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Dissertations / Theses on the topic 'Heavy metal chemistry'
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1
Adams, C. "The chemistry of some heavy transition metal organometallics." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595343.
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The thesis is concerned with the synthesis of some new organometallic and co-ordination compounds of platinum (in the main), tungsten and gold. Chapter 1 contains an overview of the field of platinum σ - acetylide chemistry from its origins to the present day, looking at structural types and the properties of this kind of compound. Chapter 2 contains details of the synthesis and characterisation of some novel bipyridyl containing platinum acetylides of the form cis-(tbu2bipy)Pt(-C≍C-R)2 (where R = Ph.p-C6H4-CH3, SiMe3, p-C6H4-NO2 and tbu2bipy = 4,4'-bis(tbutyl)-2,2'-bipyridine), looking at the IR, UV and NMR spectroscopy of these compounds and at the crystal structure of a representative member of this class. Some EHMO calculations pertaining to the HOMO and the LUMO of these compounds are presented, and EPR and in-situ spectroelectrochemical experiments that support these MO calculations are detailed. There is also a report on and a discussion of the attempted synthesis of some molecular squares. Chapter 3 looks at the use of the compounds detailed in Chapter 2 as chelating agents for copper and silver thiocyanate, tetrafluoroborate and perchlorate salts. The crystal structures of representatives of these are investigated, as is their electro-and spectro- chemical behaviour. Chapter 4 contains details of some new bis-pyridyl platinum acetylides of formula (npy)2Pt(-C≍C-R)2 (npy = 4-(5-nonylpyridine)), in which the platinum atom has mutually trans - acetylide ligands, and some polymeric species formed from these monomeric precursors and bis - acetylides containing chromophoric groups (bithiophene, terthophene and 9-fluorenone) are presented, and their optical and electronic properties investigated.
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Gillett-Kunnath, Miriam M. "Heavy alkaline earth metal amides: Synthetic and structural investigations." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.
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Steinbaugh, Gregory E. "Heavy metal Ion transport utilizing natural and synthetic ionophores." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1189785736.
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Galati, Rosa. "Synthesis, structure and properties of heavy metal pyrochlore oxides." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/173963/.
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Many interesting and often exotic magnetic phenomena have been observed over the past twenty years in the family of the heavy metal pyrochlore oxides, A2B2O6O’. In these systems, competing interactions are common and tend to emerge mainly at low temperatures. Magnetic properties are related to the contribution of d orbitals that transition metal (TM) offer and their interplay with the positive contribution coming from the cation sitting on the A site. The work described in this thesis explores the effects of chemical substitution of the A site cation on the symmetry and the properties of a number of pyrochlores containing TM of the second and third transition row, such as Ir, Ru, Mo and Os. Depending if this site is fully occupied and on the radius size the behaviour of the resulting material can change significantly. The defect pyrochlore family AOs2O6 (A = Cs, Rb, K) was studied in detail following the attention that its members attracted for having been the first materials, belonging to this subgroup, to exhibit superconducting properties [1, 2, 3] and for the diversity in their properties. In these compounds, the smaller the ionic radius of an element, the weaker is the bond to the structure. As a result, the temperature dependence of their energy becomes quite different from normal lattice vibrations and gives interesting low temperature behaviours. The effect of replacing the weak bonded potassium ions on the structures and superconducting properties of the AOs2O6 phases has also been studied. The ability to exchange the A-type in pyrochlores is well known and leads to applications for example in nuclear clean-up. Thus the ion exchange of K+ by smaller cations such as Li+ or Na+ has been investigated with the aim of synthesising compounds which cannot be obtained by direct synthesis. New defect pyrochlore materials, AA’Os2O6 (A’ = Li+, Na+) have been synthesised together with hydrated derivatives, AA’OsO6.nH2O. Parent materials were obtained by ion exchange in non-aqueous solvents under strictly dry conditions. A Ba-based osmium oxide pyrochlore, Ba(Os2O6)2.H2O was also synthesised, for the first time, from the K-osmate starting material by ion-exchange methods in aqueous medium. In this work, diffraction techniques, X- ray and neutron powder diffraction, were employed and found suitable for detecting the change in cation and anion location and general structure investigation.These structural descriptions are correlated with the measured superconducting properties and theoretical descriptions of variations in the Tc in these systems as a function of cation size and rattling.
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Dallin, Paul Howard. "Novel spectroscopic techniques applied to metal cluster compounds." Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291953.
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Gao, Kezhong. "Interaction between peat, humic acid and aqueous heavy metal ions." Thesis, Liverpool John Moores University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337798.
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Read, Tania L. "Development of boron doped diamond electrodes for heavy metal detection." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/83225/.
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Due to their high toxicity and prevalence in natural waters, trace heavy metals are of great concern to environmental analysts. The development of techniques with the ability to detect and quantify ppb levels of heavy metal species in the environment, without the need for sample removal and pretreatment, is therefore a key interest. Popular methods for heavy metal detection such as X-ray Fluorescence (XRF) provide easy elemental identification but lack the low detection limits desirable, whereas electrochemical methods can provide low detection limits but signal assignment in complex samples is often difficult. In addition to this, one of the biggest issues with current methods is the non-ideal nature of the environmental matrices for analysis, for example where the pH of natural waters is usually in the range 6-9; Heavy metal analysis is generally improved under acidic conditions. In this thesis a number of methods are developed with the aim of addressing these issues and moving towards in situ heavy metal detection. Electrochemistry offers an ideal platform for in situ use due to its ease of portability and low power requirements, furthermore the use of conductive boron doped diamond (BDD) electrodes provide a robust sensor resistant to both corrosion and fouling and therefore ideal for long term environmental deployment. Herein BDD dual electrode systems are developed and employed for electrochemical heavy metal detection with simultaneous control of local pH. Fabrication and electrochemical characterisation of these devices is described and compared to finite element simulation. It is shown that using such devices it is possible to control the local pH of a solution even in solutions containing up to 10 mM buffer, allowing manipulation of heavy metal (Hg and Cu) speciation and therefore improved electrochemical detection. The development of all-diamond ring disc electrodes is described; by growing BDD electrodes in insulating diamond, robust well-sealed devices where the sensor and its housing both exhibit the desirable mechanical properties of diamond can be produced. Finally, the newly developed Electrochemical XRF (EC-XRF) technique is optimised and applied to the detection of Cd and Hg.
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Morris, Leigh John. "Photochemical studies of some heavy transition metal compounds with catalytic potential." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343436.
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Ngule, Chrispus M. Jr. "In Vitro Adsorption of Heavy Metals Using Metal-Organic Frameworks." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1597664070125999.
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Amador, Ana Isabel Ojeda. "Synthesis of multicomponent heavy alkali metal amide systems and extensions to zirconium chemistry." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27849.
