Academic literature on the topic 'Freundlich Isotherm'
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Journal articles on the topic "Freundlich Isotherm"
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Lan, Hui Xia, Xiao Feng Liu, Rui Chen, and Heng Zhang. "The Adsorption of Pentachlorophenol (PCP) on Aerobic Granules." Advanced Materials Research 599 (November 2012): 354–57. http://dx.doi.org/10.4028/www.scientific.net/amr.599.354.
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the adsorption of PCP using aerobic granules was studied. The static adsorption experiments were carried out and the Freundlich and Langmuir adsorption isotherms were applied to describe the biosorption processes and the isotherm constants were evaluated. The Freundlich and Langmuir isothermy adsorption equations obtained from the static experients were q=2.04ce0.82 and q=3.47ce /(1+0.56 ce), respectively. Both the adsorption isotherms described the static adsorption behavior of PCP well. Then the Freundlich adsorption isotherm was used to estimate the adsorption of PCP by aerobic granules in the dynamic state. The results showed that the adsorption mainly occurred in the initial periods during the operation of the reactor.
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Gong, Zheng Jun, Wenbo Zhou, and Zhong Ping Qiu. "The Study of Copper (II) Removal from Aqueous Solutions by Adsorption Using Corn Stalk Material." Advanced Materials Research 610-613 (December 2012): 1950–53. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.1950.
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In this study, removal of copper(Ⅱ) from aqueous solutions was examined using corn stalk. In the batch mode adsorption studies, the effects of initial pH and contact time on the copper(Ⅱ) adsorption by the corn stalk have been studied. The results show that: the pH 6.0 and contact time 8 hrs is optimum conditions of this absorption process when the dosage of corn stalk is 0.1g. In the isotherm studies, the Langmuir and Freundlich isotherm models were applied. The R2 of the Langmuir and Freundlich isotherm are 0.981 and 0.944 respectively. The Langmuir adsorption capacity Qmax is 54.05 mg/g. The goodness of fitness was obtained with the Langmuir and Freundlich adsorption isotherms.
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Hastuti, Budi, Mudasir Mudasir, Dwi Siswanta, and Triyono Triyono. "Preparation and Pb(II) Adsorption Properties of Crosslinked Pectin-Carboxymethyl Chitosan Film." Indonesian Journal of Chemistry 15, no. 3 (November 12, 2015): 248–55. http://dx.doi.org/10.22146/ijc.21192.
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A modified pectin has been synthesized by reacting/combining -OH group among pectin and chitosan with BADGE (Bisphenol A diglycidyl ether) crosslinker agent. The structure and morphology of the new material were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray Diffraction (XRD) analysis. Thermogravimetric studies showed an improvement in thermal characteristic. Adsorption experiments were performed in batch processes; sorption isotherms and kinetics were also studied. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Pb(II) ion onto adsorbent pectin-carboxymethyl chitosan-BADGE (pec-CMC-BADGE). The dynamic study showed that the sorption process followed the second-order kinetic equation. Result indicated also that Pb(II) ion uptake could be well described by the Langmuir and Freundlich adsorption model of pec-CMC-BADGE and CMC with DG° of 25.3 and 23.1 kJ mol-1,respectively, while that of pectin followed Freundlich isotherm with DG° of 16.6 kJ mol-1.
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Olafadehan, Olaosebikan A., and Alfred A. Susu. "Numerical Solution of Binary Liquid-Phase Adsorption onto Porocel Clay Using Linear, Freundlich and Langmuir Isotherms." Adsorption Science & Technology 23, no. 3 (April 2005): 195–213. http://dx.doi.org/10.1260/0263617054353627.
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A generalized mathematical model is presented to describe the process of multi-component adsorption onto porous media in fixed beds. The model was applied to the binary adsorption, without reaction, of aromatics and sulphur compounds onto a fixed bed of Porocel clay for kerosene deodorization using linear, Freundlich and Langmuir isotherms independently. A computational scheme for the solution of the model equations is presented. The scheme is based on orthogonal collocation for spatial discretization of the resulting set of coupled hyperbolic and parabolic partial differential equations for the macro-and micro-system, respectively. Michelsen's modified third-order semi-implicit Runge-Kutta method combined with step-size adjustment strategy was used to integrate the resulting 4N ordinary differential equations. Excellent agreement between the simulated results and pilot plant data was obtained for the breakthrough profiles for the non-linear adsorption isotherms of Freundlich and Langmuir. No agreement was obtained for the linear isotherm. Also, using the Freundlich and Langmuir isotherms, the exit concentration of the less preferentially adsorbed component (aromatics) exceeded its inlet concentration to the adsorption column for a certain period. This is indicative of the behaviour of competitive multi-component adsorption: relative to aromatics, sulphur compounds are selectively adsorbed onto Porocel clay. The relationship between solid- and liquid-phase concentration profiles for the Freundlich isotherm revealed the formation of multiple adsorption layers upon the primary mono-molecular layer. Again, for the Freundlich isotherm, the structure of the profiles exhibited a highly pronounced maximum for sulphur. An experimental breakthrough time of 8 h was also predicted for both aromatics and sulphur compounds using the non-linear Freundlich and Langmuir isotherms.
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Tewari, Hemlata, and Vivekanand. "Removal of heavy metals from industrial effluent using Pinus roxburghii leaves as biosorbent: equilibrium modelling." Water Science and Technology 67, no. 9 (May 1, 2013): 1894–900. http://dx.doi.org/10.2166/wst.2013.034.
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In the present study, biosorption capability of pine (Pinus roxburghii) leaves for the removal Cr6+, Cu2+, Fe2+ and Zn2+ ions, present in brass and electroplating industry effluent, were investigated with respect to different adsorbent doses, contact time and pH. Heavy metals concentrations were estimated by atomic absorption spectrophotometry. Initial concentration of Cr6+, Cu2+, Fe2+ and Zn2+ ions in the effluent were found to be 2.741, 4.551, 8.820 and 5.529 mg/L respectively. Biosorption studies revealed that Cr6+, Cu2+, Fe2+ and Zn2+ showed maximum removal of 99.85, 94.54, 97.10 and 89% at pH 4, 4, 4 and 8, respectively, with 4 g pine leaves when shaken at 150 rpm for 60 min. The applicability of the three equilibrium isotherm models was investigated and the data obtained fitted the three investigated isothermal models in the order: Langmuir > Temkin > Freundlich for all the studied metal ions. The adsorption isotherm coefficients, Qmax, b, Kf, n, at, bt were also calculated. Very high regression correlation coefficients (R2 > 0.9) were found for Cu2+, Fe2+ and Zn2+; Cr6+ (Temkin isotherm) when pH (2–8) was varied; Cr6+, Cu2+,Fe2+ and Zn2+ when contact time (15–60 min) was varied; Cu2+ (Langmuir isotherm) Fe2+ (Freundlich and Temkin isotherms) when adsorbent was varied from 2 to 5 g. Results also revealed that among all the studied ions Cr6+ at varied pH and Fe2+ at different adsorbent doses satisfy the Temkin and Freundlich isotherm models to describe the biosorption equilibrium by pine (Pinus roxburghii) adsorbent.
