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1
Sekhula, Koena Sinah. "Heavy metal ion resistance and bioremediation capacities of bacterial strains isolated from an Antimony Mine". Thesis, University of Limpopo, 2005. http://hdl.handle.net/10386/139.
Testo completoAbstract (sommario):
Thesis (M.Sc.) -- University of Limpopo, 2005Six aerobic bacterial strains [GM 10(1), GM 10 (2), GM 14, GM 15, GM 16 and GM 17] were isolated from an antimony mine in South Africa. Heavy-metal resistance and biosorptive capacities of the isolates were studied. Three of the isolates (GM 15, GM 16 and GM 17) showed different degrees of resistance to antimony and arsenic oxyanions in TYG media. The most resistant isolate GM 16 showed 90 % resistance, followed by GM 17 showing 60 % resistance and GM 15 was least resistant showing 58 % resistance to 80 mM arsenate (AsO4 3-). GM 15 also showed 90 % resistance whereas isolates GM 16 and GM 17 showed 80 % and 45 % resistance respectively to 20 mM antimonate (SbO4 3-). Arsenite (AsO2 -) was the most toxic oxyanion to all the isolates. Media composition influenced the degrees of resistance of the isolates to some divalent metal ions (Zn2+, Ni2+, Co2+, Cu2+ and Cd2+). Higher resistances were found in MH than in TYG media. All the isolates could tolerate up to 5 mM of the divalent metal ions in MH media, but in TYG media, they could only survive at concentrations below 1 mM. Also, from the toxicity studies, high MICs were observed in MH media than TRIS-buffered mineral salt media. Zn2+ was the most tolerated metal by all the isolates while Co2+ was toxic to the isolates. The biosorptive capacities of the isolates were studied in MH medium containing different concentrations of the metal ions, and the residual metal ions were determined using atomic absorption spectroscopy. GM 16 was effective in the removal of Cu2+ and Cd2+ from the contaminated medium. It was capable of removing 65 % of Cu2+ and 48 % of Cd2+ when the initial concentrations were 100 mg/l, whereas GM 15 was found to be effective in the biosorption of Ni2+ from the aqueous solutions. It was capable of removing 44 % of Ni2+ when the initial concentration was 50 mg/l. GM 17 could only remove 20 % of Cu2+ or Cd2+. These observations indicated that GM 16 could be used for bioremediation of xvi Cu2+ and Cd2+ ions from Cu2+ and Cd2+-contaminated aqueous environment, whereas GM 15 could be used for bioremediation of Ni2+.
National Research Foundation and the University of the North Research Unit
2
Oltmanns, Jan. "Biosensors for heavy metals". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/22854.
Testo completoAbstract (sommario):
Heavy metals from natural and man-made sources can be a great threat to human and animal life. As small inorganic ions they are challenging to detect, usually requiring expensive and complicated machinery. Several heavy metals can accumulate in the human body, leading to long term toxic effects on the nervous system. Many bacteria have developed strategies to survive in heavy metal rich environments. One of these strategies is a bacterial operon containing genes for detoxification mechanisms controlled by a promoter and a regulatory protein. In this work some of these promoter-protein pairs, Pars-ArsR, PcopA-CueR, PmerTPAD-MerR and PzntA-ZntR from Escherichia coli have been employed in the design and construction of a set of biosensors aimed at the detection of heavy metals in drinking water. Biosensors usually employ biological recognition elements, transducing the signal from these to produce an output that can be integrated into electronic circuitry. The sensors presented in this work focus on reducing complexity and on providing a controlled sensor reaction. The arsenic biosensor ‘AsGard’ is based on the Pars-ArsR pair and functions by making the dissociation of an ArsR-mCherry fusion protein from its binding site in the Pars promoter visible. In the cell, ArsR dissociates from Pars upon binding of trivalent arsenic ions. Immobilising the relevant part of the Pars sequence on a solid plastic support allows for the mobilisation of previously bound ArsR-mCherry proteins in the presence of arsenic to become the sensor output. The AsGard sensor detects arsenic within minutes in a concentration range overlapping with the arsenic thresholds for drinking water as set by the World Health Organisation. Additional prototype sensors are presented bringing a reporter gene under the control of the aforementioned promoters. These sensors have been tested in vivo and in vitro in a cell free transcription translation system and partially detect metal concentrations close to relevant ranges. The Pars based sensor is tuneable in vitro by modifying the ratio of the supplied regulatory protein ArsR and is able to detect arsenic well within the relevant range. Spinach2, a fluorescent RNA aptamer, may make future designs independent from translation, drastically reducing complexity of cell free biosensors based on cis-trans transcriptional regulation.