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Due to the nature of the work undertaken during the course of this PhD, the results of this thesis will be broken down into three sections. The first section comprises Chapter 1 and includes an introduction on reported homometallic lithium, sodium and potassium salts of the bulky utility amines [HMDS(H), TMP(H) and DA(H)]. The second section, Chapter 2−Chapter 5, includes the achieved results obtained during the course of this PhD work based on the homometallic alkali metal building block amides. The third section involves an introduction on zirconium species and their applications in specific reactions, along with the solid and solution state studies of zirconocene species combined with alkali metal and alkali earth metal amides obtained during this work. Chapter 2 includes a deep discussion in the solid state of NaHMDS systems capturing Na halide units in the presence of a multidentate Lewis base donor ligand, taking on different structural guises depending on the denticity of the ligand of choice. This topic is currently a hot topic in organometallic chemistry, being lithium amide congeners have already been characterised. This study allows a deep examination of these structures and confirms the AM-amide/AM-halide interaction to exist in sodium chemistry as well. Chapter 3 unveils the structural chemistry of the utility base, potassium hexamethyldisilazide (KHMDS), which is explored through the incorporation of different dentate ligands into its structure. This study containing the solid state characterisation of homometallic potasium amides being a necessary preface to the bimetallic work. Having investigated the solid state structure of homometallic potasium systems, it was also deemed important to study heavier alkali metal building blocks. Thus, Chapter 4 includes the structural characterisation of specific amine adducts of the heavy alkali metal amide CsHMDS, which is recently being used in important organic transformations. Having investigated homometallic systems of heavy bulky amides, it was also deemed important to synthesise and characterise heterobimetallic species containing early and heavy alkali metal species adding to the solvent-coordination free heterobimetallic alkali metal building blocks. Due to the usage that sodium hexamethyldisilazide (NaHMDS) is gaining as a proton abstractor reagent in organic synthesis, akin to its homometallic lithium congener LiHMDS, Chapter 5 includes the synthesis and structural characterisation of three novel adducts of NaHMDS by using the chiral amine N,N,Nʹ,Nʹ-(1R,2R)-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] and the synthetically important tridentate ligand PMDETA allowing the development of a homologues series of [(R,R)-TMCDA]- and PMDETA-solvated NaHMDS complexes. Having successfully synthesised solvated homo- and hetero-bimetallic alkali metal salts of HMDS, the attention turned to the possibility of incorporating the tetravalent transition metal zirconium into these systems to afford homo- and hetero-bimetallic HMDS-containing zirconocene species (Chapter 6).
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Beesley, Luke. "Carbon in urban, brownfield and heavy metal contaminated soils." Thesis, Liverpool John Moores University, 2010. http://researchonline.ljmu.ac.uk/5957/.
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This thesis is comprised of a collection of work on urban, brownfield and heavy metal contaminated soils carried out within the North West of England from March 2007 to December 2009. Field and laboratory based experiments were used to determine the amount of carbon stored in urban soils and fluxes of dissolved organic carbon and soil respiration. The effects of added organic amendments on carbon storage and mobility as well as the onward implications to heavy metals and arsenic mobility and the impact of earthworms on these processes were also investigated. A city-wide topsoil survey of parkland and road verges in Liverpool showed that carbon storage ranged from < 3 to > 10 kg total organic carbon m-2 whilst physico-chemical characteristics and heavy metal and arsenic concentrations also varied considerably. The abundance oftechnogenic material restricted organic carbon storage and flux to the upper 30 cm of an inner city lawn soil studied in greater detail. Brownfield soil carbon storage and fluxes were enhanced by adding a small amount of green waste compost to these soils but large applications did not greatly increase carbon storage further. Enhanced losses of carbon by dissolved organic carbon leaching and increased soil respiration rates were consequences of greenwaste compost additions, although these effects were highly seasonal, occurring in greatest magnitude at the warmest periods of the year. Proportionately, the annual losses of carbon to soil respiration were far greater than those to dissolved organic carbon. An amendment consisting predominantly of woody material and a biochar amendment had a lower impact than composted greenwaste on dissolved organic carbon mobility, and the co-mobilisation of heavy metals and arsenic in a soil from a previously heavily industrialised centre of population. Earthworms reduced dissolved organic carbon when inoculated with compost and biochar amended soil, but increased this soluble fraction of carbon in woody amended soils, with attendant consequence to trace metal and arsenic mobility. Zinc and cadmium mobility were largely independent of changes in soluble carbon, but arsenic, copper and lead were heavily influenced by added carbon. Biochar amendment proved very effective in reducing concentrations of soluble cadmium and zinc in a heavy metal contaminated soil by adsorption, as well as having the added benefit of reducing total and bioavailable polycyclic aromatic hydrocarbon (PAH) concentrations. It is concluded that carbon storage in urban soils can potentially be increased by applying organic amendments, although longer-term carbon storage may only be substantially enhanced with repeated applications of amendments. However, in urban soils with significant residual pollution, it can be questioned whether this practice is environmentally sound, regarding mobilisation of potentially harmful trace elements. Biochar and larger woody fraction amendments to soils may be more efficacious.
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Smith, Erin. "Heavy Metal Accumulation in Seagrasses in Southeastern Florida." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/474.
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Seagrass beds are among the most ecologically important systems in the marine environment. They provide the primary production to nearby coral reef and mangrove communities, and seagrasses comprise a large component of the diets of many marine organisms including fishes, small invertebrate species, and many protected species such as manatees and sea turtles. This consumption provides a pathway for many contaminants to enter the marine food web via the seagrasses. The coastal location of seagrass beds causes them to be especially susceptible to anthropogenic pollution, including accumulation of heavy metals, which has been shown to have many adverse health effects in the seagrasses and marine organisms that feed on them. This study assessed the heavy metal concentrations of seagrasses in three regional locations in South Florida: Port of Miami, Card Sound Aquatic Preserve, and Florida Bay. Three species of seagrasses, Thalassia testudinum, Halodule wrightii, and Syringodium filiforme, which comprise the majority of South Florida seagrass beds, were collected monthly for a period of one year and analyzed for ten heavy metals: (arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), selenium (Se), zinc (Zn)). Concentrations were compared across locations, season, species, and plant part (leaves, shoots, roots, and rhizomes). Concentration ranges, in µg/g (ppm), found in seagrass tissues for all included locations, species, and plant parts were: As (0.02-2.95), Cd (0.09-10.72), Cu (0.38-33.68), Fe (1.52-1877.43), Pb (0.78-156.20), Mn (0.79-300.15), Hg (0.03-16.46), Ni (0.67-87.74), Se (0.01-4.79), Zn (1.48-669.44). Statistical analysis showed significant difference in concentrations among locations, season, species, and plant morphology.
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Delony, Daniel. "Proton Coupled Electron Transfer at Heavy Metal Sites." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1546-5.
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Brodd, Patrick. "Long term heavy metal contamination from leakage water sediments." Thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88909.
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McDaniel, Alicia L. "Synthesis and Characterization of Bis-Phosphine Complexes with Transition Metals." TopSCHOLAR®, 2009. http://digitalcommons.wku.edu/theses/110.
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Extractants and extraction methodologies play a vital role in many industrial processes, from the concentration of precious metals from ores to the separation of longlived nuclei from radioactive waste as well as the removal of heavy metals from soils and water for remediation. The vast majority of extractants rely on the use of nitrogen, oxygen, sulfur or selenium as Lewis base donor atoms to form coordination complexes with the metal ions of interest. These extractants often make use of the chelate effect and/or the macrocyclic effect in order to form stable complexes. Some of the best known types of chelate extractants include polyaminopolycarboxylic acids (N and O donors), polyamines (N donors), dithiocarbamate (S donors) and aminopolythias (N and S donors). The most extensively investigated types of macrocycles include crown ethers (O donors), thia crowns (S donors), aza crowns (N donors) and thiacrown ethers (S and O donors).
A conspicuous omission from the list of donor atoms is phosphorus. It is noted that phosphorus has been employed as a backbone atom in the development of extractants, primarily in phosphonates, phosphates and phosphine oxides. The omission of phosphorus is interesting from two points. First, many of the precious and heavy metal ions of interest (Pd2+, Ag+, Pt2+, Pb2+, Cd2+and Hg2+) can be classified as soft Lewis acids, according to Pearson’s HSAB theory. The relative softness of phosphorus as a Lewis base as compared to oxygen and nitrogen indicates that phosphorus would be a very good donor atom toward these soft metal cations. Secondly, chelating agents containing phosphorus donors form stable complexes with transition metal cations in a variety of oxidation states due to their versatile bonding capability. The !-donor characteristics of the phosphine donor coupled with the ability to " accept from filled or partially filled d orbitals of the metal cations result in strong phosphine-metal bonds.
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Tam, Eric Chi Yan. "Synthesis and reactions of β-diketiminato heavy group 14 metal alkoxides and phosphanides." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/42919/.
