10 runs of usage) when mechanically stable amino-functionalized nylon-6 electro spun nanofibers were used. The capacity of the amino-functionalized nylon-6 sorbent to pre-concentrate heavy metals compared very favourably with those of aqua regia and HN03+H202 digestions especially in less complex matrices. Due to their highly porous nature, the electro spun nanofibers exhibited high adsorption capacities (up to 50 mg/g) for heavy metal ions. The loading capacities achieved with the imidazolyl-functionalized sorbent were higher than those for amino-functionalized mesoporous silica and biomass-based sorbents. The electro spun nanofiber sorbents presents an efficient and cost effective alternative for preconcentrating heavy metals in aqueous environments.

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27

Osifo, Peter Ogbemudia. "The use of chitosan beads for the adsorption and regeneration of heavy metals / Peter Ogbemudia Osifo." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1635.

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28

Kothalawala, Kothalawalage Nuwan. "Nanoporous high surface area silicas with chelating groups for heavy metal ion adsorption from aqueous solution /." View online, 2010. http://repository.eiu.edu/theses/docs/32211131524422.pdf.

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29

Heinrich, Hannah Tabea Monika, and n/a. "Acid-base and Cd�⁺ adsorption properties of two thermophilic bacteria." University of Otago. Department of Chemistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20080107.095128.

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The release of toxic metal species is of concern due to their detrimental effects on the environment and human health. Industrial effluents are a major source of mobilised metal species. Suitable technologies are needed to sequester toxic metal species at the point of source. Biosorption, which is based on the passive adsorption of contaminants onto biological materials, promises to offer an effective alternative or complementary step to existing treatment methods. However, to date there has been no widespread commercialisation of the technique. This is partly due to an insufficient understanding of the complex underlying mechanisms which makes it difficult to select suitable biomass for specific remediation problems and to predict process performance. This study characterised two gram-positive, thermophilic bacteria, Anoxybacillus flavithermus (BF) and Geobacillus stearothermophilus (BS), harvested at two different growth times, with regard to their acid-base and Cd�⁺ adsorption behaviour. The aim was to investigate the metal cation adsorption properties of thermophilic bacteria which has not been studied previously, and to gain a better understanding of the interactions responsible for bacterial metal cation adsorption. Experimental techniques employed in this study included microscopy to establish cell and cell wall morphology, batch acid-base and Cd�⁺ adsorption experiments to quantify proton active surface functional groups and Cd�⁺ adsorption, electrophoretic mobility measurements to assess the overall surface charge of the bacteria and in situ attenuated total reflection infrared (ATR-IR) spectroscopy to reveal the chemical identities of functional groups. Chemical equilibrium models based on batch acid-base titration and electrophoretic mobility data were developed to quantitatively describe proton active surface functional groups. These groups can also interact with metal cations. It was found that growth time was an important factor in all experiments with the differences between growth times often being more pronounced than the differences between the two bacterial strains. Microscopy revealed a gram-positive cell wall structure with different widths and staining behaviour for exponential phase cells of BF and BS. Stationary / death phase cells showed disintegrating cell walls. Acid-base titrations indicated that all cells possessed buffering capacity over the whole investigated pH range (pH 2 - 10). From electrophoretic mobility measurements, isoelectric points of ~ 3.2 for BF and < 1.8 and ~ 4.2 for exponential and stationary / death phase cells of BS respectively were estimated. Chemical equilibrium models including a Donnan electrostatic model were derived which described both the batch acid-base titration data and the electrophoretic mobility data reasonably well, although a comparison with IR data suggested room for further improvement. In situ ATR-IR spectroscopy of hydrated bacterial cells at various pH values revealed amide and carboxyl groups and a contribution from phosphate / polysaccharide moieties. Group specific interactions with Cd�⁺ were not detected, however, a partially reversible absorbance increase of all peaks suggested conformational changes in the presence of Cd�⁺. BF and BS adsorbed ~ 70 [mu]mol Cd�⁺ (g dry bacterial)⁻� at pH 5 in 0.01 M NaNO₃. Release of major cations occurred concomitantly with Cd�⁺ adsorption. The buffering and Cd�⁺-binding capacities of BF and BS were found to be comparable to those of mesophilic bacteria and ion exchange was identified as an important adsorption mechanism.

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30

Ogunleye, Adetoro O. "Bacterial poly-gamma-glutamic acid (γ-PGA) : a promising biosorbent of heavy metals". Thesis, University of Wolverhampton, 2015. http://hdl.handle.net/2436/579925.

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Poly-γ-glutamic acid (γ-PGA) is a biopolymer made up of repeating units of L-glutamic acid, D-glutamic acid or both. γ-PGA is water soluble, non-toxic and biodegradable, and can be used safely in a variety of applications that are increasing rapidly. This study investigated the production of HMW γ-PGA by five Bacillus species (B. licheniformis 1525, B. licheniformis NCTC 6816, B. licheniformis ATCC 9945a, B. licheniformis ATCC 9945a and B. subtilis (natto) ATCC 15245) in GS, C and E media for the removal of heavy metals in wastewaters. The highest γ-PGA yields of 11.69 g/l and 11.59 g/l were produced by Bacillus subtilis (natto) ATCC 15245 in GS medium and medium C respectively. Upon characterization, γ- PGAs with different properties (crystallinity, acid/salt form and molecular weights ranging from 2.56 × 105 Da to 1.65 × 106 Da) were produced. The water soluble, non-toxic, HMW (Mw 1.65 × 106 Da) γ-PGA produced by B. subtilis (natto) ATCC 15245 in medium C was investigated as a sorbent for the removal of heavy metal ions including Cu2+, Zn2+, Ni2+, Cd2+ and Ag+. The results showed that the removal of metals by γ-PGA was more dependent on the concentration of γ-PGA than the solution pH. The highest metal ions removal of 93.50%, 88.13%, 90.21%, 90.56% and 86.34% by HMW γ-PGA were obtained for Cu2+, Zn2+, Ni2+, Cd2+ and Ag+ respectively. The presence of interfering metal ions could hinder the adsorption of individual metal ions by γ-PGA. The affinities of heavy metal ions for γ-PGA followed the order: Cu2+ > Zn2+ > Ni2+ > Cd2+. The effect of molecular weight of γ-PGA on metal removal was also investigated, and it was found that metal ion adsorption capacity of γ-PGA strongly depended on its molecular weight. The maximum amount (93.50%) of Cu2+ sorbed by HMW γ-PGA was higher compared to that (59.48%) sorbed by LMW γ-PGA. Isotherm models showed that the Redlich-Peterson best described the metal adsorption capacity of γ-PGA. It was also found that a multisite adsorption mechanism occurred via the complexation of metal ions with the free α-carboxyl and possibly the amide functional groups in γ-PGA.

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31

Dietrich, Theo Henry. "The removal of heavy metals from dilute aqueous streams by the use of ion exchange resins." Thesis, Cape Technikon, 1998. http://hdl.handle.net/20.500.11838/887.