3
Dey, Gopal Ch. "Application of functionalised chelating resins for selective sorption of metal ions with special reference to heavy metals". Thesis, University of North Bengal, 2011. http://hdl.handle.net/123456789/1391.
Testo completo
4
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.
Testo completo
5
Sörme, Louise. "Urban heavy metals stocks and flows /". Linköping : Univ. : Vatten i natur och samhälle, Institutionen för tema [distributör], 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/arts270s.pdf.
Testo completo
6
Beckett, C. L. "Heavy metals in Severn Estuary ecosystems". Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373733.
Testo completo
7
Xu, Yuping. "Interactions of heavy metals with minerals /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487856076412928.
Testo completo
8
Limson, Janice. "Aging, sex, death (and heavy metals)". Rhodes University, 2011. http://hdl.handle.net/10962/d1019732.
Testo completo
9
Wang, Jin 1954. "Extraction of heavy metals with supercritical carbon dioxide : a novel approach to heavy metal analysis and decontamination". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39890.
Testo completoAbstract (sommario):
The technique of extraction with supercritical carbon dioxide (SC-CO$ sb2$), which is now used routinely for the recovery of non-polar analytes from a variety of liquid and semipermeable solid media, was extended to the efficient extraction of metal ions. Measurements of the solubilities in SC-CO$ sb2$ corroborated the hypothesis that the non-polar character of a series of tetraalkylammoniun dialkyldithiocarbamates ion pairs was influenced (i) primarily by the chain length of the alkyl substituent(s) on the carbamate nitrogen and (ii) to a lesser extent, by the chain length of the alkyl substituent(s) on the ammonium counter ion. In operation, analyte metal(s) in aqueous medium was derivatized by in situ complexation with the dithiocarbamate complexing reagent and the product complex(es) was partitioned into the SC-CO$ sb2$ mobile phase then purged from the extractor by replacing the headspace with fresh solvent. A novel silica flame-in-tube interface was developed for the sensitive detection, by atomic absorption spectrometry (AAS), of As, Cd, Cu, Mn, Pb, Se, or Zn in SC-CO$ sb2$ extractor eluate. For different analyte elements, the limits of detection (LODs) ranged from sub-nanogram to low picogram if standard was flow injected into the mobile phase. These sensitivities permitted differences in the rates of mobilization of different forms of the analyte metal from various media to be explored as a technique for probing the interaction of the analyte metal with the matrix. A portion of the Zn burden in fresh bovine liver was mobilized rapidly in the absence of complexing agent and the remainder was solubilized more rapidly than the Zn in a freeze-dried reference material of this tissue. The nebulizer assembly of a conventional flame-AAS was modified to extend the range of metals amenable to on-line detection. Supplemental heating of the inlet air to 200$ sp circ$C resulted in an on line detector which provided approximately a ten-fold improvement over convention
10
Mullins, M. "Subcellular localization of metals in metal tolerant higher plants". Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384378.
Testo completo
11
Cheung, Kai-him Matthew, e 張啟謙. "Bioremediation of toxic metals". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/194562.
Testo completoAbstract (sommario):
Traditional remediation techniques in removing toxic metal contaminants using physical and chemical methods are expensive and may cause other forms of damage to the environment, comparing with these techniques bioremediation can serve as an inexpensive, effective and environmental friendly remediation method. This thesis mainly discusses different bioremediation techniques and identifies possible areas in Hong Kong for bioremediation and suggests bioremediation methods for each potential area. Bioremediation of toxic metals is the use of microorganisms, plants, or even larger sized organisms to decontaminate sites with toxic metals.