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Buaphean, Tanaree, Thamonwan Ketwongsa, and Kowit Piyamongkala. "Coagulation of Chitosan Solution in Commercial Detergent as Adsorbent for Sorption Methylene Blue Dye." Solid State Phenomena 266 (October 2017): 122–27. http://dx.doi.org/10.4028/www.scientific.net/ssp.266.122.
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The chitosan resin forming with commercial detergent solution was used as adsorbent for removal of the methylene blue. The effect of the amount of adsorbent was thoroughly investigated through batch adsorption system. The percent adsorption of methylene blue increased in the same direction as the amount of chitosan resin. The experimental result showed that adsorption capacity onto 0.4 g of chitosan resin was 9.1 mg/g. The Langmuir and the Freundlich adsorption isotherms were applied to describe the methylene blue uptake, which could be explained by Freundlich adsorption isotherm onto chitosan resin. Single-state batch adsorption design of methylene blue onto chitosan resin has been studied, using on the Freundlich isotherm equation.
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Hussain, Zainab, Zeyad Fadhil, Sameer Kareem, Salam Mohammed, and Emad Yousif. "Removal of Organic Contaminants from Textile Wastewater by Adsorption on Natural Biosorbent." Materials Science Forum 1002 (July 2020): 489–97. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.489.
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In the present study, removal of safranin dye from water bodies was investigated using natural biosorbent (Thyme leaves (TEL)). The influence of multiple factors such as as contact time (15 – 105 mins), adsorbent dose (25 to 350) mg/l , adsorbate dose (5 to 40)mg\L, and temperature (25 to 55)o C were taken for investigation. The adsorption isotherms were described by utilized Langmuir, Freundlich and Dubnin-Radushkevich models, Freundlich isotherm model found to be best suited with experimental data out of 3 isotherm The adsorption process followed pseudo second order model.
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Dada, A. O., J. O. Ojediran, and Abiodun Paul Olalekan. "Sorption of Pb2+ from Aqueous Solution unto Modified Rice Husk: Isotherms Studies." Advances in Physical Chemistry 2013 (March 18, 2013): 1–6. http://dx.doi.org/10.1155/2013/842425.
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Investigation of the sorption potential of rice husk, an agricultural waste, as an adsorbent was carried out. The rice husk was modified with orthophosphoric acid and was used for adsorption of lead (II) ions (Pb2+) from aqueous solution. Physicochemical properties of the modified rice husk were determined. Equilibrium sorption data were confirmed with Langmuir, Freundlich and Temkin adsorption isotherms. On the basis of adsorption isotherm graphs, R2 values were determined to be 0.995, 0.916, and 0.797 for Langmuir, Temkin, and Freundlich isotherms, respectively, indicating that the data fitted well into the adsorption isotherms, but Langmuir isotherm is a better model. The maximum monolayer coverage from Langmuir studies, Qmax=138.89 mg/g, Langmuir isotherm constant, KL=0.699 L/mg, and the separation factor, RL=1.41×10−2 at 100 mg/L of lead(II) ions indicating that the sorption process, was favourable. The suitability of modified rice husk as an adsorbent for the removal of lead ions from aqueous solution and its potential for pollution control is established.
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Liu, Ming Da, Ge Tian, Liang Jie Zhao, Yao Sheng Wang, Lei Guo, and Yao Jing Wang. "Removal of Pb (II) from Aqueous Solution by Blast-Furnace Slags." Advanced Materials Research 726-731 (August 2013): 2736–41. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.2736.
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Five blast-furnace slags were used as adsorbents to remove Pb (II) from aqueous solution. Kinetic studies showed that the sorption process was best described by pseudo-second-order model. Among Langmuir, Freundlich and Temkin isotherms, the Freundlich isotherm had a better fit with the simulation of the adsorption of Pb (II).
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Ding, Wei, Shuqin Bai, Haorong Mu, and Gaowa Naren. "Investigation of phosphate removal from aqueous solution by both coal gangues." Water Science and Technology 76, no. 4 (April 25, 2017): 785–92. http://dx.doi.org/10.2166/wst.2017.241.
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Equilibrium studies were carried out for the adsorption of phosphate onto newly discharged coal gangue and spontaneous combustion coal gangue, which are industrial solid residues. The experimental data were fitted to the two-parameter equations of Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich and the three-parameter equations of the Redlich-Peterson, Sips and Toth isotherms by non-linear method. All three-parameter isotherm equations have a higher correlation coefficient than the two-parameter isotherm equations. For new discharged coal gangue, the maximum phosphate adsorption capacity is over 2.504 mg/g (as P), and the best two-parameter isotherm is Freundlich, which indicated multilayer adsorption takes place on the surface. For spontaneous combustion coal gangue, the maximum phosphate adsorption capacity is 7.079 mg/g (as P), two times larger than new discharged coal gangue, and the best two-parameter isotherm is Langmuir, suggesting that the adsorption process occurs on a homogenous surface by monolayer adsorption. The three-parameter isotherm model of Redlich-Peterson shows the best fitting in both cases, but parameter g is 0.6138 in new discharged coal gangue (the parameter g is nearly 1, which means that the equilibrium isotherm behaves as the Langmuir, not as the Freundlich isotherm), g approaches to unity in spontaneous combustion coal gangue, suggesting that the two kinds of coal gangues have different adsorption properties.
Dissertations / Theses on the topic "Freundlich Isotherm"
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Duygulu, Yusuf Bahadir. "Decolorization Of Synthetic Dye Solutions By Using Basaltic Tephra And Clinoptilolite." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605241/index.pdf.
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Discharge of colored effluents without decoloration originated from textile industries may cause serious problems in the receiving environments.
In this study, natural materials that are basaltic tephra and clinoptilolite were used to remove various dyestuffs used in the textile industry. Those materials are cheap and available in large quantities in Turkey. The investigation of adsorption of basic, acidic and reactive dyes on these materials is the objective of this study.
During preliminary experiments it was seen that adsorption equilibrium was reached in about 2 days. In adsorption experiments, in order to obtain adsorption isotherms, a fixed amount of adsorbent and 100 mL dye solutions of different concentrations were placed in glass bottles which were shaken at 200 rpm and 25±2oC for 2 days. Then, samples were filtered and the equilibrium concentrations of dyestuffs in the solutions were determined by using spectrophotometer at appropriate wavelength corresponding to the maximum absorbency. After equilibrium concentrations of the solutions were obtained, Langmuir and Freundlich adsorption isotherm constants were calculated for the adsorbents used in this study. The removal efficiencies for cationic basic dyes are higher than those for anionic acidic and reactive dyes with the natural materials. Therefore, modification of surface properties of natural materials with a cationic surfactant was considered to increase the removal efficiencies of those for anionic dyes. After modification of the surface properties, adsorption capacities of adsorbents for anionic dyes were higher than those of natural materials. Finally, the adsorption capacity of activated carbon for the same dyes was determined to compare with that of natural and modified materials. The results showed that the adsorption of dyes on adsorbents used in this study fitted nicely the Langmuir Isotherm Equations.
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Sbizzaro, Mariana. "Adsorção de atrazina em biocarvões obtidos a partir de colmo de bambu." Universidade Estadual do Oeste do Parana, 2016. http://tede.unioeste.br:8080/tede/handle/tede/272.