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Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 1998 Ion exchange resins are widely used to remove or concentrate heavy metals from aqueous solutions or slurries.This thesis attempts to properly evaluate the interaction between ion exchange resins and heavy metals at trace metal concentrations.The durability of the resins and their effectiveness in real slurries were also investigated. In this study, a chelating resin, as well as a cation, and anion exchange resin was contacted with aqueous solutions of heavy metals in both free and complexed form. Zinc, nickel and copper cyanide complexes were adsorbed onto the anion exchange resin, while the chelating and cation exchange resins were contacted with zinc and nickel nitrates, and cupric sulphate. All the tests were conducted in batch stirred tank reactors. All the metal cyanide complexes behaved in a similar manner when contacted with the anion exchange resins. These tests were p~rf0nned under variations in temperature, stirring speed, pH., ionic strength and . initial metal 90E~entrations. Fitting of a dual resistance model to the profiles for thetlptllk:e" of the complexes, show that both film diffusion and intraparticle diffusion rates were improved with an increase in temperature, and that film diffusion rates improved with an increase in stirring speed. A high ionic strength negatively affected equilibrium loading as well as diffusional rates.It was found that at these low concentrations, the diffusional rates improves with a decrease in the external metal concentration. A comparative study involving the chelating and cation·exchange resins were performed, during which the resins were contacted with the metals in free fonn. It was found that at high metal concentrations, the chelating resin induced a rate limiting effect, but at trace concentrations, this effect is virtually negated. Whereas the cation exchange resin exhibited little selectivity in adsorbing the metals, it was found that the chelating resin prefers the metals in the eu > Ni > Zn. The chelating resin proved to be no less durable then the cation exchange resin, and both slightly lost their ability to adsorb the metal cations as a result of the effects of an inert coarse sand slurry.Tests performed with a real ore leachate, showed the cation exchange resin to be efficient at a low pH , but also relatively non selective, since the adsorption of copper from the leachate was greatly reduced due to the presence of other heavy metals.

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32

Gaona, Galindo Luz Stella. "Remoção de íons de chumbo e cádmio em diferentes sistemas de adsorção/troca iônica em argila bentonítica tipo Fluidgel." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266715.

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Orientadores: Melissa Gurgel Adeodato Vieira, Ambrósio Florêncio de Almeida Neto Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Made available in DSpace on 2018-08-21T04:22:05Z (GMT). No. of bitstreams: 1 GaonaGalindo_LuzStella_M.pdf: 4431618 bytes, checksum: c30f71e68b49dd362a3ed8f70bde5a0a (MD5) Previous issue date: 2012 Resumo: Neste trabalho foi avaliada a capacidade de remoção de metais pesados comumente encontrados em efluentes e aterros sanitários da região metropolitana de Campinas, mais especificamente o chumbo e o cádmio, utilizando argila bentonítica sódica tipo Fluidgel extraída de jazias do nordeste brasileiro (Boa Vista - PB). A argila Fluidgel foi fornecida na forma comercial, composto de argila natural com a adição de carbonato de sódio. A argila Fluidgel comercial foi submetida a um tratamento ácido, uma vez que o pH natural desta ocasionava precipitação química do chumbo e do cádmio, sendo denominada Fluidgel TA. A argila Fluidgel comercial foi submetida ao tratamento térmico e químico por um período de 24 horas a temperatura de 750 ºC, com o objetivo de melhorar sua estabilidade física, sendo denominada Fluidgel TACal. As técnicas empregadas para a caracterização das argilas visando informações importantes para conhecer a viabilidade das suas propriedades na remoção de metais foram realizadas por termogravimetria (TG), calorimetria exploratória (DSC), difração de raios-X (DRX), espectroscopia de infravermelho (FTIR), área superficial, picnometria a gás hélio, microscopia eletrônica de varredura (MEV)/(EDS) e capacidade de troca catiônica (CTC). As técnicas de remoção estudadas neste trabalho foram a de banho finito e de leito fixo, permitindo avaliar os mecanismos e taxas de remoção dos íons de chumbo e cádmio, a partir da realização de curvas de equilíbrio e cinéticas de cada íon. A adsorção de Cd2+ e Pb2+ foi estudada em sistema estático e dinâmico para as argilas Fluidgel TA e Fluidgel TACal. A argila Fluidgel comercial não foi utilizada no processo de adsorção destes metais, já que seu alto teor de carbonatos ocasionou a precipitação química, além de não apresentar resistência mecânica adequada para aplicação posterior em sistema dinâmico de leito fixo. Os ensaios monocomponentes em sistema estático e dinâmico mostraram que o chumbo tem maior afinidade pelos sítios das argilas. Verificou-se a partir dos resultados obtidos em banho que as quantidades máximas adsorvidas pela argila Fluidgel TA foram de 0,038 e de 0,035 mmol de metal/g de argila, para o cádmio e o chumbo respectivamente. Utilizando argila Fluidgel TACal a quantidade máxima adsorvida de cádmio não foi significativa (0,005mmol/g), sendo para o chumbo de 0,033 mmol de metal/g de argila, podendo-se observar que a capacidade de remoção foi reduzida devido ao tratamento térmico. A partir das curvas de ruptura obtidas nas diferentes vazões verificou-se os diferentes comportamentos, indicando a forte influência da vazão nas resistências difusionais, mostrando que na vazão de 1 mL/min foi obtido um valor baixo de comprimento da ZTM (3,413), bem como uma baixa resistência à transferência de massa para a remoção de chumbo pela argila FluidgelTACal. Para regeneração dos leitos de argila FluidgelTACal foi utilizado o CaCl2 como eluente. A remoção do chumbo obtida até saturação do leito de argila FluidgelTACal, no primeiro ciclo foi de 0,03782 mmol/g, diminuindo no segundo e terceiro ciclos (0,02478 e 0,02060 mmol/g) Abstract: This study aimed to evaluate the ability to remove heavy metals commonly found in industrial wastewater and landfills in the metropolitan region of Campinas, specifically lead and cadmium using as adsorbent sodic bentonite clay type Fluidgel, which was obtained from Boa Vista, Paraíba, located in the northeastem region of Brazil. Fluidgel was provided as a commercial product processed, being composed of natural clay with sodium carbonate addition. Fluidgel in nature was subjected to acid treatment because the pH of this clay occasioned chemical precipitation of lead and cadmium, it was named Fluidgel TA. In order to improve the physical stability, the Fluidgel clay was also carried out a chemical and thermal treatment for a period of 24 hours at 750 oC and it was named as Fluidgel TACal. The techniques employed for the characterization of clays seeking important information to identify the viability of their properties in the removal of metals and it was performed by thermogravimetry, scanning calorimetry, X-ray diffraction (XRD), Fourier transform infrared (FTIR), Thermal Analysis (TG and DSC), Scanning Electron Microscopy (SEM) with chemical analysis by Energy Dispersive X-ray (EDX), surface area, helium pycnometry, and cation exchange capacity. The removal techniques discussed in this work were realized in the finite bath and fixed bed with the purpose to evaluate the mechanisms and removal rates of lead and cadmium. The adsorption of Cd2+ and Pb2+ was studied in the finite bath and fixed bed systems using Fluidgel TA and Fluidgel TACal. Fluidgel was not used in the process of adsorption of these metals, due to their high content of carbonates caused the precipitation chemistry, besides it type of clay did not has mechanical strength suitable for application in dynamic system of fixed bed. According to obtained results, sorption affinity of clays towards lead is larger than their affinity towards cadmium. The results obtained in a finite bath showed that the maximum amount adsorbed by the clay Fluidgel TA was 0.038 and 0.035 mmol of metal/g of clay, for cadmium and lead, respectively. Using clay Fluidgel TACal the maximum amount of adsorbed cadmium was not significant (0.005 mmol / g), whereas for lead was of 0.033 mmol of metal / g of clay, can be observed that the removal capacity has been reduced due to heat treatment. Fixed bed experiments were developed evaluating the breakthrough curves obtained by different flow rates showed different behavior, indicating a strong influence on the flow rate of diffusional resistance, can observed that using the flow rate of 1 mL/min was obtained a low value of the length of the mass transfer zone (MTZ) of 3.413 and moreover, a low resistance to mass transfer to remove lead with Fluidgel TACal clay. The CaCl2 was used as eluent with the purpose to regeneration of the beds using Fluidgel TACal clay. The study conducted in fixed bed system for lead in cycles of adsorption/desorption showed that in the first cycle was 0.03782 mmol/g, reducing the second and third cycles (0.02478 and 0.02060 mmol /g) Mestrado Processos em Tecnologia Química Mestra em Engenharia Química

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33

Thompson, Denis Alan. "Removal of copper and nickel from solution by the non-viable biomass of the water fern Azolla filiculoides in an upscaled fixed-bed column system." Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1003973.