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Some low-valent, three-coordinated β-diketiminato heavy group 14 metal complexes have been synthesised and their reactions examined. Initially, our attention is focused on several β-diketiminatolead(II) alkoxides. The lead(II) alkoxides show different basic and nucleophilic reactivities from transition metal analogues. For example, the reaction between the lead(II) tert-butoxide and methyl iodide proceeds only under forcing conditions to give the lead(II) iodide and methyl tert-butyl ether. However, facile reversible carbon dioxide insertion into the lead-oxygen bond is observed. To investigate the steric effect of the bulky β-diketiminato ligand, compounds with various aromatic groups attached to nitrogen have been made. When either [(BDIPh)PbCl] (BDIPh = [HC{C(Me)N(C6H5)}2]−) or [(BDIIPP)PbCl] (BDIIPP = [HC{C(Me)N(4-iPrC6H4)}2]−) was treated with potassium tert-butoxide, the reactions gave the unexpected bis[β-diketiminato]lead(II) complexes. However, treatment of [(BDIDMP)PbCl] (BDIDMP = [HC{C(Me)N(2,6-Me2C6H3)}2]−) with AgOTf led to the expected β-diketiminatolead(II) triflate. These results suggest that the ortho-substituent on the N-aryl groups in the β-diketiminato ligand plays an important role in influencing the formation of bis[β-diketiminato]lead(II) complexes. A series of β-diketiminato heavy group 14 metal phosphanides was synthesised. The phosphorus is pyramidally coordinated in the compounds containing diphenyl- or dicyclohexylphosphanido ligands. In contrast, the geometry at phosphorus is planar in the germanium(II) and tin(II) bis(trimethylsilyl)phosphanides. The phosphorus in the lead(II) bis(trimethylsilyl)phosphanide is pyramidally coordinated. The observed conformations may be explained by the steric congestion from the β-diketiminato ligand and electronic effects in the phosphanido ligand. Reactions of the phosphanido complexes with one equivalent of elemental chalcogen give phosphinochalcogenoito complexes. Further reaction with elemental chalcogen gives phosphinodichalcogenoato complexes. In contrast, treatment of the germanium(II) dicyclohexylphosphanide with elemental chalcogen leads to the formation of germanium(IV) chalcogenide. The presence of NMR-active nuclei in these complexes makes possible detailed spectroscopic analysis.
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Yue, Wei. "Electrochemical Characterization of Metal Catalyst Free Carbon Nanotube Electrode and Its Application on Heavy Metal Detection." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1414750596.
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Verbickas, Rolandas. "Investigation of heavy metal determination using electroanalytical stripping analysis." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140123_101755-89330.
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In this work the gallium and bismuth film plating in situ and ex situ processes were investigated. The metal film plating conditions for determination of heavy metals in water samples were optimized.
When depositing Bi films on glassy carbon electrode it was found, that the addition of Br-1 changes the BiFE morphology making it more uniform and forming crystalline aggregates. The reoxidation peak of Bi was shifted to more negative potentials showing the electrocatalytic effect of bromide for the bismuth film. The addition of the other metal ions to the deposition solutions caused changes in the morphology of the Bi film It has been shown, that Cd was slowing the Bi film deposition and Pb was catalyzing this deposition. Zn(II), Cd(II), Cu(II) and Pb(II) ions were determined in the water samples using bismuth film electrode. The linear calibration curve of each metal was obtained. Good linear responses of the peak area vs. concentration were obtained for Zn(II), Cd(II), Pb(II) and Cu (II) with correlation coefficients of 0.997, 0.997, 0.999 and 0.998 respectively.
The possibilities of gallium film plating were studied. The glassy carbon substrate was chosen for optimization. The optimized deposition conditions were: supporting electrolyte 0.1 M acetate buffer, deposition potential -1.7 V, deposition time 120 s, deposition temperature 40oC. The gallium influence on Pb(II) and Cd(II) deposition at the glassy carbon electrode was studied. It has been shown that Pb(II) and Cd(II)... [to full text]Šiame darbe tiriama galio ir bismuto plėvelinių elektrodų formavimo in situ ir ex situ metodais ypatumai skirtingose sistemose. Optimizuotos bismuto ir galio plėvelinių elektrodų panaudojimo sąlygos sunkiųjų metalų koncentracijos nustatymui. Atliekant bismuto plėvelės nusodinimą ant stikliškosios anglies elektrodo nustatyta, kad papildomas Br- pridėjimas į tiriamąjį tirpalą keičia bismuto plėvelės morfologines savybes ir formuojasi tolygesnė bismuto plėvelė sudarydama kristalines struktūras. Reoksidacinė bismuto smailė pasislenka į neigiamesnių potencialo verčių pusę, kas rodo elektrokatalizinį Br- efektą bismuto plėvelės formavimuisi. Nustatyta, kad Cd(II) pridėjimas į tiriamąjį tirpalą lemia lėtesnį bismuto plėvelės nusodinimą, o Pb(II) pridėjimas katalizuoja bismuto plėvelės nusodinimą. Taip pat nustatyta, kad Pb(II) katalizuoja ir kitų metalų jonų nusodinimą. Bismuto plėvelinis elektrodas sėkmingai pritaikytas sunkiųjų metalų Cu(II), Zn(II), Pb(II), Cd(II) koncentracijos nustatymui pramoniniuose vandens mėginiuose. Gautos Zn(II), Cd(II), Cu(II) ir Pb(II) kalibravimo kreivės, kurių korealiacijos koeficientai atitinkamai yra 0,997, 0,997, 0,999 ir 0,998. Optimizuotos galio plėvelės nusodinimo sąlygos ant stikliškosios anglies elektrodo. Geriausi rezultatai gauti atliekant galio plėvelės nusodinimą 0,1 M acetatiniame buferyje (pH = 4,5) 40o C temperatūroje. Optimizuotas nusodinimo laikas ir potencialas atitinkamai yra 120 s ir -1,7 V. Tiriant galio jonų įtaką Pb(II) ir... [toliau žr. visą tekstą]
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Ho, Ching-yee Christina. "The biomonitoring of heavy metal pollution in the wood and leaf chemistry of urban trees in Hong Kong." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21089978.
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Peterson, Charles Campbell. "Accurate Energetics Across the Periodic Table Via Quantum Chemistry." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822822/.
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Greater understanding and accurate predictions of structural, thermochemical, and spectroscopic properties of chemical compounds is critical for the advancements of not only basic science, but also in applications needed for the growth and health of the U.S. economy. This dissertation includes new ab initio composite approaches to predict accurate energetics of lanthanide-containing compounds including relativistic effects, and optimization of parameters for semi-empirical methods for transition metals. Studies of properties and energetics of chemical compounds through various computational methods are also the focus of this research, including the C-O bond cleavage of dimethyl ether by transition metal ions, the study of thermochemical and structural properties of small silicon containing compounds with the Multi-Reference correlation consistent Composite Approach, the development of a composite method for heavy element systems, spectroscopic of compounds containing noble gases and metals (ArxZn and ArxAg+ where x = 1, 2), and the effects due to Basis Set Superposition Error (BSSE) on these van der Waals complexes.
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Lai, Wei. "Heavy Metal Complexes of Mixed S,N Donor Ligands: X-Ray Crystallography and Solution-State 1H NMR." W&M ScholarWorks, 2005. https://scholarworks.wm.edu/etd/1539626840.
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De, Jesus Jenny Padua. "HEAVY METAL DETECTION IN AQUEOUS ENVIRONMENTS USING SURFACE ENHANCED RAMAN SPECTROSCOPY (SERS)." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1513185193940902.
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Bhandari, Narayan. "Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation." Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/225174.
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ChemistryPh.D.