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Previous issue date: 2016-02-12The agricultural sector has great influence in Brazilian economy. Furthermore, agricultural yield has been associated with pesticides application during crop cycle, which atrazine is applied for example, since it can cause environmental contamination when it does not reach its target. Thus, there are some essential and imperative options that can minimize contamination and negative impacts during agricultural practices. So, present study aimed at evaluating the ability of three biochars in atrazine adsorption. Therefore, three biochars produced from bamboo culm were used, whose species is Phyllostachys aurea, and temperature ranged at 350 ºC, 450 ºC and 550 ºC. The three studied biochars were named as BE350, BE450 and BE550. They were characterized based on their physical and chemical properties by elemental analysis, characterization of functional groups (Infrared Spectroscopy Fourier Transform - FTIR), surfaces morphology evaluation (Scanning Electron Microscopy - SEM) as well as specific surface area (ASEBET) and porosity. A kinetic study was carried out to determine the equilibrium period of adsorption process and the kinetic mechanism that controls such process. Langmuir and Freundlich isotherms were also modeled during this trial. Atrazine determination, after the adsorption test, was carried out by High Performance Liquid Chromatography (HPLC). The obtained analyses showed that the adsorption capacity of biochars decreased in the following order: BE 450> BE 350 > BE 550, and such capacity has been associated with the physical and chemical characteristics of biochars. The three studied biochars are well represented by the kinetic model of pseudo-second order. At last, all biochars have shown high affinity to adsorb atrazine; however, the biochar that was produced at 450 ºC has shown the highest adsorption capacity.
O setor agrícola possui grande destaque na economia brasileira, a produção agrícola está associada ao uso de pesticidas durante o ciclo das culturas, como é o caso da atrazina, que pode causar a contaminação do ambiente, quando não atinge seu alvo. Sendo assim, alternativas que minimizem as contaminações e impactos negativos da prática agrícola são essenciais e urgentes. Desta forma, o presente estudo teve por objetivo avaliar a capacidade de três biocarvões, em adsorver o herbicida atrazina. Para tanto, foram utilizados três biocarvões, produzidos a partir do colmo de bambu, da espécie Phyllostachys aurea à 350ºC, 450ºC e 550ºC, nomeados BE350, BE450 e BE550. Os biocarvões foram caracterizados quanto as propriedades físicas e químicas, por meio de análise elementar, caracterização de grupos funcionais (Espectroscopia de Infravermelho com Transformada de Fourier - FTIR), avaliação da morfologia das superfícies (Microscopia Eletrônica de Varredura - MEV), bem como, área superficial específica (ASEBET) e porosidade. Estudo cinético foi realizado, visando determinar o tempo de equilíbrio do processo de adsorção, bem como, o mecanismo cinético que controla o processo. Também foram modeladas isotermas de Langmuir e Freundlich. A determinação da atrazina, após os ensaios de adsorção, foi realizada por Cromatografia Líquida de Alta Performance (CLAE). As análises realizadas apontaram que a capacidade de adsorção dos biocarvões diminuiu na ordem de BE 450 > BE 350 > BE 550, e tal capacidade está associada às características físicas e químicas dos biocarvões. Os três biocarvões são bem representados pelo modelo cinético de pseudo-segunda ordem. Todos biocarvões exibiram elevada afinidade para a adsorção do herbicida atrazina, contudo, o biocarvão produzido à 450 ºC demonstra maior capacidade de adsorção
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Ndayambaje, Guillaume. "Sorption properties of natural zeolites for the removal of ammonium and chromium ions in aqueous solution." University of the Western Cape, 2011. http://hdl.handle.net/11394/5425.
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>Magister Scientiae - MScThere are huge amount of natural clinoptilolite available in South Africa which can be utilised for wastewater treatment of ammonia and chromium if their characteristics are properly known. However, these deposits have not been well characterised but in this study, the untreated clinoptilolite materials were fully characterised using techniques such as SEM-EDS, HRTEM-SAED, XRD, XRF, FTIR and BET. After acid pretreatment with several extractions, the pretreated samples were again characterised using the above mentioned techniques. These pretreated materials were used for NH₄⁺ and Cr³⁺ adsorption of wastewater. The three natural South African clinoptilolite samples used in this study were from ECCA Holdings (ESC and EHC samples) and Pratley (PC sample) deposits obtained from Western Cape and KwaZulu-Natal Province respectively. This study revealed that the chemical composition and mineral phases of South African clinoptilolites vary considerably from site to site, even clinoptilolite mined from the same deposit sites. The XRD analyses showed that Pratley clinoptilolite (PC) was the most pure clinoptilolite sample (81.41 %) compared to the purity of EHC (67.88 %) and ESC (44.0 %) sample. The ECCA Holdings untreated clinoptilolite samples contained dense phases such as quartz which was not found in Pratley sample. Quartz was found to be the most dominant impurity in both ECCA Holding sample. The cation exchange capacity (CEC) of ESC, EHC and PC samples were found to be 1.23, 1.81 and 2.90 meq/g respectively and these results were compared to that of XRF analyses. The acid solutions of 0.02 and 1.0 M HCl were used to pretreat natural clinoptilolite to determine the optimum acid concentration and number of extractions required to fully replace the exchangeable cations. The pretreatment results showed that 0.02 M HCl was the optimum acid concentration for acid pretreatment of clinoptilolite samples. Between 7 and 22 extractions were required to remove Na⁺, K⁺, Ca²⁺ and Mg²⁺ without causing much dealumination of the framework. Sodium ion was found to be weakly bound cation in the clinoptilolite framework, since it could be completely exchanged by H⁺ after 7 extractions with 0.02 M HCl acid solution. Potassium ion was found to be strongly bound in the clinoptilolite framework since it could not be completely exchanged during the acid pretreatment process even after 22 extractions. The HRTEM-SAED and BET results showed that ESC, EHC and PC were all polycrystalline and microporous materials respectively. It was found that the adsorption capacity of the treated Pratley clinoptilolite sample was increased by 36 % for NH₄⁺ removal, compared to that of the untreated PC sample. The adsorption study results showed that the pretreatment of clinoptilolite samples using 150 mL volumes of 0.02 M HCl with 7 acid extractions at 25 °C for ESC pretreated and EHC pretreated. The pretreatment of PC sample at 22 extractions could remove high percentage of NH₄⁺ (98.11 %) within a short contact time of 10 min. The pretreated Pratley clinoptilolite sample was found to be the best NH₄⁺ adsorbent (98.11 % NH₄⁺ removal) compared to EHC treated (93.89 % NH₄⁺ removal) and ESC treated (75.00 % NH₄⁺ removal) clinoptilolite samples. However, acid-pretreated Pratley clinoptilolite did not sufficiently remove Cr³⁺ (16.10 %) from synthetic wastewater showing that it is not a good adsorbent for this particular metal ion removal. Despite several studies that have been conducted on clinoptilolite, no study has been carried out on the pretreatment and comparison of sorption capacity of different South African clinoptilolites for the removal of NH₄⁺ from wastewater. This study has been able improve on the acid-pretreatment procedure for clinoptilolite. This study demonstrated that it is not only the acid concentration that is important but also the number of extractions needed to remove all the exchangeable cations from the clinoptilolite framework. This study has also been able to prove that South African clinoptilolite can treated ammonia from wastewater.
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Brady, James Peter. "An examination of the applicability of hydrotalcite for removing oxalate anions from Bayer process solutions." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46165/1/James_Brady_Thesis.pdf.