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The potential of non-viable Azalia filiculaides for the removal of Cu and Ni from aqueous solutions and the possibility of scaling up existing lab scale Azalia column systems was investigated. The effects of factors such as metal starting concentration, pH and two metals in solution on the removal of Ni and Cu from aqueous solution by dried and crushed Azalia biomass were studied in batch systems. Aqueous solutions of Ni with starting concentrations between 1000 and 2000J.lmolll gave the most efficient Ni removal by Azalla biomass. For Cu the optimum starting concentration for adsorption was 50J.lmol/l. The adsorption capacity of both eu and Ni increased as the starting pH of the sorption media increased. The optimum pH for Ni adsorption was found at pH 7 and for Cu, at pH 5. - Awlla biomass had a higher. maximum binding capacity (qrnax) for Cu than for Ni at pH 5. The removal of both Cu allct Ni showed little or no variation with the presence another metal in solution. Kinetic studies show that both Cu and Ni adsorbed rapidly onto the Azalia biomass. The removal of Cu and Ni from aqueous solutions using non-viable Azalia biomass was investigated in a lab scale fixed-bed column and an upscaled 4L column system. The nonviable Azalla filiculaides biomass when dried and used in a column for adsorption of Cu and Ni showed good physical stability under many different conditions. Preparation of the biomass before it could be used in the columns was very simple and did not involve any significant pretreatment steps. Prolonged exposure to UV light decreases Azalia biomass capacity for Ni and Cu adsorption. Column adsorption of Cu and Ni from aqueous solutions was successfully upscaled approximately 100 times. Relative to the lab scale column, the 4L column performed better for the uptake of Cu and Ni per gram of biomass. The larger column was also able to operate at relatively higher flow rates. The biomass showed good reusability with little change in the amount of Ni adsorbed in 10 consecutive cycles. Electron micrographs showecf little or no change in the physical structure and integrity of the Azolla biomass after exposure to mineral acids, Ni solution and high flow rates over 10 consecutive adsorption and desorption cycles. As much as 80% Ni and 70 % Cu was recovered when desorption profiles were generated using O.lMHCI as a desorption agent. The 4L column system was also tested using a highly concen~rat:~ Ni plating bath solution.(Nicrolyte 1). Only 18 % of the Ni could be removed from the expended Nicrolyte 1 pla~Jng solution after treating only 25L, indicating that Azolla biomass is more suited for removal of metals from more dilute industrial effluents.

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34

Ntuli, Themba Dominic. "Preparation of chemically modified Macadamia nutshells for adsorptive removal of selected heavy metals." Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/379.

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M. Tech. (Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology The abundance of agricultural waste materials has led to its use as adsorbents for trace metal adsorption. The raw Macadamia nutshell (RMN) powder was treated with a hydrochloric acid solution to obtain acid modified Macadamia nutshells (AMM), and with sodium hydroxide solution to obtain base modified Macadamia nutshells (BMM). Then, the AMM and BMM materials were grafted with 0.5 M, 1 M, and 2 M acrylic acid. The different AMM grafted materials were labelled 0.5 GAM, 1 GAM and 2 GAM representing the different grafting ratios. The same naming order was followed for the BMM grafted materials, that is, 0.5 GBM, 1 GBM and 2 GBM corresponding to different concentrations used. The prepared Macadamia based adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), carbon, hydrogen, nitrogen and sulphur (CHNS) analysis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis. The determination of surface properties such as the point of zero charge (pHPZC), bulk density and the surface negative charge was accomplished with appropriate wet chemistry methods. The adsorption of selected trace metals (Cu(II), Cd(II), Co(II), and Cr(VI)) was done in batch experiments. Atomic absorption spectroscopy (AAS) was used for the determination of metal ions concentrations and total Cr. The ultraviolet-visible (UV–Vis) spectroscopy was used for the determination of Cr(VI) concentration remaining in solution after adsorption. The RMN, AMM, and BMM adsorbents showed potential in removing more than 45% Cu(II) ions, but less than 30% for both Cd(II) and Co(II) ions. However, more than 90% removal of Cr(VI) ions was achieved with the same adsorbents. Consequently, only the adsorption of Cr(VI) was further investigated in the study due to the higher removal efficiency displayed by the Macadamia based biosorbents. The optimum adsorption conditions for the RMN, AMM, and BMM materials were found to be pH 2, 100 mg/L initial concentration of Cr(VI), 600 min contact time and 0.2 g adsorbent mass. The ideal conditions for the 0.5 GAM and 0.5 GBM were found to be pH 2, 25 mg/L initial concentration of Cr(VI), 180 min contact time, and 0.15 g adsorbent mass. The optimum temperature was found to be 40℃ for all materials. A volume of 20 mL was used for all batch experiments. The RMN, AMM, BMM, 0.5 GBM, and 0.5 GAM adsorption mechanisms were better described by the Langmuir isotherm which predicted a monolayer sorption process. The kinetic data fitted better to the pseudo second-order rate model which signified a chemisorption type of interaction. The thermodynamic parameters showed that the adsorption reaction was feasible, spontaneous and endothermic. The Macadamia based materials showed greater potential as adsorbents for the adsorption of Cr(VI) ions from aqueous solution compared to the other selected trace metal ions [Cd(II), Cu(II) and Co(II)].

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35

Deng, Hong. "Metal (Pb, Zn, Cu, Cd, Fe) uptake, tolerance and radial oxygen loss in typical wetland plants." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/629.

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36

Silva, Adrielli Cristina Peres da. "Funcionalização do PVC para aplicação em procedimentos de extração em fase sólida de espécies metálicas." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153661.