Anthropogenic activities and natural processes over time have led to the release of toxic heavy metal contaminants into the environment. As a consequence, there is an increasing number of illnesses caused by the exposure of humans to heavy metals and metalloids. The dissertation work presented here focused on the synthesis, characterization, and understanding of the surface chemistry, as well as the photo-reactivity, of a variety of iron (oxyhydr)oxide nano-materials that have relevance for the remediation of heavy metal contaminants, such as arsenic and chromium in aqueous environments. The research focused on the photo-induced reductive dissolution of a nano-dimensioned iron oxyhydroxide, ferrihydrite, in the presence of oxalate, the photo-induced arsenite oxidation, and the simultaneous redox transformation of arsenite and chromate in the presence of ferrihydrite and another environmentally relevant iron oxyhydroxide, goethite. The photo-reductive dissolution of ferrihydrite (using simulated solar radiation) in the presence of oxalic acid was investigated with surface sensitive in situ and ex situ techniques that included attenuated total reflectance Fourier transform infrared spectroscopy. Ferrihydrite at a solution pH of 4.5 exhibited an induction period where the rate of Fe(II) release was limited by a low concentration of adsorbed oxalate due to the site-blocking of carbonate that was intrinsic to the surface of the ferrihydrite starting material. The photo-induced decarboxylation of adsorbed oxalate also ultimately led to the appearance of carbonate reaction product (distinct from carbonate intrinsic to the starting material) on the surface. Ferrihydrite that was prepared under carbonate free condition showed a rapid release of Fe(II) upon irradiation and no induction period was observed. Arsenite [As(III)] oxidation in the presence of ferrihydrite and goethite was also investigated. Ferrihydrite or goethite when exposed to As(III) in the dark led to no change in the oxidation state of As(III) reactant. However, exposure of As(III) in the presence of ferrihydrite or goethite to simulated solar light resulted in the oxidation of As(III) and a reduction of surface Fe(III) leading to an overall increase in the total As removal. At a solution pH of 5, this conversion of As(III) to As(V) on ferrihydrite resulted in the partitioning of a stoichiometric amount of Fe(II) into the aqueous phase and the majority of the As(V) product remained bound to the ferrihydrite surface. In contrast, the As(III)/goethite system showed a different photochemical behavior in the absence or presence of dissolved oxygen. Under oxic conditions, in contrast to ferrihydrite, the majority of the As(V) product was in the aqueous phase and the relative amount of aqueous Fe(II) was significantly less than in the ferrihydrite circumstance. Experimental observations suggested that in the oxic environment, Fe(II) on the goethite surface was heterogeneously oxidized to Fe(III) by dissolved oxygen resulting in the formation of reactive oxygen species that led to the further oxidation of As(III) in solution. Similarly, various experimental investigations were conducted to test the simultaneous removal of As(III) and Cr(VI) from solution. Our results suggested that a surface mediated spontaneous electron transfer between As(III) and Cr(VI) occurred in the presence of Fe- and Al-(oxy)hydroxides. Both infrared and x-ray absorption spectroscopies were conducted to get more insight into the charge transfer reaction and mechanism of electron transfer reaction. In summary, the research discussed here should help to understand the details of oxidation/reduction reactions occurring at mineral-water interfaces. Perhaps more importantly, the methodologies discussed in this dissertation could potentially be novel and eco-friendly approaches for arsenite as well as hexavalent chromium remediation.
Temple University--Theses
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O'Brien, Anna Yosick. "Advances in the design of heavy alkaline earth metal complexes as precursors for chemical vapor deposition." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.
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Pei, Xing. "Copper-based Point-of-care Sensor for Heavy Metal Determination in Public Health." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309640.
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Ho, Ching-yee Christina, and 何靜宜. "The biomonitoring of heavy metal pollution in the wood and leaf chemistry of urban trees in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B43893958.
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Ilsley, Richard. "Development of X-ray absorption fine structure techniques for the study of reactions of heavy metal complexes in solution." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/374678/.
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Extended X-ray absorption fine structure spectroscopy (EXAFS) has been used to characterise polyoxometalate (POM) species and study their reactions on the minute time-scale. Lindqvist-type tungstates have been characterised using quick extended X-ray absorption fine structure spectroscopy (QEXAFS). Differentiation between [LMW5O18]3- species with different heterometals has been demonstrated. The formation of [W6O19]2- and [(Ph2PO2)(ZrW5O18)2]6- have been studied. Intermediates in the formation reaction for [W6O19]2- may include a cluster with 3 tungsten atoms and a cluster with 5 tungsten atoms. Keggin-type molybdates have also been characterised using QEXAFS. EXAFS data has been collected up to 20.7 Å-1 and distances of 6.2 Å have been resolved. Differentiation between different capped [PMo12O40(MX)2]n- species, where the capping species is bound to the core [PMo12O40]3- by 4 bridging oxygen atoms, and reduced [PMo12O40]n- species has been demonstrated. The Mo···Mo distances in reduced POMs are longer than in unreduced POMs. Addition of metal ions to electron-rich Keggin-type POMs by reductive aggregation has been studied and shifting peaks in Fourier transform spectra show the formation of clusters around the metal ions. [Cu(dmp)2][PF6] was studied using X-ray absorption near edge spectroscopy (XANES), X-ray absorption fine structure spectroscopy (XAFS), resonant inelastic X-ray spectroscopy (RIXS) and X-ray emission spectroscopy (XES). Distances of 4.4 Å have been resolved using XAFS spectroscopy. RIXS has been used to demonstrate the 4 eV difference between the Kα peaks for CuI and CuII. The CuII state was generated electrochemically and differentiation between CuI and CuII has been possible using Kα XES.
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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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Nussle, Sean Brian. "TRICHOPTERAN LARVAE AS BIOMONITORS OF TRACE AND HEAVY METAL CONTAMINATION IN NORTHEAST OHIO URBAN STREAMS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1534960377604447.
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Regmi, Suresh Chandra. "Monitoring Metal Containing Particulates Distribution on a College Campus Using Dandelion (Taraxacum officinale) Leaves as Receptors." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1976.
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This study aims to determine the distribution of particulates carrying heavy metals at selected sites on a college campus using dandelion leaves as collectors. As a comparison, sites far away from the campus surrounding Bristol Motor Speedway Car Racing Stadium were also monitored. To reduce the probability of memory effects from the long-term atmospheric deposition or absorption of metals from soil a seasonal plant, dandelion, was used to monitor the metal contents. The metals monitored are cadmium, calcium, copper, chromium, iron, lead, and zinc. Fourteen sites were monitored and samples were collected once a week initially (growing time of the plant), and later at 4-week interval from 28th March to 31st August of 2007. The metal contents of the nitric acid digested and appropriately diluted samples were determined by flame atomic absorption spectrometry using the regular standard calibration curve and also the standard addition method. From the results obtained, and the careful log of the weather and human activities at the different sites, it is concluded that human activities played a major role in the distribution of metal-laden particulates. Also dandelion leaves were proven to be viable collectors of these particulates without memory effects and as indicators of current particulates generated rather than a long-term cumulative one.
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Xiong, Xianzhe, and mikewood@deakin edu au. "Heavy metal accumulation in soils at three field sites subject to effluent irrigation." Deakin University. School of Ecology and Environment, 2003. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20050902.110403.
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Three field sites were chosen to study the environmental assimilative capacity of heavy metals in soil. These sites were the Werribee Farm and the Myome Farm in Australia and Shenyang Zhangshi Irrigation Area in China. The Werribee Farm and the Shenyang Zhangshi Irrigation Area received sewage treatment and application on land for a long time. The Myome farm is an experimental site in which investigations on land application of municipal wastewater on water repellent soils is currently being trailed.
Heavy metal contamination, in particular Cr, Cu and Zn, in the Land Filtration soil of Werribee Farm was widespread. More than a century of sewage irrigation has occurred in the Werribee Farm. The temporal distribution pattern of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the soil at this site follow an exponential trend with time and the spatial distribution pattern of accumulation of heavy metals in different paddocks correlates with the number of years of sewage irrigation at that site in the Farm.
Extensive sewage irrigation at Shenyang Zhangshi Irrigation Area resulted in significant Cd pollution in soil-plant (rice) system and poses a significant threat to the health of local people. Even after eight years since cessation of sewage irrigation, the bioavailable fractions of Cd in the soil as analyzed by sequential extraction techniques were very high thus illustrating long-term persistence.