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Hydrotalcite and thermally activated hydrotalcites were examined for their potential as methods for the removal of oxalate anions from Bayer Process liquors. Hydrotalcite was prepared and characterised by a number of methods, including X-ray diffraction, thermogravimetric analysis, nitrogen adsorption analysis and vibrational spectroscopy. Thermally activated hydrotalcites were prepared by a low temperature method and characterised using X-ray diffraction, nitrogen adsorption analysis and vibrational spectroscopy. Oxalate intercalated hydrotalcite was prepared by two methods and analysed with X-ray diffraction and for the first time thermogravimetric analysis, Raman spectroscopy and infrared emission spectroscopy. The adsorption of oxalate anions by hydrotalcite and thermally activated hydrotalcite was tested in a range of solutions using both batch and kinetic adsorption models.
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Doskočil, Leoš. "Sorpce směsí kovových iontů na přírodním lignitu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216524.
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Sorption of quaternary metal ions (Pb2+, Cu2+, Cd2+ and Zn2+) was carried out on lignite from the South Moravia. Following experiments were tested: kinetic sorption, dependence of sorption on pH, initial concentration, temperature, effect of electrolytes (KNO3 and NaCl) and desorption in deionized water. Sorption studies was carried out in quaternary mixtures and in the case of inicial concentration effect additional in a single-component solution. The batch sorption experiments was used. Sorption time was 24 hour, although concentration of ions was a near equilibrium after two hour. As the optimal pH was determined pH 5. The order of affinity by lignite was obtained Pb >> Cd > Zn > Cu for the sorption of metals in the single-component solution and the order was Pb > Cu > Zn > Cd for the sorption of mixture of metals. The maximum adsorptium capacities from single solutions were for Pb 97,82 mg/g, Cd 60,34 mg/g, Zn 49,88 mg/g and Cu 30,28 mg/g and in the case of ones from mixture solutions were for Pb 39,03 mg/g, Cu 25,94 mg/g, Zn 15,21 mg/g and Cd 5,18 mg/g. Experimental data have been analysed using Langmuir and Freundlich model. Thermodynamic values H°, S° and G° were calculated. Desorption test showed that desorption efficiency is 0–3 %. NaCl had the greatest influence on sorption from electrolytes. On the basis obtained results we can say that metals are binding to lignite in particular due to chemical interactions. Lignite is s suitable as a sorption material for metal ions especially in the field of low concentrations.
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Müller, Carla Cristine. "Avaliação da utilização de carvão ativado em pó na remoção de microcistina em água para abastecimento público." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13615.
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A eutrofização acelerada dos mananciais superficiais, devido aos despejos de águas residuárias não tratadas, vem comprometendo a qualidade das águas utilizadas no abastecimento público. Como conseqüência desse processo, inúmeros registros de florações de cianobactérias são relatados em todo o mundo. Esses microrganismos são potenciais produtores de toxinas, as quais, presentes na água bruta que abastece uma Estação de Tratamento de Água (ETA), precisam ser removidas. As toxinas podem ter efeitos adversos à saúde, podendo causar danos hepatotóxicos, neurotóxicos e dermatotóxicos. A maioria das ETAs brasileiras tratam a água através do processo convencional de tratamento, compreendendo as etapas de coagulação, floculação, sedimentação, filtração e cloração. Esse tratamento é considerado eficiente para remover células de microrganismos, incluindo as cianobactérias. No entanto, suas toxinas não são afetadas, permanecendo na água tratada. Em função disso, alternativas de tratamento devem ser incorporadas ao tratamento convencional, visando remover a hepatotoxina microcistina a concentrações menores ou iguais a 1 μg.L-1, pois esse é o valor máximo permitido (VMP) pela Portaria nº 518/2004, do Ministério da Saúde, a qual define as diretrizes relativas ao controle e vigilância da qualidade da água para consumo humano. Nesse contexto, o objetivo do trabalho foi avaliar a eficiência do carvão ativado pulverizado (CAP), na remoção da cianotoxina microcistina presente na água utilizada para abastecimento público. Cinco amostras de CAP, produzidas a partir de madeira, osso, antracito e coco, foram caracterizadas e, para cada uma, determinadas as Isotermas de Freundlich. As Isotermas mostraram que os CAPs produzidos a partir da madeira apresentaram maior capacidade de remover microcistina. Os residuais de microcistina obtidos nestes ensaios foram ajustados ao modelo de decaimento logarítmico. Assim, para cada CAP, foi estabelecida uma equação geral do processo adsortivo, com a qual foi possível estabelecer dosagens de CAP, variando a concentração de microcistina inicial, para atingir uma concentração residual de 1 μg.L-1. A aplicabilidade da equação foi testada para uma amostra de CAP, em água natural, utilizando o coagulante policloreto de alumínio e concentrações iniciais de microcistina de 1, 10 e 100 μg.L-1. Os resultados mostraram que as dosagens de CAP calculadas foram suficientes para atingir o residual desejado. Além disso, através de ensaios de adsorção, em equipamento de jarros, foram simuladas as etapas de coagulação (utilizando coagulantes sulfato de alumínio e cloreto férrico), floculação, sedimentação e filtração do tratamento convencional para água natural acrescida de 100 μg.L-1 de microcistina. A aplicação do CAP foi realizada em dois pontos do tratamento (1) entrada da água bruta e (2) antes da aplicação do coagulante. A aplicação na entrada da água bruta possibilitou remoção da toxina abaixo do VMP, correspondendo à redução de, aproximadamente, 99% da concentração inicial de toxina. Já no ponto de aplicação antes do coagulante, não foi atingido o VMP. A partir dos estudos aqui realizados, concluiu-se que a melhor maneira de escolher o CAP para remoção de microcistina é a realização de ensaios específicos, como a Isoterma de Freundlich. Para uma remoção eficiente da toxina, o tratamento convencional mostra-se eficaz, desde que a etapa de adsorção seja incorporada ao tratamento.The accelerated surface waters eutrophication, due to non treated residual waters discharges, has been harming the water quality utilized in the public supply. As a consequence of this process, countless records of cyanobacterias’ bloom are reported all over the world. These microorganisms potentially producers of toxins, which, when presented in the raw water that supplies the Water Treatment Plant (WTP), needs to be removed. The toxins can have harmfull effects to the health causing hepatotoxic, neurotoxic and dermatotoxic damage. Most of the Brazilian WTPs treat the water through the conventional water treatment process, covering the stages of coagulation, flocculation, sedimentation, filtering and chlorination. This treatment is considered efficient to remove microorganisms’ cells, including cyanobacterias. However its toxins are not affected, remaining in the treated water. Due to this fact, alternative treatment must be incorporated to the conventional one, trying to remove the microcystin hepatotoxin to concentrations lower or equal to 1 μg.L-1, the maximum allowed value (MAV) according to the Brazilian Ministry of Health Administrative Ruling 518/2004, which defines the rules related to the control and vigilance of the water quality for human consumption. In this context, the objective of the present work was to evaluate the efficiency of the powdered activated carbon’s (PAC), in the removal of the microcystin cyanotoxin present in the water for public supply. Five samples of PAC, made of wood, bone, antracite and coconut, were characterized and, for each one, were determined Freundlich adsorption isotherm . The isotherm showed that the PACs produced from wood presented the highest capacity of microcystin removal. The residuals of microcystin obtained in these tests were adjusted to the logarithmic decay model. Thus, for each PAC, it was established a general equation of the adsorptive process, in order to establish PAC dosages, varying the initial microcystin concentration, to achieve the residual concentration of 1 μg.L-1. The usage of this equation was tested for one sample of PAC, in natural water, using poly-aluminum chloride as a coagulant and the initial concentrations of microcystins of 1, 10 and 100 μg.L-1. The results showed that the dosage of PAC calculated was enough to achieve the desired residual. Besides this, through adsorptive tests, using jar’s equipments, were simulated the stages of coagulation (using alum sulphate and ferric chloride as coagulants), flocculation, sedimentation and filtering of the conventional treatment for natural water and with 100 μg.L-1 of microcystin added. The application of the PAC was performed in two points of the treatment: (1) entrance of the raw water and; (2) before the application of the coagulant. The application in the entrance of the raw water made possible the removal of the toxin under MAV, corresponding to a reduction of, approximately, 99% of the initial concentration of the toxin. Nevertheless, in the point of application before the coagulant, the MAV was not achieved. According to these studies, it was concluded that the best manner of choosing the PAC for microcystin removal is the realization of specific tests like a Freundlich isotherm. For an efficient removal of the toxin, the conventional treatment is efficient, once the adsorption stage is incorporated to the treatment.