Bioremediation includes phytoremediation, microremediation and vermiremediation which use plants, microorganisms and earthworms to remediate contaminated environments respectively. The 4 most common mechanisms in phytoremediation of toxic metals are phytoextraction, phytofiltration, phytovolatilization and phytostabilization. Phytoremediation are used frequently for remediation around the world and its development includes using well-understood technology and genetic engineering to increase its effectiveness. Microremediation is another promising technology in bioremediation of toxic metals and consists of 6 major mechanisms which are biosorption, bioaccumulation, biotransformation, bioleaching, biomineralization and microbially-enhanced chemisorption of metals.
Microremediation is mainly in research phase and its development includes identifying new species, combining with phytoremediation and genetic engineering. Vermiremediation is another rapidly developing technique in bioremediation of toxic metals, assisting other bioremediation by burrowing actions of earthworms and its excretion, and accumulating toxic metals inside their bodies. Vermiremediation is also in research phase but it is rapidly developing. Generally, bioremediation is around 60% cheaper than traditional remediation methods and no pollutants are emitted during the process. However the remediation process is slow and generally takes longer than a year. Sources of toxic metals in contaminated areas in Hong Kong are mainly due to historic industrial discharge although present activities also contribute. Potential areas include sites for electronic waste activities, sediments of Kwun Tong typhoon shelter and sediments of Tolo Harbour.published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management
12
Kraemer, Ute. "Nickel hyperaccumulation in the genus Alyssum L". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318487.
Testo completo
13
Al-Asheh, Sameer. "Sorption of heavy metals by biological materials". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26101.pdf.
Testo completo
14
Warren, Robert Stephen. "Heavy metals in urban street surface sediments". Thesis, Middlesex University, 1987. http://eprints.mdx.ac.uk/13575/.
Testo completoAbstract (sommario):
A literature survey has been undertaken of the sources, levels and effects of heavy metal pollution in the urban street environment. Established techniques for the determination of heavy metal levels in urban dusts have been reviewed, and appropriate methods selected for use in the research project. Spatial and temporal variations of Cd, Cu, Pb and Zn in street dust have been investigated at a number sites. Metal loadings showed stronger spatial variation than concentrations with the greatest metal loadings occurring in the gutters and kerbsides. The results have been assessed in terms of surface type and condition, traffic loadings and antecedent weather conditions. The chemical associations of heavy metals in street dust, and their relationships to particle size have been investigated. Lead and Zn were associated mainly with carbonates and Fe-Mn oxides, whereas Cu is largely found in the organic fraction. Cadmium shows the greatest affinity for the exchangeable phase, and is therefore considered the most environmentally mobile metal studied. In addition to the studies mentioned above levels and chemical associations of heavy metals In school playground dust contaminated by paint flakes have been investigated. The levels of Pb were much higher than those previously reported. Exchangeable Pb concentrations represented a significant hazard to children playing in the area. In addition to the studies mentioned above levels and chemical associations of heavy metals In school playground dust contaminated by paint flakes have been investigated. The levels of Pb were much higher than those previously reported. Exchangeable Pb concentrations represented a significant hazard to children playing in the area. The final stage of the research project involved the operation of a sampling network to establish a mass balance for Cd, Cu, Pb and Zn within a residential urban street. Metal levels in atmospheric deposition, street sediments and runoff were monitored over an eight week period. Stormwater runoff was found to remove only a minor fraction of the metal deposited in the catchment during the sampling period.
15
Agarwal, P. "Magnetism and superconductivity in heavy-fermion metals". Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595373.