The simultaneous competitive adsorption of metals in water repellent soils (at Myome Farm in South Australia) was studied. In the competitive situation, Cr, Pb and Cu are the heavy metal cations more strongly adsorbed by the soil, whereas Cd, Ni and Zn are the least adsorbed. The increase in Freundlich adsorption capacity by clay amendment suggested that clayed soils are capable sorption of higher heavy metal loadings compared to the non-clayed water repellent soil, which is more vulnerable to heavy metal inputs.
A simple model of environmental assimilative capacity is proposed. The results of comparison of the three field sites shows that the Werribee Farm has a higher environmental assimilative capacity of heavy metals in soil than the soils at Shenyang Zhangshi Irrigation Area and Myome Farm, however heavy metal contamination at Werribee Farm is still a concern. The model of environmental assimilative capacity of heavy metals in soil is an effective tool to assist management of effluent applied land irrigation systems and can be used to better design environmental engineering systems.
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Powers, Leigh Gayle. "Practical applications of plasmids : overexpression of a bacterial alkaline phosphatase as a mechanism for heavy metal and radionuclide sequestration." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25306.
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Feder, Marnie Jean. "Towards a rational design for sustainable urban drainage systems : understanding (bio)geochemical mechanisms for enhanced heavy metal immobilization in filters." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5570/.
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Sustainable urban Drainage Systems (SuDS) have become an important approach for protection of natural watercourses from non-point sources of pollution. In particular, filtration based SuDS build on the concept of simple, low-cost technology that has been utilized in water treatment for over a century. While it is widely studied and acknowledged that filtration of polluted water through granular material is extremely effective, the inherent geochemical and biogeochemical mechanisms are complex and difficult to ascertain. This is especially true for SuDS filter drains as they have been less well studied. Therefore, this thesis set out to quantify heavy metal removal in gravel filter drains and investigate (bio)geochemical mechanisms responsible for metal immobilization. Determining specific mechanisms responsible for pollutant removal within SuDS provides data that can be used to enhance SuDS design and performance. First, the impact of engineered iron-oxide coatings on heavy metal removal rates were investigated. It was determined that unamended microgabbro gravel immobilized similar quantities of heavy metals to the engineered iron oxide coated gravel. Consequently, engineered iron-oxide coatings were not recommended for future research or use in SuDS systems. Analysis of the surface of microgabbro gravel revealed the surface minerals are weathering to clays, enhancing the gravels affinity for heavy metals naturally. Comparison of microgabbro with other lithologies demonstrated microgabbro displayed enhanced removal by 3-80%. Comparison of microgabbro gravels with and without weathered surfaces demonstrated the weathered surface enhanced metal removal by 20%. From this, it is recommended weathered microgabbro gravel be used in filtration based SuDS where immobilization of incoming heavy metals typical in surface water runoff is important. Following this, the contribution to metal immobilization due to biofilm growth in a gravel filter was examined. Through heavy metal breakthrough curves obtained from experimental flow cells with and without biofilm growth, it was determined that biofilm enhances heavy metal removal between 8-29%. Breakthrough curves were modelled with an advection diffusion equation. The model demonstrated heavy metal removal mechanisms within the column could be described effectively by a permanent loss term. Further, the typical microbial community found within biofilms collected from an urban filter drain was determined to be composed of over 70% cyanobacteria. However, when inoculated into two different lithologies of gravel, the biofilm community composition changed and was influenced by gravel lithology. Dolomite gravel retained 47% cyanobacteria dominance while microgabbro demonstrated 54% proteobacteria dominance. Despite variations in biofilm composition, heavy metal removal capacity and mechanisms were broadly similar between different biofilm types. An additional approach to determine effects of biofilm growth on porosity and flow patterns through a horizontal gravel flow cell was assessed with non-invasive magnetic resonance imaging (MRI). While a copper (Cu) tracer could be imaged within the gravel flow cell, the transport pathways were too complicated to model as the Cu does not follow a plug flow. Processing of 3D high resolution images determined the porosity of the gravel filter to be between 32-34%, in line with literature values for coarse grained dolomite gravel. Further post-processing allowed for localized biofouling to be analyzed. Highest concentration of biofilm growth in columns resulted from longer growth periods and exposure to light. Moreover, biofilms tended to grow closer to the inlet which typically offers a higher nutrient dose and in pore space regions close to the light source (both of which would be representative of the surface of a filter drain). Thus, MRI analysis of biofouling has important implications for filter drain design and efficiency through assessment of pore space blockage. Finally, the possibility of enhancing heavy metal removal in sand (another filter material common in SuDS) with nano zero-valent iron (nZVI) particles was considered. Metal breakthrough curves for column experiments indicate that use of 10% nZVI enhanced sand improved metal immobilization between 12-30% and successfully removed > 98% Cu and Pb. It is therefore believed that nZVI enhanced sand is a promising avenue of future research for areas prone to high heavy metal loads.
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Svengren, Henrik. "A Study of the Environmental Conditions in Lake Nakuru, Kenya, Using Isotope Dating and Heavy Metal Analysis of Sediments." Thesis, Stockholm University, Stockholm University, Department of Physical, Inorganic and Structural Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-40909.
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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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Morgan, Judith. "Part I: Oxidation of Heavy Metal Sulfides in Relation to the Environment; Part II: Fundamental Theory & Experiments Concerning Gas Chromatography & Mass Spectrometry." TopSCHOLAR®, 1990. https://digitalcommons.wku.edu/theses/2672.
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Oxidation of heavy metal sulfides is a thermodynamically spontaneous process. Because of this, metal sulfides in the presence of oxygen are not stable. Currently there are over 100 streams and rivers, within the U.S., contaminated with heavy metal mine drainage; therefore an approved method of restoration is necessary. Precipitation of heavy metals as sulfides using H2S as a reductant has been favorably reviewed as a restorative technique to clean up mining areas. However, using this technique on the laboratory scale does not prove to be a viable answer and shows strong pH dependence.
In the past three years the ILI (Instrumentation and Laboratory Improvement) has awarded funding to over 50 institutions, in the U.S., for the purchase of GC/MS. Therefore, there is a great need for laboratory experiments to properly train students in this field in American universities. A strong theoretical treatment for sophomore-level students is presented within this thesis and from this, three experiments have been developed in order to educate young professionals seeking a career in the field of chemistry.
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Budkina, Darya S. "Ultrafast photophysical and photochemical dynamics of polyhalogenated alkanes, cycloalkanes, and transition metal complexes." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1553686775405944.
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Akgun, Aydin Mert. "Sorption Of Cadmium And Lead On Activated Carbons Produced From Resins And Agricultural Wastes." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606713/index.pdf.
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In this work, adsorption of cadmium and lead from waste solutions by activated carbon was investigated. The activated carbons were produced from ion exchange resins and agricultural wastes in previous thesis studies under different conditions.
BET surface areas of the activated carbons were given in previous studies. They were further characterized in this study. Slurry pH was measured by change in pH of water in which activated carbon was added. Methylene blue numbers were determined by adsorption of methylene blue onto activated carbons. Isoelectric points were determined by measuring zeta potential of activated carbons at different equilibrium pH.
Results of the first part of sorption experiments showed a strong dependency of adsorption on pH since adsorption mechanism was exchange of heavy metal ions with H+ ions on the surface. Activated carbon produced from hazelnut shell had the highest removal efficiency with 95% Pb removal and 50% Cd removal at pH 6. However, activated carbon produced from apricot stone removed only 25% and 80% of Cd and Pb, respectively at the same pH.
Initial concentration had positive effect on percent removal as shown by the second part of sorption experiments. This can be explained with saturation of available active sites as initial concentration increased. Activated carbon produced from hazelnut shell could remove 42% of Cd and 85% of Pb, but the one produced from synthetic resin couldn’
t remove Cd and Pb more than 20% and 35%, respectively at initial concentration of 100 mg/l. Langmuir and Freundlich isotherms were plotted and both isotherms were in good agreement with experimental data.