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Mohamed, Ziyath Abdul Majeed. "Removal of toxic metals in a multi metal system using sorbents for potential application to urban stormwater treatment." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53193/1/Abdul_Mohamed_Ziyath_Thesis.pdf.
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In the context of increasing demand for potable water and the depletion of water resources, stormwater is a logical alternative. However, stormwater contains pollutants, among which metals are of particular interest due to their toxicity and persistence in the environment. Hence, it is imperative to remove toxic metals in stormwater to the levels prescribed by drinking water guidelines for potable use. Consequently, various techniques have been proposed, among which sorption using low cost sorbents is economically viable and environmentally benign in comparison to other techniques. However, sorbents show affinity towards certain toxic metals, which results in poor removal of other toxic metals. It was hypothesised in this study that a mixture of sorbents that have different metal affinity patterns can be used for the efficient removal of a range of toxic metals commonly found in stormwater.
The performance of six sorbents in the sorption of Al, Cr, Cu, Pb, Ni, Zn and Cd, which are the toxic metals commonly found in urban stormwater, was investigated to select suitable sorbents for creating the mixtures. For this purpose, a multi criteria analytical protocol was developed using the decision making methods: PROMETHEE (Preference Ranking Organisation METHod for Enrichment Evaluations) and GAIA (Graphical Analysis for Interactive Assistance). Zeolite and seaweed were selected for the creation of trial mixtures based on their metal affinity pattern and the performance on predetermined selection criteria. The metal sorption mechanisms employed by seaweed and zeolite were defined using kinetics, isotherm and thermodynamics parameters, which were determined using the batch sorption experiments. Additionally, the kinetics rate-limiting steps were identified using an innovative approach using GAIA and Spearman correlation techniques developed as part of the study, to overcome the limitation in conventional graphical methods in predicting the degree of contribution of each kinetics step in limiting the overall metal removal rate.
The sorption kinetics of zeolite was found to be primarily limited by intraparticle diffusion followed by the sorption reaction steps, which were governed mainly by the hydrated ionic diameter of metals. The isotherm study indicated that the metal sorption mechanism of zeolite was primarily of a physical nature. The thermodynamics study confirmed that the energetically favourable nature of sorption increased in the order of Zn < Cu < Cd < Ni < Pb < Cr < Al, which is in agreement with metal sorption affinity of zeolite. Hence, sorption thermodynamics has an influence on the metal sorption affinity of zeolite. On the other hand, the primary kinetics rate-limiting step of seaweed was the sorption reaction process followed by intraparticle diffusion. The boundary layer diffusion was also found to limit the metal sorption kinetics at low concentration. According to the sorption isotherm study, Cd, Pb, Cr and Al were sorbed by seaweed via ion exchange, whilst sorption of Ni occurred via physisorption. Furthermore, ionic bonding is responsible for the sorption of Zn. The thermodynamics study confirmed that sorption by seaweed was energetically favourable in the order of Zn < Cu < Cd < Cr . Al < Pb < Ni. However, this did not agree with the affinity series derived for seaweed suggesting a limited influence of sorption thermodynamics on metal affinity for seaweed.
The investigation of zeolite-seaweed mixtures indicated that mixing sorbents have an effect on the kinetics rates and the sorption affinity. Additionally, the theoretical relationships were derived to predict the boundary layer diffusion rate, intraparticle diffusion rate, the sorption reaction rate and the enthalpy of mixtures based on that of individual sorbents. In general, low coefficient of determination (R2) for the relationships between theoretical and experimental data indicated that the relationships were not statistically significant. This was attributed to the heterogeneity of the properties of sorbents. Nevertheless, in relative terms, the intraparticle diffusion rate, sorption reaction rate and enthalpy of sorption had higher R2 values than the boundary layer diffusion rate suggesting that there was some relationship between the former set of parameters of mixtures and that of sorbents. The mixture, which contained 80% of zeolite and 20% of seaweed, showed similar affinity for the sorption of Cu, Ni, Cd, Cr and Al, which was attributed to approximately similar sorption enthalpy of the metal ions. Therefore, it was concluded that the seaweed-zeolite mixture can be used to obtain the same affinity for various metals present in a multi metal system provided the metal ions have similar enthalpy during sorption by the mixture.
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Du, Toit Elizabeth Louisa. "The Rate inhibiting effect of water as a product on reactions catalysed by cation exchange resins formation of mesityl oxide from acetone as a case study /." Diss., Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-02272004-140347.
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CASTRO, Mara Lucia Lemke de. "Retenção de metais pesados em solos agricultáveis do Estado de Goiás." Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/2679.
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Previous issue date: 2009-07-31The intensification of the use of land for farming has caused great concern, mainly due to the impacts that these activities are causing the environment, particularly with regard to it s contamination by chemicals. The application of chemicals and waste ground and in several, or in plants in order to take agronomically solid waste, improve productivity and increase agricultural production has been growing in the practices of cultivation. The form of improper disposal of waste in the soil, without any control of dose and form of application, and without knowledge of their ability to assimilate the different soil types, possibly predisposing the occurrence of contamination and pollution along the profile these soils and may reach the water table and contaminate groundwater. This work aimed the analysis of the retention of some heavy metals in Ultisol, Oxisol Typic Acrustox, Quartzipsamment and Kandic Oxisol found in savannah soil of the Goiás. Heavy metals in tests were Cadmium (Cd+2), lead (Pb+2), copper (Cu+2), chromium (Cr+3 and Cr+6), nickel (Ni+2) and zinc (Zn+2). The sorption of the heavy metals in soil was evaluated by batch method and described by potential and linear models of the Freundlich isotherm. For the establishment of sorption isotherm were added in 5,0 cm3 of soil and 50,0 cm3 of solution containing the heavy metal being assessed with different concentrations within the limits acceptable soil. The potential and linear sorption isotherm submitted a good adjusted to describe the behavior of adsorption of heavy metals in different classes of soil studied. The detention of heavy metals in descending order was the Ultisol: Cr+3 > Cr+6 > Ni+2 > Zn+2 > Cu+2 > Pb+2 > Cd+2; Oxisol Typic Acrustox: Cr+3 > Cr+6 > Ni+2 > Cu+2 > Cd+2 > Zn+2 > Pb+2; Quartzipsamment: Cr+6 > Cr+3 > Cu+2 > Pb+2 > Ni+2 > Zn+2 > Cd+2; Kandic Oxisol: Cr+3 > Cr+6 > Pb+2 > Cu+2 > Zn+2 > Ni+2 > Cd+2. The Quartzipsamment presented a less retention metal comparison other classes of soil, and therefore more vulnerable to contamination of groundwater.