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Submitted by Adrielli Cristina Peres da Silva (adriellicristina@hotmail.com) on 2018-04-20T19:17:40Z No. of bitstreams: 1 DISSERTAÇÃO ADRIELLI CRISTINA PERES DA SILVA - BIOTECNOLOGIA.pdf: 1253086 bytes, checksum: 7537e0e126ba2d997c618f87745823e5 (MD5) Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2018-04-23T12:53:53Z (GMT) No. of bitstreams: 1 silva_acp_me_bot.pdf: 1253086 bytes, checksum: 7537e0e126ba2d997c618f87745823e5 (MD5) Made available in DSpace on 2018-04-23T12:53:53Z (GMT). No. of bitstreams: 1 silva_acp_me_bot.pdf: 1253086 bytes, checksum: 7537e0e126ba2d997c618f87745823e5 (MD5) Previous issue date: 2018-02-21 Pró-Reitoria de Pós-Graduação (PROPG UNESP) O desenvolvimento de materiais adsorventes e posterior utilização em procedimentos de extração em fase sólida (remoção/ pré-concentração) de espécies metálicas é uma área da Química/ Engenharia Química, que sempre se manteve em destaque devido à necessidade, seja de monitorar, realizar a remoção da matriz antes da análise ou de remover o contaminante da amostra. A determinação direta de metais presentes em baixas concentrações em amostras de águas naturais é geralmente dificultada devido à presença de espécies interferentes e à necessidade do uso de técnicas sofisticadas para quantificá-los. Os metais determinados: Cu(II), Cd(II), e Pb(II); são de interesse ambiental em razão de seu uso intensivo, distribuição e por serem não-degradáveis, podendo acumular-se em matrizes ambientais manifestando toxicidade. Desta forma, o projeto teve como objetivo a utilização do PVC como suporte sólido para o ancoramento da molécula 4-amino-3-hidrazino-5-mercapto-1,2,4-triazol (AHMT) e aplicação em sistema de pré-concentração e remoção de espécies metálicas em amostras aquosas. O material foi caracterizado por Análise Elementar, a qual determinou a concentração do ligante por meio da porcentagem de nitrogênio, que foi de 3,88%. Espectroscopia de infravermelho por transformada de Fourier (FTIR) que constou a presença de bandas em 3200 cm-1 e entre 3300 e 3500 cm-1 que podem ser atribuídas ao grupamento amina, presente na molécula do ligante, cujos resultados podem ser indicativos de que a funcionalização ocorreu com sucesso. Espectroscopia de Fotoelétrons Excitados por Raios-X que corroborou as análises anteriores indicando a presença de grupos referentes ao ligante. Medidas da área superficial específica pelo método BET a qual caracterizou o material segundo a Isoterma de adsorção/ dessorção do Tipo II, Microscopia Eletrônica de Varredura (MEV) e Determinação de Ponto de Carga Zero (pHpzc), para a verificar a ocorrência da reação de modificação e possibilitar a construção de um modelo. O material foi aplicado em estudos de adsorção para se determinar o tempo mínimo de contato, o pH ótimo de adsorção e a sua Capacidade Máxima de adsorção, no qual constatou 0,46; 0,14 e 0,32 mmol g -1 para Cu(II), Cd(II) e Pb(II), respectivamente. Na sequência, o material foi aplicado em sistema de fluxo contínuo para otimização de parâmetros, tais como: 18 Massa da amostra e vazão de percolação da solução, concentração do eluente e volume do eluato. The development of adsorbent materials and subsequent use in the phase extraction processes (preconcentration) of metallic species is an area of Chemistry / Chemical Engineering that has always attracted great attention in virtue of the need to monitor contamination and to perform matrice-analyte separation prior to analysis. The direct determination of metals present at low concentrations in samples of natural waters is difficult due to the presence of interfering species and to the need of sophisticated techniques to quantify them. The metals, Cu(II), Cd(II) and Pb(II) have environmental interest because of their intensive use, distribution and because they are non-degradable, thus accumulating in the environment and manifesting toxicity. Thus, the objective of the project was to use PVC as a solid support for the anchoring of the molecule 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) and its application in a system for the preconcentration and removal of metal species from aqueous samples. The material was characterized by Elemental Analysis, Fourier-transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy, specific surface measurements according to BET method, Scanning Electron Microscopy (SEM) and Point of Zero Charge (pHpzc) to verify the occurrence of the modification reaction and to enable the construction of a model.The material was applied in adsorption studies to determine the minimum contact time, the optimum adsorption pH and its maximum adsorption capacity, in which it found 0.46; 0.14 and 0.32 mmol g-1 for Cu (II), Cd (II) and Pb (II), respectively. Then, the material was applied in a continuous flow system, to optimize parameters such as: sample mass, sample percolation flow, eluent concentration and eluate volume; in order to apply, posteriorly, in natural water samples. 33004064087P8

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Somasani, Swarna Latha. "Removal of Heavy Metals from Drinking Water by Adsorption onto Limestone with a Focus on Copper and Aluminum Applications." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1204.

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Elevated levels of arsenic and other heavy metals like copper, aluminum, zinc, and selenium in drinking water are found to have deleterious effects on human health. Hence, finding methods for reducing their levels is critical. Iron-coated limestone is used as an adsorption material for the removal of heavy metals from drinking water. Removal of heavy metals by native or uncoated limestone was also observed and used for comparison to and evaluation of the improvement in removal efficiency from the ironcoated material. The removal efficiency with limestone was studied for different concentrations of heavy metals. Kinetic studies were done to determine the decrease in heavy metal concentration as a function of time using limestone. Inductively coupled plasma spectroscopy was used for metal analysis. The effective removal rate of copper and aluminum was found to be four hours and one hour, respectively. This method of removal by using limestone is cost effective, eco-friendly, and hence, of great potential importance for heavy metal removal. Iron-coated limestone is used as an adsorption material for the removal of heavy metals from drinking water. This project will investigate techniques to improve removal efficiency of heavy metals using limestone-based material through adsorption. This research will assist in the development of a granular adsorbent product that will remove metals and that can be manufactured and sold for use at the drinking water source, at point-of-use, or at point-of-entry. Limestone is readily available and its use for metals removal is relatively inexpensive. The technology can be adapted to small, rural water supply systems. Benefits of this research will include a low-cost treatment technology for source reduction that will reduce select metals to below drinking water standards.

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Babalola, Bolanle. "Investigating adsorption characteristics of Delonix regia for heavy metals removal in wastewater and its potential for remediating contaminated soils." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/124050/.