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Kiriarachchi, Hiran D. "Nanostructured Materials for Photocatalysis, Water Treatment and Solar Desalination." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5886.
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Maintaining a constant supply of clean drinking water is among the most pressing global challenges in our time. About one-third of the population is affected by the water scarcity and it can only get worse with climate change, rapid industrialization, and the population growth. Even though nearly 70 percent of the planet is covered by water, the consumable freshwater content is only 2.5 percent of it. Unfortunately, the accessible portion of it is only 1 percent. Even so, most of the freshwater bodies are choked with pollution. Considering the vast availability of saline water on the planet and the increasing wastewater generation, seawater desalination, and wastewater treatment and recycling seem to have the potential to address current water-related issues. Therefore, it is necessary to find efficient techniques for seawater desalination and wastewater treatment. The use of nanostructured materials for these applications is becoming a popular approach due to the unique chemical and physical properties they possess compared to bulk materials
Solar energy is the cleanest and most abundant renewable natural resource available. Materials for solar photothermal energy conversion are highly sought after for their cost savings, clean environment, and broad utility in providing water heating and/or steam for many applications including domestic water heating and solar-driven desalination. Extensive research efforts have been made to develop efficient solar absorbers with characteristics such as low weight, low thermal conductivity, broad solar absorption and porosity to be able to float on water to provide more efficient and cost-effective solar steam generation systems. Metal NPs have been proposed to take advantage of the high efficiency of the photothermal energy conversion associated with surface plasmon resonance absorption. Nanostructured carbon-based materials such as graphene oxide, carbon nanotubes, carbonized biomass are also in use due to their excellent photothermal energy conversion ability over the range of the visible and near infra-red region of the electromagnetic spectrum.
In this dissertation, five projects based on the utility of nanostructured materials for desalination, photocatalysis and water treatment will be discussed. The first three projects involve the fabrication and design of plasmonic and carbon-based photothermal materials for applications in solar steam generation, water desalination, and wastewater treatment. In the fourth project, a unique shape of ZnO nanostructure was synthesized for photodegradation of organic dyes in industrial wastewater. The final project demonstrates the shape-controlled synthesis of iron carbide nanostructures and composite materials of aminated graphene oxide for the removal of Cr(VI) from wastewater.
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Schweitzer, Na'ama. "Greening the Streets: A Comparison of Sustainable Stormwater Management in Portland, Oregon and Los Angeles, California." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/pomona_theses/85.
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Stormwater runoff is one of the main sources of pollution for urban waterways. Stormwater has traditionally been managed through concrete-based storm drainage systems, but the past twenty years have introduced an alternative in the form of green infrastructure. Green infrastructure for stormwater management involves the use of low impact development (LID), often vegetated facilities to mimic natural hydrologic systems that capture and allow infiltration of rainwater where it falls and from impervious surfaces upstream, before entering the drainage system. Portland, Oregon and Los Angeles, California have adopted green infrastructure into their stormwater management plans. For this project, bioswales, a form of vegetated LID facility, were tested in each city to determine their pollutant retention capabilities. Results from Portland show that bioswales filter out heavy metals effectively, and results from Los Angeles show that bioswales accumulate heavy metals in the soil over the course of the year (also due to filtering out metals from the stormwater). These results raise the question of whether accumulation can reach dangerous levels or saturate the soil with pollutants so that removal efficiency is diminished, indicating a need for further monitoring. However, the success of bioswales up to this point is encouraging and indicates that this method should continue to be employed.
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Moreira, Cindy Silva. "Adsorção competitiva de cádmio, cobre, níquel e zinco em solos." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-11112004-144415/.
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Dentre os processos envolvidos no comportamento e biodisponiblidade dos metais pesados nos solos, aqueles relacionados com a adsorção são de grande importância. Tendo em vista a natureza multielementar do sistema solo-solução e a complexidade das reações envolvidas, o conhecimento dos mecanismos de adsorção em sistemas competitivos permite uma avaliação mais realista do comportamento dos metais no solo. Os objetivos desse trabalho foram (i) avaliar a adsorção competitiva de cádmio, cobre, níquel e zinco, tomadas da camada mais superficial (horizonte A) de 14 solos representativos dos do Estado de São Paulo; (ii) obter isotermas de adsorção em sistemas competitivo e não-competitivo, utilizando a equação matemática de Langmuir para simular a adsorção; (iii) estabelecer seqüências de afinidade metálica para cada solo e (iv) estabelecer a relação entre o comportamento adsortivo dos metais e alguns atributos dos solos, mediante estudos de correlações simples e regressões múltiplas. Ao correspondente a 2,0 g de terra foram adicionados 20 mL de solução 0,01 mol L-1 de NaNO3 (relação 1:10) contendo concentrações equimolares (0,017; 0,034; 0,085; 0,17; 0,255; 0,51; 0,85 e 1,275 mmol L-1) de Cu, Ni, Cd e Zn, na forma isolada (sistema não competitivo) e em conjunto (sistema competitivo). O conjunto foi agitado por 1 h e, em seguida, as amostras foram centrifugadas a 1.100 rpm durante 10 minutos e filtradas. As concentrações dos metais em solução foram determinadas por espectrofotometria de absorção atômica. A quantidade de metal adsorvida foi estimada pela diferença entre a concentração inicial e a concentração de equilíbrio. O Latossolo Vermelho eutroférrico, o Nitossolo Vermelho eutroférrico, o Argissolo Vermelho-Amarelo (textura argilosa e muito argilosa) e o Chernossolo Argilúvico foram os solos que apresentaram maior capacidade de adsorção dos metais, enquanto que os menores valores de metais adsorvidos foram do Neossolo Quartzarênico e do Argissolo Vermelho-Amarelo (textura arenosa). A competição entre os metais diminuiu, de maneira, a adsorção máxima dos mesmos. A seqüência de afinidade mais comum encontrada no sistema não-competitivo foi Cu > Zn > Ni > Cd. No sistema competitivo, a seqüência mais comum foi Cu > Cd > Zn > Ni. Em geral, o modelo de Langmuir simulou de maneira satisfatória a adsorção dos metais. Os atributos que apresentaram correlação positiva com a adsorção máxima dos metais foram pH, MnO, CTC efetiva e silte. A correlação foi negativa com os teores de areia dos solos. Na regressão múltipla, as adsorções máximas de Zn, Cd e Ni estiveram relacionadas a CTC efetiva e com MnO. Para o Cu, somente o conteúdo de MnO relacionou-se com a adsorção máxima. Tais resultados reforçam a importância desse óxido no comportamento de metais pesados em solos de regiões tropicais úmidas.Among the processes involved in the behavior and the bioavailabilty of heavy metals in soil, those related with the adsorption are of great importance. Despite of the multielementary nature of the soil-solution system and the complexity of the involved reactions, the knowledge of the adsorption mechanisms in competitive systems allows a more realistic evaluation of the metals behavior in the soil. The objectives of this work was (i) to evaluate the competitive adsorption of cadmium, copper, nickel and zinc in surface samples (A horizons) of 14 representative soils of the State of São Paulo, Brazil; (ii) to obtain adsorption isotherms in competitive and non-competitive systems, using the Langmuir model in order to simulate the adsorption; (iii) to establish metal affinity sequences for each soil and (iv) to establish relationships between the adsorptive behavior of metals and some soils attributes using simple correlations and multiple regressions analysis. Two grams soil subsamples were set into 50 mL centrifuge tubes, adding 20 mL of 0.01 mol L-1 NaNO3 solution (relation 1:10) at equimolar concentrations (0.017; 0.034; 0.085; 0.17; 0.255; 0.51; 0.85 and 1.275 mmol L-1) of Cu, Ni, Cd and Zn, in the isolated form (non-competitive system) and in set (competitive system). The obtained suspensions were shaked during one hour, centrifuged afterwards (1,100 rpm) through 10 min and filtered. The metals concentrations in solution were determined by atomic absorption spectrophotometry. The adsorbed metal amounts were assumed to be equal to the difference between the initial amount and the metal remaining content at the ending of the reaction period. The Rhodic Eutrudox, Kandiudalf Eutrudalf, Typic Hapludult-2 (clayey-textured), Typic Hapludult (clayeytextured) and Typic Haplaquoll presented the highest metals adsorption capacity, whereas the lowest was observed for Typic Quartzipsamment and for Arenic Hapludult. In general, the competition between metals diminished their maximum adsorption. In the non-competitive system, the most common affinity sequence was Cu > Zn > Ni > Cd, whereas in the competitive system, the most common sequence was Cu > Cd > Zn > Ni. In general, the Langmuir model simulate satisfactorily the adsorption of metals of the studied soils. The soils attributes presenting positive correlation with the maximum adsorption of metals were pH, MnO, CTC and silt. The correlation was negative with the soil sand content. Employing the multiple regression, the maximum adsorption of Zn, Cd and Ni was found to be related with CTC and MnO, while for Cu only the MnO content was related with it maximum adsorption. Such results pointed out the importance of the manganese interactions as a controlling factor related to the behavior of heavy metals in soils from tropical humid areas.