A intensificação do uso das terras para fins agropecuários tem causado grande preocupação, devido, principalmente, aos impactos que essas atividades vêm causando ao meio ambiente, sobretudo no que diz respeito à sua contaminação por substâncias químicas. A aplicação de produtos químicos e de resíduos diversos no solo e, ou, nas plantas, com o propósito de aproveitar agronomicamente resíduos sólidos, melhorar a produtividade e aumentar a produção agrícola, tem sido crescente nas práticas de cultivo. A forma inadequada de disposição de resíduos no solo, sem qualquer controle das doses e da forma de aplicação, e sem o conhecimento da capacidade de sua assimilação pelos diferentes tipos de solos, possivelmente, predispõem a ocorrência de contaminação e de poluição ao longo do perfil desses solos, podendo alcançar o lençol freático e contaminar as águas subterrâneas. Objetivou-se com este trabalho a análise da retenção de alguns metais pesados nas classes de solo Argissolo Vermelho Eutrófico, Latossolo Vermelho Acriférrico, Neossolo Quartzarênico e Nitossolo Vermelho Eutroférrico encontrados em áreas de cultivo do Estado de Goiás. Os metais tóxicos avaliados nos ensaios de sorção foram cádmio (Cd+2), chumbo (Pb+2), cobre (Cu+2), cromo (Cr+3 e Cr +6), níquel (Ni+2) e zinco (Zn+2). A sorção dos metais foi avaliada pelos modelos potencias e lineares da isoterma de Freundlich. Para o estabelecimento de isotermas de sorção foram adicionados em 5,0 cm3 de solo e 50,0 cm3 de solução contendo o metal tóxico a ser avaliado com diferentes concentrações, respeitando os limites aceitáveis. As isotermas de sorção potencial e linear apresentaram um bom ajuste para descrever o comportamento de adsorção dos metais tóxicos nas diferentes classes de solos estudadas. A sequência da retenção dos metais tóxicos em ordem decrescente foi, para o Argissolo Vermelho Eutrófico: Cr+3 > Cr+6 > Ni+2 > Zn+2 > Cu+2 > Pb+2 > Cd+2; Latossolo Vermelho Acriférrico: Cr+3 > Cr+6 > Ni+2 > Cu+2 > Cd+2 > Zn+2 > Pb+2; Neossolo Quartzarênico: Cr+6 > Cr+3 > Cu+2 > Pb+2 > Ni+2 > Zn+2 > Cd+2; Nitossolo Vermelho Eutroférrico: Cr+3 > Cr+6 > Pb+2 > Cu+2 > Zn+2 > Ni+2 > Cd+2. O Neossolo Quartzarênico apresentou uma menor retenção de metais em comparação às demais classes de solo, sendo, portanto, mais vulnerável à contaminação das águas subterrâneas.
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Godongwana, Ziboneni Governor. "Highly selective mesoporous sorbents for mercury removal from industrial wastewater." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8398_1320306023.
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The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g â1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route.
Book chapters on the topic "Freundlich Isotherm"
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Van der Bruggen, Bart. "Freundlich Isotherm." In Encyclopedia of Membranes, 834–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-44324-8_254.
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Van der Bruggen, Bart. "Freundlich Isotherm." In Encyclopedia of Membranes, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40872-4_254-3.
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Horn, A. L., R. A. Düring, and S. Gäth. "Sorption of Cd in Soils: Pedotransfer Functions for the Parameters of the Freundlich Sorption Isotherm." In Biogeochemical Investigations of Terrestrial, Freshwater, and Wetland Ecosystems across the Globe, 61–71. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-007-0952-2_5.
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"freundlich sorption isotherm." In The Fairchild Books Dictionary of Textiles. Fairchild Books, 2021. http://dx.doi.org/10.5040/9781501365072.6605.
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Van Hoang, Nguyen. "Soil-Skeleton and Soil-Water Heavy Metal Contamination by Finite Element Modelling With Freundlich Isotherm Adsorption Parameters." In Heavy Metals - New Insights [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101828.
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World research results indicate that untreated leachate contains high contents of heavy metals (HM) that are likely to pollute the soil and groundwater (GW) environment and contribute to the increase of HMs in soil and GW. The Freundlich isotherm adsorption parameters are essential to soil input parameters for modelling of HMs’ transport to access the soil skeleton and soil pore water contamination by HMs. Finite element (FE) modelling of advection-dispersion transport of HMs by GW movement along with Freundlich isotherm adsorption parameters which continuously change with space in the model domain and with time is sophisticated to accurately evaluate the HMs’ concentrations in soil skeleton and pore water. The chapter describes the background of the existing isotherm adsorption theory, the adaptation of the Freundlich isotherm adsorption in the soil skeleton and soil pore water contamination by HMs, method of determination of the Freundlich isotherm adsorption parameters, the FE procedure of modelling of advection-dispersion transport of HMs by GW movement in general and along with Freundlich isotherm adsorption parameters in particular. A case study modelling has been demonstrated.
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"1. On the Theory of the Freundlich Adsorption Isotherm." In Selected Works of Yakov Borisovich Zeldovich, Volume I, 58–67. Princeton University Press, 1992. http://dx.doi.org/10.1515/9781400862979.58.
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Proctor, Andy, and J. Toro-Vazquez. "The Freundlich Isotherm in Studying Adsorption in Oil Processing." In Bleaching and Purifying Fats and Oils, 209–19. AOCS Publishing, 2010. http://dx.doi.org/10.1201/b10513-11.
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Chen, Jun, Sisi Cao, Jiali Wang, Zhaoming Chen, Jie Jin, and Yang Zhang. "Sludge Activated Carbon Prepared by High Dehydration and Carbonization Equipment and Adsorb Phosphorus in Wastewater." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220388.
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Sludge activated carbon (SAChdc) was prepared by high dehydration & carbonization equipment and used for adsorption phosphorus in wastewater. The sludge can be dehydrated until water content below 60%, then carbonized by the high dehydration & carbonization equipment. The SAChdc used as absorbent in phosphorus of wastewater treatment. The experimental results showed that the adsorption capacity of phosphorus could reach 4.598 mg/g, and adsorption rate was above 91%, the pseudo-second-order kinetic equation and Freundlich isotherm model could describe the phosphorus adsorption process of SAChdc. SAChdc prepared and used as absorbent realized the sludge harmless and resource utilization.
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Belekar, R. M., and S. J. Dhoble. "The Fluoride Adsorption Isothermal Studies of Activated Alumina Modified with Different Materials: A Critical Review." In Water Pollution Sources and Purification: Challenges and Scope, 28–74. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050684122010005.