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There is need to explore all possible agro-based inexpensive adsorbents and study their feasibility for heavy metal removal with the aim of finding which is a better alternative to activated carbon. The focus of the present study is on investigating the adsorption characteristics of Delonix regia for the sorption of Pb, Ni, Cu, Cd and Co from polluted water and stabilization of contaminated soils. The focus also included assessment of available metal concentrations, pool size and kinetic resupply using Diffusive Gradient in Thin film (DGT) technique and DGT- Induced Fluxes in Sediments (DIFS) model. Batch adsorption experiments were carried out using the adsorbent prepared from the pods and leaves of Delonix regia in order to determine the suitable operating parameters for the adsorption of the target heavy metals from synthetic metal solutions. Results showed significant uptake occurred at pH 2 which makes the adsorbent suitable for use on low pH heavy metal bearing effluents. An interaction time of 30 minutes was sufficient to achieve maximum uptake. The kinetics of adsorption best fitted to the pseudo second order kinetic model while Langmuir and Freundlich isotherms were used to interpret data obtained from initial concentration study. The experimental adsorption capacity of the pods is 31.2mgPb/g; 5.9mgNi/g; 9.1mgCu/g; 6.5mgCd/g and 5.8mgCo/g while the leaves powder has 10.3mgPb/g; 10.3mgNi/g; 9.2mgCu/g; 8.4mgCd/g and 10.3mgCo/g. The investigation on the sorption ability of Delonix regia continued by using the pods on tropical soil samples to study the effect of aging; pollutants concentration difference; soil pH and soil organic matter on the removal efficiency of Delonix regia pods and biochar for Pb, Cu and Cd during the 42 days aging time. Results showed that removal efficiency was dependent on aging and soil pH for both materials and all metals studied except for Cd where soil pH had no effect. Delonix regia could be used to remove these target metals from organic matter rich agricultural soil while the biochar with higher removal efficiency in most soil samples is better suitable for acidic and poor organic matter soils. Further investigation for availability and resupply kinetic assessment before and after remediation was done using the DGT technique and DIFS model. The use of Delonix.regia and biochar resulted in a reduction in Css and CDGT for all metals in the order of Biochar-treated soils < D. regia treated soils< control samples; an evidence of the good remediation that was achieved by each treatment. The labile pool size of metals, Kd, (Pb, Cu and Cd) that can be resupplied to soil solution from the soil solid phase follows the order of Bio-treated soils > Delonix.regia treated soils > control soil samples. The depletion time (Tc) and the desorption rate constant, k-1, values followed the order: control samples > Delonix.regia treated soil > biochar treated soils. The Kd, labile pool size is increasing with aging time. In control samples, the Tc decreased with aging; while in treated soils, Tc increased with aging and D.regia have the higher value. In the soils to which organic matter, OM, were added, Tc values were the same for each metal throughout the aging period. The values obtained were the same for individual soil with and without treatment but vary from metal to metal. In the OM soils, treatment types and aging have no effect on metal resupply. The resupply of Pb is the fastest, then Cd and the slowest was Cu. The R values in the control soils were reducing with aging but in the treated soils, it was increasing with the resupply slower in D.regia treated soils than biochar treated soils. This work has demonstrated that D.regia has the potential for simple, cheap and effective/efficient remediation of metal polluted waters and soils.

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39

Fike, Wonae Bong. "Sorption of Cadmium, Copper, Lead, and Zinc as influenced by pH, ionic strength and selected soil components." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29430.

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Metals sorption in soils is influenced by several factors, including pH, ionic strength, the presence of ionic composition or organic ligands, total amount of metals, and adsorbent loading. These conditions should be considered when evaluating metal sorption capacity of soil material or when applying laboratory results to field conditions. Metal sorption experiments were conducted on Bertie sandy and Starr-Dyke clay loam soils from long-term field studies in which soils received annual applications of copper-rich pig manure for 16 years. Adsorption of Cd, Cu, Pb, and Zn as affected by different background electrolytes at various concentrations was investigated. Electrolytes were Na+, Ca2+, or Al3+ in perchlorate solution, and their concentrations ranged from 0.001 to 0.5 molc L-1. Increasing ionic strength decreased metal adsorption capacity. Electrolyte cation composition had a greater effect on adsorption than did electrolyte concentration. The order of sensitivity to cation composition of the electrolyte was Zn > Cd > Cu > Pb, and this effect was greater in Bertie sandy loam than Starr-Dyke clay loam soils. Little difference in Cu and Pb adsorption was observed between Na+ and Ca2+ in background solution. Most added Cu was adsorbed at low concentrations regardless of pH, but at high concentrations Cu sorption was strongly related to solution pH. Increases in pH resulted in greater Cu sorption due to pH-dependent negative charges and precipitation. The USEPA recommends that soil systems receiving high metal loading rates be maintained at pH 6.5 or above because of the increased metal adsorption. However, pig manure applications to the Bertie soil resulted in greater Cu in soil solution than in control (no manure) soil at pH > 6.5 due to soluble organic matter. Using the Langmuir equation to determine adsorption maxima for soil systems does not always give adequate estimates of adsorption and values from the equations are highly dependent upon soil environmental parameters. Given the limitations in prediction of adsorption maxima, and given that the amount of nonsorbed metal is as important as the adsorbed amount, the isolines of metal remaining in soil solution were provided with a given set of soil environmental factors. Ph. D.

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Benavente, Martha. "Adsorption of Metallic Ions onto Chitosan : Equilibrium and Kinetic Studies." Licentiate thesis, Stockholm : Kemiteknik, Chemical and Engineering and Technology, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4746.

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Bunhu, Tavengwa. "Preparation and evaluation of Lignocellulose-Montmorillonite nanocomposites for the adsorption of some heavy metals and organic dyes from aqueous solution." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/535.

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The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.

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Efome, Johnson Effoe. "Development and Characterization of Novel Nanofibrous Metal–Organic Framework Adsorption Membranes for Water Treatment." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38245.

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Membrane technology has become a predominant process in providing one of the key components of life (water), either through water and wastewater treatment for water quality purposes or desalination as seen in Ultra-filtration, Nano-filtration, Reverse osmosis, Membrane distillation, Pervaporation, among others. With the ever-increasing demand for portable water due to population increase, constant research has focused on the improvements of the performances of the different water treatment systems including enhancing the performance of the membrane. Among all the different membrane performance enhancement techniques exploited, incorporation of filler has gained much grounds in the last decades. Traditional fillers like silica gel, activated carbon, metal oxides and zeolites are now being challenged by the recent class of mesoporous materials known as Metal Organic Frameworks (MOFs), which are built of metal ions or metal ion clusters linked together by organic ligands giving these materials tunable pore geometries and pore volume, greatly improved surface area with extraordinary adsorptive properties. The membrane incorporating MOFs demonstrate enhance performances more than the other fillers due to the good coordination of the organic moiety and polymers. The overall objective of this project is to develop and study a membrane incorporated MOFs nanofiber system vis-à-vis their applications in heavy metal contaminated water treatment, stability in aqueous media and the advantages and drawbacks of these composite membranes with regards to the quality of the water produced. The developed materials were characterized by SEM, FTIR, TEM, XPS, DSC, and TGA. The heavy metals earmarked for this study include; Lead, Mercury, Cadmium, and Zinc and were studied using flame atomic absorption spectrometry (FAAS). Upon successful fabrication of the nanofiber membranes, detailed adsorption studies were conducted (pristine MOF, pristine nanofibers, enmeshed MOFs) to establish adsorption kinetics and isotherm, which were used further to select the best performing membranes for filtration application. Two different MOFs were used, MOF808; made of Zirconium and Benzene Tricarboxylate) and MOF F300; made of Iron and Benzene Tricarboxylate) The adsorption capacities of the MOFs for the different heavy metal analyzed were; MOF 808 (Pb-170.74 mg g-1, Zn-287 mg g-1, Cd-225.05 mg g-1, Hg-276.96 mg g-1) and MOF F300 (Pb-148.13 mg g-1, Hg-229.66 mg g-1), while the membrane adsorption capacities were; PA808 (MOF 808 embedded within polyacrylonitrile (PA) nanofibers, (Pb-23.98 mg g-1, Hg-50.88 mg g-1), PA300, MOF F300 embedded within polyacrylonitrile nanofibers, (Pb-30.19 mg g-1, Hg-53.09 mg g-1). Upon activation of MOF 808 by water (hydractivation), the removal efficiency of MOF 808 was improved by 10% while the MOF membrane efficiency was increased by 30%. Filtration experiments could produce 577.5 L of treated water with a single layer of PAN/ MOF808 membrane at 0.1 bar using a 50 ppb Pb ion feed solution.

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43

Almeida, Neto Ambrósio Florêncio de 1979. "Caracterização e avaliação de argilas como adsorventes na remoção e eluição de íons cobre e mercúrio em diferentes sistemas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266897.