Testo completoAbstract (sommario):
One of the key challenges of contemporary condensed matter physics is to understand how the large variety of states of matter arises in electron systems. While the basic force is in all cases the electrostatic Coulomb interaction, the variety of states of matter spans an impressively broad spectrum, ranging from insulators to superconductors, and including a variety of magnetic phases. In recent years, a series of new, emergent phenomena have added more exotic states to the list of known behaviour in metallic systems, and some of them defy the standard descriptions of 'normal' metals, known as Fermi liquid theory. Examples of these new phenomena include the fractional quantum-Hall effect, high temperature superconductivity and magnetic quantum phase transitions, which are at the focus of this dissertation. Such phase transitions occur when magnetic order is suppressed at low temperatures by means of an external control parameter, such as pressure, doping or applied field. In the vicinity of such a transition, unusual properties are expected due to strong, long range magnetic interactions, which can lead to unconventional normal states and, quite generally, to exotic forms of superconductivity. More specifically, I have studied high purity single crystals of two f-electron metals, namely CeNi2Ge2 and UGe2, both close to their critical lattice densities, and examined the behaviour of their electrical resistivity as a function of temperature and pressure. CeNi2Ge2 at ambient pressure is naturally very close to antiferromagnetic ordering, and for the first time, CeNi2Ge2 is shown to be an unconventional superconductor at ambient pressure at about Tc ≃ 200mK. Furthermore, the normal state of CeNi2Ge2 displays an unconventional power-law of the form Δp T1.2 over 2 decades in temperature. As pressure is applied a slow return to Fermi liquid behaviour is observed at the lowest temperatures, before a second (and as yet unidentified) ordered phase sets in at high pressures. The second system studied in this dissertation is the ferromagnet UGe2, in which magnetism can be suppressed by pressures of about 1.4 GPa. In this material, too, superconductivity is observed at low temperatures over a narrow pressure range, but in the ferromagnetically ordered phase. I present preliminary measurements together with a phase diagram. It seems that UGe2 is the first example of an itinerant ferromagnetic superconductor. Experimental work was carried out using a new adiabatic demagnetization cryostat, specially designed and built as an important part of the research project. The thesis describes the design of the instrument, which allows high sensitivity measurements of the resistivity over a wide range in temperature with high reliability.
16
Mowll, J. L. "The responses of fungi to heavy metals". Thesis, University of Dundee, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234237.
Testo completo
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Mansi, Sadoniben E. "Heavy metals and their ecotoxicology in estuaries". Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426006.
Testo completo
18
Md, Noh Mohd Fairulnizal. "Electrochemical sensors development for toxic heavy metals". Thesis, Cranfield University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422358.
Testo completo
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Wainaina, Steven. "Effect of heavy metals on syngas fermentation". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10203.
Testo completoAbstract (sommario):
The goal of this work was to establish the suitable and limiting concentrations of Zn, Cu and Mn compounds during syngas fermentation. The results showed that cells encased in polyvinylidene difluoride (PVDF) membranes had a faster accumulation of methane in reactors containing fermentation medium dosed with 5 mg/L of each heavy metal compared to free cells. It was also revealed that total inhibition of biohydrogen production occurred in medium containing 5 mg/L Cu, 30 mg/L Zn and 140 mg/L Mn while the most suitable metal concentration level was 0.1 mg/L Cu, 0.6 mg/L and 2.8 mg/L Mn. In addition, a comparison test showed that for the most suitable metal concentration in the medium, rate of performance at pH 6 and 7 was higher than at pH 5.
20
Santos, Pedro Deyrieux Centeno Ogando. "Heavy metals removal in dual media filters". Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8251.
Testo completoAbstract (sommario):
Dissertação para obtenção do Grau de Mestre em
Engenharia do Ambiente – Perfil de Engenharia SanitáriaThe purpose of this study was to investigate physicochemical mechanisms for the removal of heavy metals from the effluent of Harnaschpolder’s WWTP Pilot Installation in the South of Netherlands. This effluent is partially submitted to tertiary treatment in a water reuse pilot which aims the production of water for two different end‑uses: crop irrigation in greenhouses and surface‑type water. Tertiary filters were mounted and started up at the reuse pilot and specific concentrations of heavy metals were dosed in the filters. Removal efficiencies were then calculated after the end of the experiments. As a parallel research project, the removal of HM was also carried out by inoculating selected bacteria (biosorption). Solubility curves were calculated for the dosed heavy metals (Cd, Cu, Ni, Zn) using PHREEQc programme, to predict if heavy metal precipitation occurred in the filters (using the same experimental data: temperature, pH , alkalinity, etc.). Results show that physicochemical precipitation was not the primary removal mechanism for heavy metals. The results suggest that other mechanisms such as adsorption and/or chelation may be involved in the removal of these species.