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MacIver, Vicki. "Soil chemistry of heavy metals under contrasting vegetation covers." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/5688/.
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The site of study (Pollok Park, Glasgow) features soil under both a coniferous canopy (predominantly Corsican Pine) and a deciduous canopy (predominantly Beech). There is a clear segregation between the two vegetation types which enables a direct comparison into the contribution of canopy type to the heavy metal distribution in soil. Average total metal contents of cores extracted from the two soil types indicated that the deciduous cores have a greater total content of Cr, Cu, Fe, and Mn, and that the two core types contain approximately the same Pb and Zn content. Concentration profiles for Cr, Cu, Fe, Mn, Pb and Zn were established for the two soil types. They showed enrichment of Cr, Cu, Pb and Zn at the surface. Correlation graphs [LOI vs. metal (Cr, Cu, Pb and Zn)] showed there to be a correlation between organic matter content and concentrations of these metals. Molar ratios (carbon : metal [Cr, Cu, Pb and Zn]) were estimated from the correlation graphs. In each case, these were found to be of considerable value, indicating that perhaps these metals are complexed by large organic molecules. Mn and Fe showed no enrichment to the surface and no correlation with organic matter. Speciation studies (Modified BCR sequential extraction procedure and cupric ISE investigations) were conducted on the surface soil (top 5cm), litter and leaves taken from below both vegetation types (deciduous and coniferous) in order to gain an understanding of soil-metal associations. The deciduous and coniferous soils were found to have virtually identical fractionation patterns of Cr, Cu, Pb and Zn (Modified BCR sequential extraction).
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wickramaratne, nilantha P. "Phenolic Resin-Based Porous Carbons for Adsorption and Energy Storage Applications." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1416224723.
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Hao, Jicheng. "An investigation of the inorganic chemistry of peat systems." Thesis, Liverpool John Moores University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337789.
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Reis, Tadeu Cavalcante. "Distribuição e biodisponibilidade do níquel aplicado ao solo como NiCl2 e Biossólido." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-03092003-160423/.
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O comportamento do Ni no solo, principalmente quando adicionado através de biossólidos, ainda é pouco conhecido. Este trabalho objetivou avaliar a influência dos teores totais do metal, de matéria orgânica e dos valores de pH na distribuição daquele elemento no solo e na sua biodisponibilidade. Foram conduzidos três experimentos de incubação em vasos mantidos em casa de vegetação, utilizando 3 kg de amostras da camada de 0 - 0,20 m de dois solos: ARGISSOLO VERMELHO AMARELO Distrófico (PVAd) e NITOSSOLO VERMELHO Distrófico Latossólico (NVdl). Dois experimentos foram montados em solos diferentes, em esquema fatorial 2x2x3, nos quais 2 doses de Ni (21 e 42 Kg ha 1 ) como NiCl2, foram incubadas durante 120 dias, sob dois teores de matéria orgânica e dois valores de pH, obtidos pela adição de turfa e de calcário, respectivamente. Num terceiro experimento fatorial (2x4), os mesmos dois solos foram incubados por 150 dias com a dose de 150 Mg ha -1 de quatro diferentes biossólidos. Posteriormente, cultivou-se alface em todos os vasos por 50 dias Após a incubação, amostras de solo foram analisadas quimicamente, inclusive efetuando-se extrações seqüenciais para determinar a distribuição do Ni adicionado através de NiCl2 e de biossólido. Foram consideradas as frações do metal solúvel + trocável, carbonatos, matéria orgânica, óxidos e residual. Realizou-se também a especiação do Ni baseada no equilíbrio de Donnan, no extrato de saturação das amostras, para discriminar a porção do Ni solúvel que se achava na forma de íon livre. O calcário foi o fator que mais afetou o comportamento do metal, reduzindo a concentração na fração trocável e aumentando-a nas frações matéria orgânica e óxidos. A turfa aumentou os teores do metal na fração trocável e os reduziu nas frações óxidos e matéria orgânica. O NiCl2 aumentou o teor de Ni nas três frações citadas. Os teores do metal nas frações de cada solo foram modelados por equações de regressão, em função dos teores de C-orgânico, Ni total e pH do solo. A distribuição do Ni no solo, quando adicionado através de biossólidos apresentou semelhanças com a distribuição do metal nos próprios biossólidos. Nestes casos, o Ni predominou nas frações mais fortemente retidas, conferindo ao metal comportamento distinto daquele observado pela adição do NiCl2. Tais diferenças puderam ser confirmadas pela ineficiência das equações obtidas nos experimentos com NiCl2, em predizer os teores do metal nas frações dos solos tratados com biossólidos. Na especiação, doses mais elevadas de calcário e turfa resultaram em menores teores de Ni solúvel e livre, os quais aumentaram com a dose de NiCl2. Concentração de ambas as formas de Ni se correlacionaram com os teores do metal absorvidos pelas plantas. Na aplicação de biossólidos ao PVAd, a determinação do Ni livre foi particularmente importante para se prever a biodisponibilidade de Ni para alface. Essencialmente, pode-se concluir que a extração seqüencial e a especiação em extrato de saturação foram eficientes para demonstrar diferenças do comportamento do níquel quando o metal foi aplicado como NiCl2 e como biossólido.The role of Nickel in soils under the application of biossolids is still not very well known. The objectives of this study were to investigate the influence of total Nickel and organic carbon content, and soil pH, in the Nickel distribution among soil fractions and the bioavailability of the metal to lettuce. Three incubation pot trials were carried out in greenhouse placing in each one 3 kg of the 0-20cm layer of soil. Two soils types were considered: Typic Halpludult and Rhodic Kandiudox. In two of the trials, one for each soil type, soil samples were treated with rates of NiCl2, lime and peat as a source of organic matter and incubated during 120 days. In the third pot trial the above mentioned soils were incubated with four different types of biossolids during 150 days. Once the incubation period ended soils samples were collected and lettuce was planted in the pots of all three trials. Soils samples were submitted to a sequential extraction procedure which comprised the following fractions: exchangeable plus soluble; carbonate, organic, oxides and residual. Soil saturation extracts were also obtained for the determination of free Ni +2 concentration using the Donnan equilibrium technique. When NiCl2, peat, and lime were applied to soils, changes in pH due to lime caused exchangeable Ni to decrease and raised Ni content in organic and oxide fractions. Peat promoted an higher Ni content in the exchangeable fraction and reduced it in the oxide and organic fraction. I contrast NiCl2 raised Ni content in all of the above motioned fractions. Nickel content in all soil fractions were modeled by regression equations using total Ni, organic carbon, and pH as independent variables. Data for the Ni distribution in soils fractions under biossolids application were similar to results from sequential extraction in the biossolids in terms of percentage. In the biossolids trial Ni occurred most in residual fraction of soil, which contrasts with results obtained when Ni was supplied as NiCl2. Speciation study showed that higher rates of lime and peat promoted lower levels of soluble and free Ni in the soil solution. The opposite was detected when NiCl2 was applied. Both soluble Ni and free Ni +2 were well correlated with the Ni content in lettuce, when the metal salt was supplied as Ni source. However, free Ni +2 was a better indicator for Ni bioavailability when bissolids were applied in PVAd. In resume it may be concluded that the sequential extraction procedure and the speciation by means of the Donnan equilibrium approach were useful to express the different behavior of nickel in soil when NiCl2 or bissolids were the source of the metal.