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Orientador: Meuris Gurgel Carlos da Silva Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Made available in DSpace on 2018-08-17T12:46:26Z (GMT). No. of bitstreams: 1 AlmeidaNeto_AmbrosioFlorenciode_D.pdf: 8740127 bytes, checksum: 97f85966180df66452b1975b682bc9e1 (MD5) Previous issue date: 2011 Resumo: A remoção de metais pesados por argilas, baseada na tecnologia de purificação da água, tem sido investigada como uma alternativa aos métodos tradicionais. Argilas do tipo esmectítico são as de maior utilização industrial, sendo considerada a mais interessante das argilas industriais. Todavia em diversos casos faz-se necessário submetê-las a tratamentos físicos e químicos para aprimorar suas potencialidades. Assim, estudou-se, no presente trabalho a remoção dos íons cobre e mercúrio, em laboratório a partir de soluções sintéticas, a adsorção sobre as argilas calcinadas dos tipos Bofe e Verde-lodo. Tais íons são recorrentemente produzidos e acumulados no meio ambiente e sua recuperação, para posterior reuso, tem cada vez mais importância a medida que não apenas o tratamento da água residuária e necessário, mas o aproveitamento dos subprodutos e incentivado, por acarretar benefícios econômicos e ambientais. Dessa forma, estudos a respeito de técnicas de remoção dos íons metálicos, assim como do equilíbrio e da cinética do processo, são necessários para a viabilização do procedimento de recuperação. As técnicas de remoção abordadas nesse trabalho foram a de banho finito e de leito fixo e seus objetivos foram avaliar os mecanismos e taxas de remoção dos íons de cobre e mercúrio, a partir do levantamento das curvas de equilíbrio e cinéticas de cada íon. Os ensaios monocomponentes, em banho e leito, mostraram que o cobre tem afinidade pelos sítios das argilas, mas o mercúrio não. As maiores capacidades de adsorção do cobre foram de 0,14 e de 0,22 mmol/g, em leito, sobre as argilas Bofe e Verde-lodo calcinadas, respectivamente. Quanto ao resultado de adsorção binária observa-se, que a remoção do mercúrio foi um pouco melhor, comparando com a remoção quando este metal encontrava-se em solução monocomponente. Provavelmente, devido ao efeito sinérgico, o cobre adsorvido favoreceu a remoção do mercúrio. A remoção do mercúrio na mistura binária foi reduzida quando o cobre apresentou porcentagens de remoção inferiores a 95%. Para regeneração dos leitos de argila calcinada foram utilizados diferentes eluentes. Estes ensaios foram realizados através de diversos ciclos de remoção/eluição utilizando colunas de leito fixo. Os resultados indicaram que a regeneração do leito com NaCl/HCl ou água salina a pH 3 e bastante eficiente, sendo a eluição de ate 100% e um crescimento na remoção foi observado após a exposição do leito ao eluente Abstract: The water purification based on technology the metal removal by clays has been investigated as an alternative to traditional methods. Smectite clays have the major industrial use besides being considered the most interesting clays. However in many cases is necessary submitting them physical and chemical treatments with the aim of enhancing their capabilities. Thus, we studied in the present project the removal of copper and mercury of synthetic solutions in the laboratory moreover the adsorption on the calcined clays types Bofe and Verde-lodo. These ions are commonly produced and accumulated in the environment and their recovery for their reuse has become increasingly important not only for the treatment of wastewater in addition the utilization of the byproducts achieve economic and environmental benefits. Studies on techniques for removal of metal ions, as well as equilibrium and kinetics of the process are necessary for the viability of the recovery procedure. The removal techniques discussed in this study were realized in the finite bath and fixed-bed with the purpose to evaluate the mechanisms and removal ions rates of copper and mercury, the time of equilibrium and kinetic curves of each ion. Tests single component, in the bath and fixed-bed have showed that the copper has affinity with the clays, in contrast with the results obtained for the mercury. The highest adsorption capacities of copper were 0.14 and 0.22 mmol/g, in fixed-bed, on the Bofe and Verde-lodo calcined clays, respectively. The tests carried out in binary adsorption evidence that the removal of mercury was slightly better in comparison with removing this metal in a monolithic solution. Probably due to the synergistic effect, copper adsorbed favored the removal of mercury. Mercury recovery on the binary mixture decrease when copper ions presented removal percents less than 95%. Deferent's types of eluents were utilized for calcined clays bed regeneration. These tests were performed through several removal/elution cycles using fixed bed columns. These results indicated that the regeneration of the bed with NaCl/HCl or saline water at pH 3 is very efficient, the elution was of 100% and an increase in removal was observed after exposure of the bed to the eluent Doutorado Engenharia de Processos Doutor em Engenharia Química

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BAKRY, AYYOB MOHAMMED A. "Applications of Chemically Modified Nitrogen Doped Carbon, Zirconium Phosphate, Metal Organic Frameworks, and Functionalized Graphene Oxide Nanostructured Adsorbents in Water Treatment." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6105.

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Water contaminations by many pollutants, especially heavy metals such as Pb(II), Hg(II), Cu(II), Cd(II), and Cr(VI) pose many public health and environmental concerns as reported in the list of hazardous substances compiled by the US Environmental Protection Agency due to their high toxicity, refractory degradation, and ease of entering food chain. Adsorption by chelating resins is proven to be the most effective method for the extraction of metal ions from polluted and wastewater. However, traditional absorbents such as activated carbon, activated alumina, clay, zeolite, etc., show limited adsorption abilities for these heavy metal ions. The major goal of this thesis is to develop eﬃcient and cost-eﬀective adsorbents for the extraction of heavy metals from wastewater. This dissertation will focus on the development of four chemically modified high surface area adsorbents with accessible chelating sites for capturing and retaining toxic metal ions from polluted water. The first adsorbent, Nitrogen Doped Carboxylated Activated Carbon (ND-CAC), is prepared by a polymerization reaction between melamine and formaldehyde to form the melamine formaldehyde resin (MF-R) followed by carbonization at 800 oC under nitrogen atmosphere to form nitrogen doped carbon (ND-C), and finally oxidation to form the ND-CAC adsorbent. The ND-CAC adsorbent shows high adsorption capacities of 750.5, 250.5, 98.2 mg/g for the extraction of Pb(II), Hg(II), and Cr(VI), respectively from aqueous solutions with a high selectivity to Pb(II). The second adsorbent, Melamine Zirconium Phosphate (M-ZrP) is prepared by a precipitation reaction between Melamine Phosphate (MP) and ZrCl4 in an aqueous solution. The M-ZrP adsorbent is used for the removal of Pb(II), Hg(II), and Cd(II) with maximum adsorption capacities of 680.4, 119.0, and 60.0 mg/g, respectively with a high selectivity to Pb(II). The third adsorbent is chemically functionalized metal organic framework (UIO-66-IT) was prepared by post-synthetic modification using the chelating ligand 2-Imino-4-Thioburit. The adsorbent was used to extract Hg(II) and (HPO4)- ions from aqueous solutions and the results revealed exceptionally high adsorption capacities toward mercury and phosphate ions of 700 and 160 mg/g, placing it among the top functionalized MOF known for the high capacity of Hg(II) removal from aqueous solutions. The fourth adsorbent, Melamine Thiourea Partially Reduced Graphene Oxide (MT-PRGO) prepared by the amidation reaction between chemically modified graphene oxide and melamine thiourea, is used for the effective extraction of Hg(II), Co(II) and Cu(II) from polluted water. The MT-PRGO adsorbent shows exceptional selectivity for the extraction of Hg(II) with a capacity of 651 mg/g, placing it among the top of carbon-based materials known for the high capacity of Hg(II) removal from aqueous solutions. Desorption studies demonstrate that the new adsorbents ND-CAC, M-ZrP, UIO-66-IT, and MT-PRGO are easily regenerated with the desorption of the heavy metal ions Hg(II), Pb(II), Cd(II), and Cr(VI) reaching 99 % - 100 % recovery from their maximum sorption capacities using different eluents. Moreover, all prepared adsorbents showed tremendous abilities to clean contaminated water from toxic heavy metals at trace concentrations. That prove the ability of using them at water contamination level when the concentration of heavy metals is very low. The new adsorbents ND-CAC, M-ZrP, UIO-66-IT, and MT-PRGO are proposed as top performing remediation adsorbents for the extraction of the heavy metals Pb(II), Hg(II), Cd(II), Cr(VI), and (HPO4)- from waste and polluted water.