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: Fluoride in drinking water has become a global problem that has a profound effect on teeth and bones, fostering various health problems. Adsorption is a potential defluoridation technique because of flexibility, cost-effectiveness, environmental friendliness, simplicity in design, relative ease of operation, and capability of producing high water quality. Although activated alumina is an appropriate adsorbent, it has a narrow favorable pH range, a tendency to form toxic aluminum fluoride complexes, and the problem of aluminum metal leaching. This article critically reviews the applicability of activated alumina and its modification by metal oxides, rare earth elements, organic materials, alkaline earth metals, and acid treatment. The effect of process parameters like pH, contact time, adsorbent dose, initial fluoride concentration, and the presence of coexisting ions on the adsorption capacity of fluoride ions is discussed. The adsorption reaction rates were discussed by fitting various rate models into the experimental data and the model equations. The adsorption isotherm models like Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich tested on the adsorption equilibrium data to identify the best fit model for adsorption isotherm are discussed in this chapter. The chapter finally discusses the advantages, disadvantages, and future prospects of all the adsorbents in order to improve their fluoride removal capacity.
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Agougui, Hassen, Youssef Guesmi, and Mahjoub Jabli. "Preparation of Functionalized Hydroxyapatite with Biopolymers as Efficient Adsorbents of Methylene Blue." In Dyes and Pigments - Novel Applications and Waste Treatment. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95347.
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In this study, we reported the synthesis of hydroxyapatite modified with biopolymers as λ-carrageenan and sodium alginate, which could be used as effective adsorbents of cationic dyes. Evidence of chemical modification was proved through chemical analysis, Fourier Trans-form Infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and specific surface area. The adsorption process was studied using methylene blue as representative cationic dye. The adsorbed quantity reached, at equilibrium, 142.85 mg/g and 98.23 mg/g using hydroxyapatite-sodium alginate and hydroxyapatite-(λ-carrageenan), respectively. However, it does not exceed 58.8 mg/g in the case of the unmodified hydroxyapatite. The adsorption of methylene blue using hybrid materials complied well with the pseudo-second-order suggesting a chemi-sorption. Freundlich and Langmuir isotherm described well the adsorption mechanism of the hydroxyapatite-(λ-carrageenan) and hydroxyapatite-sodium alginate, respectively. The high capacities of MB removal obtained in this study suggest the potential use of these materials in the treatment from wastewaters.
Conference papers on the topic "Freundlich Isotherm"
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Mohd Aji, Aminah Qayyimah, Belladonna Maulianda, Dzeti Farhah Mohshim, Khaled Abdalla Elraeis, and Ku Esyra Hani Ku Ishak. "Supercritical Methane Adsorption in Shale: Isothermal Adsorption and Desorption of Eagle Ford Shale Gas." In Offshore Technology Conference Asia. OTC, 2022. http://dx.doi.org/10.4043/31615-ms.
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Abstract Gas adsorption-desorption highly affect gas storage and production behaviour in shale nanopores. The study of methane adsorption isotherm in shale has been extensively conducted experimentally. The shale compositions and reservoir conditions prominently control the adsorption capacity of methane. However, to date, there is a lack of discussion on the effect of heterogeneous TOC towards the adsorption isotherm and comparison with adsorption isotherm modelling. This study used the gravimetric method for supercritical methane adsorptions - desorption isotherms measurements. Isotherms measurements were conducted with three shale samples with various TOC values (9.67, 13.9, and 15.4 wt.%) from the Eagle Ford formation at pressure up to 10 MPa and temperature at 120 °C. The isotherms gathered were fitted with standard adsorption-desorption isotherm models, Langmuir, Freundlich and extended Sips to test the applicability of these models depicted the adsorption of supercritical methane. The results show that EF C with the highest TOC content (15.4 wt.%) has the highest adsorption-desorption methane capacity, more than 0.7 mmol/g, compared to other samples. The composition differences between these samples indicate that the organic contents were likely a major controlling factor of the adsorption capacities obtained. The TOC provides a higher surface area for adsorption to occur. Thus, a higher adsorption-desorption capacity was observed through this study. On the other hand, the adsorption and desorption curves did not intercept due to the hysteresis caused by the capillary condensation. The significant binding capacity of the shale surface for methane gas molecules leads to the hysteresis observed during methane desorption. It was observed that the Freundlich model was the most accurate adsorption model in describing the adsorption-desorption behaviour with tested shales with average R2 more than 0.90 and ARE (%) less than 10 % compared to other models with 15.8 % (Langmuir) and 18.9 % (Sips). This study also proved the influence of organic matter on predicting the adsorption-desorption capacity with adsorption isotherms highlighting the importance of modelling the TOC of shale with adsorption isotherm to determine the adsorption-desorption properties.
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Patiha, Maulidan Firdaus, Fitria Rahmawati, Sayekti Wahyuningsih, and Triana Kusumaningsih. "Freundlich adsorption isotherm in the perspective of chemical kinetics (II); rate law approach." In THE 14TH JOINT CONFERENCE ON CHEMISTRY 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0005342.
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Sharma, Alfa, Yogendra Kumar, and Parasharam M. Shirage. "Synthesis of humidity sensitive zinc stannate nanomaterials and modelling of Freundlich adsorption isotherm model." In DAE SOLID STATE PHYSICS SYMPOSIUM 2017. Author(s), 2018. http://dx.doi.org/10.1063/1.5028726.
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Liu, Qingqing, and Xiaoyan Li. "Study on Adsorption of U(VI) From Aqueous Solution by Activated MgO." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67922.
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The activated MgO was synthesized by microwave homo-precipitator method and characterized by SEM, EDS and FT-IR methods. It was used to adsorption of U(VI) from aqueous solution with batch system. The paper discussed the effect of pH, temperature, contact time, adsorbent dose and initial U(VI) concentration on the adsorption. The results showed that activated MgO has good adsorption capacity for U(VI), the removal rate and equilibrium adsorption capacity reached 83.5% and 84.04mg·g−1 at pH 5.0, 15mg dose and 313K,respectively. The adsorption kinetics of U(VI) onto activated MgO were better fitted with pseudo-second-order kinetic.The adsorption isotherm data were fitted well to Freundlich isotherm model.The thermodynamic parameters showed that the adsorption process is endothermic and spontaneous.
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Alsaba, Wisam Hussam, Raafat Alenany, and Mohammed Zamzam. "Using Synthetic Resins for Removal of Emulsified Oil from Produced Water." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0103.
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In this study, adsorption of emulsified oil in produced water was experimented using synthetic resins. Adsorbent dosage, contact time, initial oil concentration, and PH were the main key parameters evaluated for Optipore L493, Amberlite IRA 958, Amberlite XAD 7 and Lewatit AF 5. Oil removal rates have reached up to 98% using AF 5, XAD 7 and L493, while they are lesser than 25% for IRA 958. Isotherm data were fitted using Langmuir, Freundlich, Toth, Flory Huggins and Dubinin-Radushkevich models. Adsorption isotherms for XAD 7 and L 493 were best fitted using Langmuir model, whereas AF 5 curves were best fitted using Dubinin-Radushkevich. Kinetic data describing the rate of adsorption for each resin were studied and fitted using pseudo-first and second order equations in addition to intraparticle diffusion models. The experimental results were best-fitted using pseudo second order kinetics. The obtained results confirm the applicability of the resins for the removal of oil from produced water.