21
Kirk, Charles A. C. "Geochemical fractionation of heavy metals in soils". Thesis, University of Bristol, 1995. http://hdl.handle.net/1983/2153b6ab-75d5-4b4f-b648-f3ff6795b4d9.
Testo completo
22
Kwan, Sai-ping. "Heavy metals in Hong Kong rabbitfish (Siganus canaliculatus) /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20667759.
Testo completo
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Gomez, Katherine Emma. "Phytoremediation of contaminated soil from a petroleum refinery land treatment unit". Cincinnati, Ohio : University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1006197725.
Testo completo
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Malbrue, Courtney Michelle. "An Examination of Heavy Metal Vaporization from the Combustion of Black Liquor". Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13949.
Testo completoAbstract (sommario):
The research focuses on the fate of heavy metals and their emissions from pulp mill recovery boilers. Heavy metals are extremely toxic and cause adverse effects on human health. There is limited information about factors affecting heavy metal vaporization from recovery boilers, in which spent pulping liquors, (also called black liquor) is burnt. The heavy metals are present in trace quantities in black liquor. They are emitted in the air as submicron particles, and their amount of emission depends on the input of metals into the recovery boiler, volatilization of metals in the boiler and the efficiency of the electrostatic precipitator (ESP) to remove the metals. The heavy metals vaporization from different recovery boilers vary widely and the reason is not known. My thesis will focus on determining what conditions affect the volatility of the heavy metals, and whether differences in heavy metal vaporization are due to differences in boiler operating conditions or the composition of the liquor.
I will examine black liquor pyrolysis, combustion and gasification in well-controlled laboratory conditions. I will analyze three different black liquors. The liquors will be spray-dried and burnt or gasified in a laminar entrained-flow reactor at high temperatures of 1000-1100C and residence times ranging from 0.5 to 1.5 s. Equilibrium calculations will be performed to determine the distribution of heavy metals and species under set conditions from previous devolatilization experiments. The equilibrium calculations will serve as a useful tool for prior estimation of the distribution of heavy metals. The impact of different liquors on volatilization of heavy metals in the experiments will be determined. The char residue and condensation aerosol (fume) particles from each experiment will be analyzed using ICP-AES. The amount of heavy metals volatilization during combustion and gasification will be determined based on the amount of the metals in the char residues and fume particles.
Based on the results of the experimental study combined with data from the equilibrium analysis program the main cause of variability in heavy metal vaporization can be found. Also the boiler operating conditions can be studied to determine its affects on the volatility of the heavy metals.
25
Chow, Edith Chemistry Faculty of Science UNSW. "Peptide modified electrochemical sensors for the detection of heavy metal ions". Awarded by:University of New South Wales. Chemistry, 2006. http://handle.unsw.edu.au/1959.4/23354.
Testo completoAbstract (sommario):
In this research, the determination of trace concentrations of heavy metal ions was investigated using peptide modified electrochemical biosensors. The biosensor has several advantages over atomic absorption spectroscopy and inductively coupled plasma mass spectrometry by offering greater simplicity in use and the possibility of determining the bioavailability of heavy metals. Oligopeptides were modified on the electrode surface through the spontaneous self-assembly of thiols on gold. Firstly, 3-mercaptopropionic acid (MPA) was self-assembled onto the gold surface followed by activation of the carboxyl groups using a combination of carbodiimide and succinimide chemistry for coupling of the N-terminus of the peptide to occur. Using this generic strategy, Gly-Gly-His was used for the determination of copper ions. Cu2+ was accumulated at the MPA-Gly-Gly-His modified electrode at open circuit potential followed by electrochemical measurements. The reduction of Cu2+ to form underpotential deposited copper in the Osteryoung square wave voltammogram was used for quantification. The influence of various factors on the performance was investigated and after the optimal conditions had been identified, the biosensor was used for Cu2+ calibration and was applied to the analysis of a real sample. For Cd2+ detection, two different peptides covalently attached to MPA were investigated, g-Glu-Cys-Gly (GSH) and His-Ser-Gln-Lys-Val-Phe, with the latter sensor exhibiting a lower Cd2+ detection limit, higher sensitivity and greater selectivity. Although the success of MPA as a peptide linker to the gold surface had been shown for the detection of Cu2+ and Cd2+, a more viable approach was necessary for the stable detection of a wider range of metal ions. A more stable self-assembled monolayer of thioctic acid (TA) was identified in which human angiotensin I was attached. This alternate modification procedure was superior to MPA-angiotensin I for Pb2+ detection in terms of stability and reusability with the drawback being sensitivity. The newly identified strategy was also applied to the determination of Ag+ using TA-methionine enkephalin modified electrodes. A sensor array for Cu2+ was also investigated as well as an extension to the simultaneous determination of multianalytes using four different modified electrodes. Combining a soft-modelling approach, the responses of Cu2+, Cd2+ and Pb2+ could be deconvoluted.