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Benamer, Mustafa Alarabi. "Chemical speciation and spatial distribution of heavy metals and their adsorption onto sediments of the Berg River, Western Cape, South Africa." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13167.

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Includes bibliographical references. The Berg River, Western Cape, South Africa, is an example of a catchment region where human pressures and conservation of natural resources collide. The river receives effluents from two large settlements and several smaller adjacent villages, including that of industrial and extensive agricultural activity. The estuary is one of the largest in South Africa and rated as the third most important conservation zone in the country. In this study, the chemical speciation of heavy metals in the river sediment was determined in order to evaluate the extent of pollution. Chemical speciation using sequential chemical extraction of sediment samples was used to measure the mobility and bioavailability of cadmium (Cd), lead (Pb), arsenic (As), chromium (Cr), nickel (Ni), cobalt (Co), iron (Fe), copper (Cu), zinc (Zn) and manganese (Mn). The metals Cd and Zn were found to be the most mobile and bioavailable. The study also examined the vertical distribution of heavy metals in estuarine sediment cores to evaluate the extent of heavy metal contamination with time and the degree to which heavy metals are influenced by other sedimentological parameters such as grain size, sediment composition and organic matter. Three sediment cores, ranging from 160 to 240 em long, were collected using a mechanical vibrating corer. The vertical distribution of metals in the cores showed that the metal concentration was higher at the top and middle of the cores. Based on the enrichment factor (EF) and anthropogenic factor (AF) values, it is suggested that the sediments of the estuary are not polluted with Co, Mn, Cu, Ni, Zn and Fe but moderately to highly polluted with Pb, As, Cd and Cr. The data reported provide a useful baseline for establishing heavy metal concentrations in the estuary and will be an important consideration in future sediment quality studies. The spatial distribution of the metals was also studied to understand how location is linked to metal concentration. The average concentration of metals in the core sediment increased with increasing distance from the mouth of the river. The adsorption behaviour of the estuary sediment with micro-pollutants has a significant influence on the environmental quality of estuary waters. For this reason, the absorption of Pb, Cr, Cu, Ni, and Zn onto sediment was study. It was found that the sediments of the Berg River estuary have a low potential for absorption of Ni and Zn making these metals more mobile and bioavailable.

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Salih, Ali Mohammed. "The purification of industrial wastewater to remove heavy metals and investigation into the use of zeolite as a remediation tool." Thesis, University of Wolverhampton, 2018. http://hdl.handle.net/2436/621859.

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Zeolites are well-known aluminosilicate minerals that have been widely used as adsorbents in separation, purification processes and environmental pollution control. Zeolites are used in various industrial applications due to their high cation-exchange ability, molecular sieve and cataltic properties. In order to reduce the costs of acquisition and minimise the disposal of adsorbents, both modified natural zeolite and synthetic zeolite (derived from kaolinite) were used for the purification of wastewater. The characteristic properties and applications of adsorbents are also discussed including the advantages and disadvantages of each technique. The present work involves the study of the removal of Cu2+, Fe3+, Pb2+ and Zn2+ from synthetic metal solutions using natural zeolite. Laboratory experiments were used to investigate the efficiency of adsorbents in the uptake of heavy metals from industrial wastewater. These include equilibrium tests, kinetic studies and regeneration studies. The physical and chemical characterization of the zeolites was carried out using different analytical techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X - Ray Diffraction (XRD), X - Ray Fluorescence (XRF), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR) Spectroscopy and Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The kinetic study indicated the suitability of the natural zeolite for the removal of Cu2+, Fe3+, Pb2+ and Zn2+ ions from synthetic wastewater. Batch experiments were used to identify the effect of parameters that affect the rate of adsorption such as the effect of adsorbent mass, effect of adsorbent particle size, effect of initial solution pH, effect of initial solution concentration, effect of agitation speed and effect of pre-treatment of adsorbent and evaluated their impact on the efficiency of the zeolite in the removal of heavy metals from industrial wastewater. The kinetic studies showed that the capacity of the adsorbents for the removal of heavy metals increased with a greater mass of absorbent, increased initial solution pH, increased agitation speed, higher solution concentration as well as the application of a pre-treatment. The results from the equilibrium studies positively demonstrated that natural zeolite can be used as an excellent adsorbent for removing heavy metals from multi-component solutions. The equilibrium experiments indicated that the capacities of natural zeolite for the uptake of heavy metals increased when the initial solution pH increased. The results indicated that the maximum removal capacities Q were 22.83, 14.92, 14.49 and 17.54 mg/g natural zeolite for copper, iron, zinc, and lead respectively. Both the Langmuir and Freundlich isotherm models were used to characterize the experimental data and to assess the adsorption behaviour of natural zeolite for copper, iron, lead and zinc. The experimental data were slightly better suited to the Langmuir isotherm than the Freundlinch isotherm. The value of the correlation coefficients r2 ranged from 0.93 to 0.99 for the Langmuir isotherm and from 0.90 to 0.99 for the Freundlich isotherm. The present work also involved the study of synthetic zeolite A, which was derived from natural kaolinite. The conversion of the raw materials into zeolitic materials was carried out in two ways: first, conventional hydrothermal synthesis and second, alkaline fusion prior to hydrothermal synthesis. The results from both routes show that zeolite A was synthesised successfully. Finally, the experiments show that both natural and synthetic zeolites can be available in commercial quantities. Synthetic zeolites are more attractive for some specific applications, while the cheapness of natural zeolite may favour its use.

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47

Lima, Lívia Katia dos Santos 1985. "Estudo da sorção de íons de CR(III) utilizando a macrófita aquática Lemna minor." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266905.