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Cajucom, Ernesto Jr S., and Lolibeth V. Figueroa. "SURFACE MODIFICATION OF CANARIUM OVATUMENGL.(PILI) SHELL AS ADSORBENT OF LEAD(Pb2+) FROM AQUEOUS SOLUTION." In International Trends in Science and Technology. RS Global Sp. z O.O., 2021. http://dx.doi.org/10.31435/rsglobal_conf/30032021/7476.
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This study was carried out to investigate the efficiency of raw pili shell (RPS) and the surface modified pili shell using EDTA (EMPS) and oxalic acid (OMPS). A comparative study on the adsorption capacity of the adsorbents was performed against lead (Pb2+) from aqueous solution. The adsorbents were characterized by FTIR, which showed higher peak of adsorption bands of carboxylic groups on the acid modified pili shells. Scanning electron microscope orSEM was also used to describe the surface morphology of the adsorbents. The linear form of Langmuir and Freundlich models were applied to represent adsorption data. The calculated equilibrium data of Pb (II) best fitted to Langmuir compare to Freundlich isotherm model with maximum adsorption capacity (qmax) of 27.03 mg/g and 45.45 mg/g using EMPS and OMPS, respectively. Kinetic sorption models were used to determine the adsorption mechanism and the kinetic data of all the adsorbents correlated (R2=1) wellwith the pseudo second order kinetic model. Among the three adsorbents, OMPS shown higher percent removal of lead compared to RPS and EMPS. The large adsorption capacity rate indicated that chemically modified pili shell in present study has great potential to be used as a cost-effective adsorbent for the removal of lead ions from the water.
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Boussouga, Youssef-Amine, Marina Valentukeviciene, and Ramune Zurauskiene. "Research on Fluoride Removal from Membranes Rejected Water." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.071.
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The excess of fluoride in water intended for human consumption can cause some problems in health of consumers from concentrations over than 1.5 mg/L. A detailed study has been carried out for the removal of fluoride from concentrated rejected water overcoming the drawback of membrane processes by using sorption techniques. Opoka mineral which is a natural sorbent and polonite have been chosen and valorized in this present work as fluoride sorbents for rejected water by membranes of the water treatment plant. These sorbents have been selected in order to reduce the treatment cost and to meet the standards of rejected water especially in term of fluoride. Opoka sorbent and polonite have shown effective results for fluoride removal from rejected water with efficiency over than 77%. In order to understand the sorption phenomenon and to validate the results with sorbents, we have applied experimental data on Freundlich Isotherm and SEM microscopic technique.
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Seniūnaitė, Jurgita, Rasa Vaiškūnaitė, and Kristina Bazienė. "Mathematical Modelling for Copper and Lead Adsorption on Coffee Grounds." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.007.
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Research studies on the adsorption kinetics are conducted in order to determine the absorption time of heavy metals on coffee grounds from liquid. The models of adsorption kinetics and adsorption diffusion are based on mathe-matical models (Cho et al. 2005). The adsorption kinetics can provide information on the mechanisms occurring be-tween adsorbates and adsorbents and give an understanding of the adsorption process. In the mathematical modelling of processes, Lagergren’s pseudo-first- and pseudo-second-order kinetics and the intra-particle diffusion models are usually applied. The mathematical modelling has shown that the kinetics of the adsorption process of heavy metals (copper (Cu) and lead (Pb)) is more appropriately described by the Lagergren’s pseudo-second-order kinetic model. The kinetic constants (k2Cu = 0.117; k2Pb = 0,037 min−1) and the sorption process speed (k2qeCu = 0.0058–0.4975; k2qePb = 0.021–0.1661 mg/g per min) were calculated. After completing the mathematical modelling it was calculated that the Langmuir isotherm better reflects the sorption processes of copper (Cu) (R2 = 0.950), whilst the Freundlich isotherm – the sorption processes of lead (Pb) (R2 = 0.925). The difference between the mathematically modelled and experimen-tally obtained sorption capacities for removal of heavy metals on coffee grounds from aqueous solutions is 0.059–0.164 mg/l for copper and 0.004–0.285 mg/l for lead. Residual concentrations of metals in a solution showed difference of 1.01 and 0.96 mg/l, respectively.
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Khramov, Dimitri, and Evgeny Barmatov. "Fate of Emulsifier in Invert Emulsion Drilling Fluids: Hydrolysis and Adsorption on Solids." In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204290-ms.
Full textAbstract:
Abstract Emulsifier concentration in SBM is an important factor of drilling fluid stability. Proper concentration of amidoamine emulsifier is imperative for controlling low fluid loss and maintaining emulsion stability. This study investigates the physical and chemical interactions between emulsifier and other additives and describes the processes by which emulsifier is depleted from the drilling fluid. Three main pathways of emulsifier consumption are identified: emulsifier adsorption on solids found in drilling fluids and low gravity solids (LGS), chemical degradation, and to stabilize the invert emulsion. Design of experiments model and analytical procedure based on 1H NMR (nuclear magnetic resonance) spectroscopy was used to quantify the required emulsifier concentration in Non-Aqueous Fluid system (NAF). Additionally, model systems were used to estimate the excess of emulsifier, evaluate the emulsifier losses due to alkaline hydrolysis at elevated temperature, and measure adsorption of emulsifier on barite and various LGS types. Calculations for emulsifier depletion based on model systems were correlated to performance of formulated drilling fluids for verification. Typical emulsifier requirement in high performance NAF is 8-12 pounds per barrel (ppb). Majority of the emulsifier is adsorbed on weighting agents (barite) and rheology modifiers (clays), which are used to formulate NAF, that contribute to their effective dispersion in the solution and control fluid rheology. The adsorption process is found to be sensitive to the emulsifier concentration, solids mineralogy, wetting agent and temperature. Analytical Langmuir-Freundlich isotherm was used to describe adsorption data and estimate the adsorption capacity of the system. The emulsifier degradation pathway is another important factor of emulsifier consumption; however, emulsifier degradation at 250°F is not significant. While NAF are generally run ‘rich’ to mitigate depletion and maintain fluid stability, adsorption onto minerals will become an issue especially at high LGS concentration. These results will be greatly beneficial in the further development of NAF drilling fluid formulations and will assist field engineers in understanding the effect excess emulsifier will have on the drilling fluid and enable them to more effectively control the fluid properties under variations in emulsifier and LGS concentration during drilling.
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Qifeng, Qin, and Li Xiaoyan. "Study on Active Magnesium Oxide Adsorption Properties of Sr (II) in Aqueous Solution." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67917.
Full textAbstract:
The active magnesium oxide (AMO) was synthesized by homogeneous precipitation method with microwave and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and infrared spectroscopy (FTIR). Adsorption of Sr(II) by AMO was investigated under the effect of AMO dosages, pH of solution, temperature and contact time and analyzed the kinetics and thermodynamics characteristics. The results showed that AMO has very good adsorption capacity on Sr(II) in aqueous solution,When pH of solution is 8.0, the solid-liquid ratio is 0.25 g·L−1, initial Sr(II) concentration is 50mg·L−1, the contact time is 80 min at 298K, the removal rate and adsorption capacity reached 98.29% and 187.5 mg·g−1, respectively. Kinetic and thermodynamic results indicate that adsorption behavior of Sr(II) by AMO fitted well with pseudo-second-order model and the Freundlich isothermal model. Adsorption thermodynamic parameters showed that the process of adsorption is spontaneous and endothermic.