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Baronaitė, Sandra. "Vario (II) ir chromo (VI) jonų pašalinimas metaline geležimi iš vandeninių tirpalų." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090629_122147-11310.
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Šiame eksperimente buvo nagrinėjama pH įtaka Cr (VI) ir Cu (II) jonų pašalinimui iš vandeninių tirpalų, naudojant metalinę geležį Fe (0), kai tirpalų pH vertės buvo nuo 2 iki 6, purtymo procese, uždaruose ir atviruose induose. Kadangi Cr (VI) ir Cu (II) jonų koncentracijų sumažėjimas tirpale priklauso nuo geležies paviršiaus, tai labai svarbu ją tinkamai paruošti: išvalyti ir aktyvuoti. Maksimalus Cr (VI) jonų pašalinimo efektyvumas buvo esant pH vertei 2, o Cu (II) jonų atveju, kai pH vertė 4 uždaruose induose ir atviruose induose – chromo atveju pH 6, vario atveju, kai pH 4. Pašalinimo įvertinimui naudojamos kalibraciniės kreivės pagal kurias apskaičiuojamos likusiųjų jonų koncentracijos, matuojant tirpalų optinius tankius. Metodas yra pigus ir patikimas, nes pašalinima didelė dalis sunkiųjų metalų jonų.The effects of pH on Cr (VI) and Cu (II) ions removal from solutions by Fe (0) was investigated by batch shaking process. Since the presence of ferrous iron in the solution is mainly responsible for Cr (VI) and Cu (II) reduction the surface of iron must be purified and activated. The maximum Cr (VI) removal efficiency was found at pH 2 and in Cu (II) case it was pH 4 without oxygen and in case with open jar it was for Cr (vi) removal pH 6 and for Cu (II) removal pH 4. Remained concentrations of Cu (II) and Cr (VI) ions were investigated using calibrated graphs and analysis of optical density. This study confirmed that this method is cheap because we can use wasted iron and effective of removing most of heavy metal ions from solutions.
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Niehus, Christina. "Untersuchungen zur Selektivität unterschiedlich substituierter Iminodiessigsäure-Ionenaustauscher gegenüber zweiwertigen Metallionen." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2007/1319/.
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Zur selektiven Entfernung von Schwermetallen aus industriellen Abwässern und Prozesslösungen der metallverarbeitenden Industrie werden synthetische metallkomplexierende funktionelle Polymere – mit Iminodiessigsäure (IDE) als aktive Spezies – seit Jahren erfolgreich zur Eliminierung störender Kationen eingesetzt. Ständig steigende Anforderungen an die Qualität der aufzubereitenden Wässer verlangen nach leistungsfähigen Selektivaustauschern, die den Erhalt der Eigenschaften von Prozesslösungen (z. B. pH-Wert, Salzgehalt) ermöglichen. Ziel der Untersuchungen war es, die strukturellen Matrixeinflüsse auf Beladung, Kapazität, Selektivität und Kinetik durch Variation der Matrix und der experimentellen Bedingungen näher zu untersuchen. Auf Basis einer monodispersen Erstsubstitution eines Styren-Divinylbenzen-Copolymerisates wurde durch gezielten Einbau funktioneller Gruppen – Synthese mit differenziertem Substitutionsgrad (TK/N 1-2) – versucht, systematisch den Einfluss des Substitutionsgrades der Matrix auf die Eigenschaften der Ionenaustauscher zu analysieren. Methodisch geordnet wurden zunächst die Versuche nach dem Batch- und anschließend nach dem Säulenverfahren durchgeführt und parallel dazu die Matrix charakterisiert. Das Verhalten der funktionellen Ankergruppen in Abhängigkeit vom pH-Wert der Lösung (pH-Bereich 2 - 5) wurde untersucht, der optimale Anreicherungs-pH-Wert, die maximale Beladung (Kapazität) und Selektivität der unterschiedlich substituierten Proben für die Schwermetall-Ionen Cu, Zn, Ni, Cd, Pb und Co ermittelt. Den statischen Versuchen folgten dynamische Untersuchungen im Säulenverfahren. Ziel war die Ermittlung des Durchbruchverhaltens und der Durchbruchkapazität bei optimalem pH-Wert in Abhängigkeit vom Substitutionsgrad gegenüber den Einzelmetallionen (Cu, Ni, Zn) und ausgewählten Paaren (Cu/Ni, Cu/Zn, Ni/Zn). Alle Ionenaustauscher wurden ausschließlich in der Ca-Form eingesetzt.Selective ion exchange offers a good solution for cleaning many waste streams. The aim of this study was to develop selective ion exchange materials for effective and economical applications in waste water treatment. The investigation of chelate resins is based on iminodiacetate with different secondary substitution (degree of substitution TK/N 1 - 2, from aminoacetic acid to iminodiacetate as functional group). As comparison the weak acid resin Lewatit TP 207 was used. The research focused on the application of selective ion exchange resins for waste effluents to ascertain the feasibility of a selective ion exchange process employing chelating cation exchangers for heavy metal removal. The metals of interest were copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), lead (Pb) and cadmium (Cd) and the resins appointed in the Ca-form. The batch operation was conducted to determine the equilibrium data and the operating resin capacity, one of the most important properties. The main equilibrium parameter affecting the ion exchange was the pH value (array 2-5). The best accumulation pH value was obtained using pH 5 for all metals. The only exception was lead with pH 3. After determining the viability of the different resins with batch systems, this study has focused on the column mode experiments. They were generated for the selected resins in the continuous ion exchange process which are essentially reserved for industrial applications. A practical application of the breakthrough curves is the determination of the breakthrough time which helps to find the best operating conditions.
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Guino-o, Marites A. "Placing heavy alkaline earth metals on the map Synthetic access, structure evaluation and reactivity studies of heavy alkaline earth organometallics /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.
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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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Mandadi, Keerthy. "Removal of Heavy Metals Using Modified Limestone Media: Zinc and Cadmium." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1170.
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Heavy metal contamination is a serious concern throughout the world. Increased concentrations in drinking water have many negative impacts on human health. Limestone is an inexpensive and simple media for removing high concentrations of heavy metals from drinking water supplies. Ferric based media is commonly used to remove zinc, cadmium, lead, arsenic and other heavy metals. The drinking water standards set by the US EPA for cadmium, zinc and arsenic are 0.005 mg/L, 5 mg/L and 0.010 mg/L respectively. Bangladesh, parts of India, China and the United States have high concentrations of arsenic in drinking water. Although many technologies exist for heavy metal removal, most of these are complicated and are associated with high costs making them ineffective and unfavorable to be used in impoverished areas.
We propose a novel method that combines the benefits of limestone with the capacity of ferric media in an iron-coated limestone based material. Samples of water with various concentrations of zinc and cadmium were prepared and batch tests were performed using both uncoated and iron coated limestone and are compared in removal efficiency. Kinetics studies showed that zinc is removed to a maximum level after 24 hours, while cadmium takes only 15 minutes. The effect of pH on removal of heavy metals was also studied. Metals are analyzed using Inductively Coupled Plasma Emission Spectroscopy (ICP-ES). Limestone is readily available and is also easy to coat with iron, making this material a cost effective and affordable method to be used by developing countries.