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Orientadores: Meuris Gurgel Carlos da Silva, Sirlei Jaiana Kleinübing Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Made available in DSpace on 2018-08-18T23:27:40Z (GMT). No. of bitstreams: 1 Lima_LiviaKatiadosSantos_M.pdf: 1864490 bytes, checksum: 67f5d9bfb35ec8ec36e1d0cd3334477e (MD5) Previous issue date: 2011 Resumo: Nas últimas décadas tem-se observado sérios impactos ambientais tendo o desenvolvimento tecnológico e industrial como fonte geradora no que diz respeito ao descarte sem controle de substâncias poluentes no meio ambiente, em particular, a poluição dos recursos hídricos. Diversos problemas relacionados a crescentes despejos de metais pesados em corpos d'água pela indústria são motivo de grande preocupação, o que vem fomentando pesquisas voltadas para o desenvolvimento de técnicas de remoção destes poluentes dos efluentes industriais. Neste contexto a adsorção vem sendo avaliada como um processo viável por possuir uma vasta variedade de materiais que podem ser utilizados como adsorventes. Dentre estes materiais, as macrófitas aquáticas se destacam por possuirem características adequadas como capacidade de se desenvolverem em diferentes faixas de temperatura e pH variados, fácil cultivo e grande afinidade com íons metálicos. Neste trabalho a macrófita aquática Lemna minor foi utilizada na remoção de íons de Cr3+ de soluções aquosas utilizando um sistema em batelada. A escolha do Cr3+ foi feita a partir da observação de que grandes quantidades deste metal são utilizadas em processos industriais, principalmente naqueles relacionados ao processamento de couro. A avaliação da capacidade de bioadsorção do Cr3+ pela macrófita aquática Lemna minor foi realizada em ensaios de equilíbrio e cinéticos. Análises de espectroscopia (FTIR) mostraram a presença de grupos carboxílicos, carboxilatos e C-Cl na superfície da biomassa que participam diretamente do processo de adsorção. O modelo de Langmuir foi ajustado aos dados de equilíbrio e a capacidade máxima de adsorção foi de 11,66 mg.g-1 para uma temperatura ótima de 30 ºC. Os dados cinéticos obtidos foram analisados pelo ajuste dos modelos de pseudo-primeira, pseudo-segunda ordem e difusão intrapartícula. Porém, o modelo de pseudo-segunda ordem se ajustou mais adequadamente aos dados experimentais. Ensaios de dessorção foram também realizados com intuito de verificar a possibilidade de regeneração do adsorvente utilizando diferentes eluentes Abstract: In the last decades serious environmental impacts can be observed as a result of the technological and industrial development which is the mainly generating source when related to uncontrolled disposal of pollutants in the environment, in particular, water resources pollution. Several problems related to increasing discharges of heavy metals in water bodies by the industry causes concern. It has promote research for the development of techniques for removing these pollutants from industrial effluents. In this context, adsorption has been evaluated as a viable process for having a wide variety of materials that can be used as adsorbents. Among these materials, the aquatics macrophyte stand to possess suitable characteristics as ability to grow in different ranges of temperature and pH varied, easy cultivation and high affinity for metal ions. In this work the Duckweed Lemna minor was used in the removal of Cr3+ from aqueous solutions using a batch system. Cr3+ metal was chosen due the observation that large amounts of this metal is used in industrial processes, particularly those related to leather processing. Assessing the ability of biosorption of Cr3+ by Duckweed Lemna minor was performed in equilibrium tests and kinetics. Spectroscopy Analysis (FTIR) showed the presence of carboxylic, carboxylate and C-Cl groups on the biomass surface. These groups directly participate in the adsorption process. The Langmuir model was fitted to the equilibrium data and maximum adsorption capacity was 11.66 mg.g-1 in an optimum temperature of 30 °C. The kinetic data were analyzed by fitting the pseudo-first, pseudo-second order and intraparticle diffusion models. However, the model of pseudo-second order fit better to experimental data. Desorption tests were also conducted in order to verify the possibility of regeneration of the adsorbent using different eluents Mestrado Engenharia de Processos Mestre em Engenharia Química

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48

Sanyahumbi, Douglas. "Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1003960.

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The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.

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49

Mbhele, Njabulo. "Adsorption of heavy metals on marine algae." Thesis, 2005. http://hdl.handle.net/10413/2825.

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Biosorption is a property of certain type of inactive, microbial biomass to bind and concentrate heavy metals from even very dilute aqueous solutions. Biomass exhibits this property, acting just as a chemical substance, as an ion exchanger of biological origin. It is particularly the cell wall structure of certain algae that is found responsible for this phenomenon. In these experiments, the rate and extent for removal of copper is subjected to parameters such as pH, initial metal concentration, biosorbent size, contact time, temperature and the ability of the biomass to be regenerated in sorption-desorption experiments. The metal adsorption was found to be rapid within 25 minutes. The maximum copper uptake of 30 mg of copper / g of biomass has been observed, in the following conditions: 100 mg / L, 0.1 g of biomass, pH 4 and at temperature of 25°C. From this study, it was found that copper uptake is increasing with increase in pH, with optimum being pH 4. Copper uptake increases substantially from 0 to 25 minutes. Metal biosorption behaviour of raw seaweed Sargassum in six consecutive sorptiondesorption cycles were also investigated in a packed-bed column, during a continuous removal of copper from a 35 mg/l aqueous solution at pH 4. The sorption and desorption was carried out for an average of 85 and 15 hours, respectively, representing more than 40 days of continuous use of the biosorbent. The weight loss ofbiomass after this time was 13.5%. The column service time decreased from 25 hrs in the first cycle to 10 hrs for the last cycle. Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

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50

Hsien, Chi-Ying, and 謝季穎. "Isotherm Adsorption of Heavy Metals by Using MSW." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/86512276855313881912.

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碩士 朝陽科技大學 環境工程與管理系碩士班 96 Municipal solid waste (MSW) is treated mainly by MSW incinerator (MSWI) and partly by landfill and other methods. After incineration, MSWI ashes are generated by up to 15% of original MSW volume while gaining the steam and electricity. Co-disposal or co-digestion of MSW with MSWI ashes is one of MSWI ash utilization. However, release of different metals and their levels may affect the MSW biodegradation. Particularly, the heavy metals released from MSWI ashes may inhibit the MSW digestion. In order to understand the adsorption of heavy metals on MSW, isotherm adsorption was conducted for the evaluation of heavy metals solubility and adsorption in MSW. The result may be used as reference to the co-disposal or co-digestion of MSW and MSWI ashes in landfill or in anaerobic digesters. Thus, this study aims to investigate the isotherm adsorption of Cd, Cr, Cu, Pb, Ni and Zn by using MSW. The environmental factors include initial concentrations, adsorption time, pH and temperature. Initial concentrations of heavy metals contain 100, 200, 400, 600 and 800 mg/L respectively. Adsorption time is 0, 5, 10, 30, 60 and 120 min, pH is 1, 3, 5, 7, 9, and 11, temperature is 10, 20, 30, 40, 50 and 60 ℃ respectively. These environmental factors are used to observe the heavy metals capacity by MSW. The analyzed data are examined by Langmuir and Freundlich isotherm model, kinetics model and thermodynamic model. Results show that analyzed data are fitted better by Langmuir model than Freundlich model with a higher R2 found in Langmuir model. Among six heavy metals, Pb is found to be adsorbed highest on MSW. At the conditions of initial concentration 800 mg/L, adsorption time 120 min, pH 7 and temperature 20 ℃, the adsorption order is Pb (13.17) > Cr (9.94) > Cd (6.59) > Zn (5.76) > Cu (2.95) > Ni (2.39) mg/g respectively. Results of kinetic model study also show that adsorption procedure is fitted better by second order kinetics than first order kinetics and both of their R squares are higher than 0.99. Thermodynamic study results show that heavy adsorption is exothermic. From these results, it shows that heavy metals adsorption and the solubility of metal ions in MSW　that may affect MSW anaerobic digestion process might be used as a reference for the co-disposal or co-digestion of MSW and MSWI ashes in landfill or anaerobic bioreactors.

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