26
Claus, Sonia Carmel, University of Western Sydney, of Science Technology and Environment College e of Science Food and Horticulture School. "Heavy metals in biota from temperate Australian estuaries". THESIS_CSTE_SFH_Claus_S.xml, 2003. http://handle.uws.edu.au:8081/1959.7/503.
Testo completoAbstract (sommario):
The detection of anthropogenic impacts in our estuaries has become a critical social, political and scientific concern in recent years. Work has focussed on the effects of these impacts on the spatial and temporal patterns of biotic assemblages and searched for bioindicators and biomarkers of pollutants that may act as early warning signs. The estuaries in temperate Southeastern Australia have a diversity of biotic assemblages living in the soft sediment. One of the most abundant macroinvertebrates is the little studies mussel, Xenostrobus securi that is found living with an assemblage of benthic biota including amphipods, crabs, isopods and tanaids, bivalves and gastropods. Two commercial fish species bream and mullet also inhabit these estuaries. Numerous stormwater drains can be found entering the estuaries through the mangrove forests lining the shores. Along with inputs of freshwater, stormwater drains are thought to be responsible for the entry of heavy metals into estuaries. These heavy metals have the potential to alter the patterns of biotic assemblages and bioaccumulate in the tissues of miacroinvertebrates, mussels and fish living within temperate estuaries. Over the time of this study the concentrations of heavy metals in the sediment tissues and shell of X.Securis varies spatially and temporally. Although this study adds substantially to current knowledge there is still more that is needed to establish X. Securis as a bioindicator. Questions remain about uptake, depuration and response to environmental gradients of heavy metals in X. Securis. Before X Securis can be used routinely in monitoring heavy metal contamination these questions need to be further investigatedDoctor of Philosophy (PhD)
27
Nkqenkqa, Vuyiseka. "Metal and microbial contamination of agricultural soil and the Veldwachters River, Stellenbosch, South Africa". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2423.
Testo completoAbstract (sommario):
Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2017.Surface water is used as a source of water supply in many countries, including South Africa. One of the sources of surface water pollution is leachate and surface runoff from landfills. In agricultural soils, the landfill runoff and leachate deteriorate the quality and affect the fertility of soil. The entry of metals and microorganisms from landfill leachate to adjacent environments is through surface runoff due to rainfall. Adverse effects on human- and environmental health triggers a need to monitor and control contaminants in the environment. The aims of the study are to determine the effect of landfill runoff and leachate on agricultural soil and river water (Veldwachters River) running adjacent to the Devon Valley landfill site and to identify potential metal-tolerant organisms in environmental samples collected in Stellenbosch, Western Cape, South Africa. Samples (agricultural soil, river water and sediments) were collected once a month for a period of six months from the study area for analysis. Physicochemical parameters that are known to have major effects on environmental samples were assessed and the concentrations of various metals (Al, Pb, Cr, Mn, Mo, Co, Ni, Cu, Zn, Fe, Cd and V) were also determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Soil texture analysis was tested in order to monitor the metal distribution in soils under the influence of environmental factors.
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Barros, Arielle Muniz de. "Bioadsorção e dessorção dos íons 'Cd POT. 2+', 'Cu POT. 2+' , 'Ni POT. 2+', 'Pb POT. 2+' e 'Zn POT. 2+' pela macrófita aquáica Azolla pinnata". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266685.
Testo completoAbstract (sommario):
Orientadores: Meuris Gurgel Carlos da Silva, Sirlei Jaiana KleinübingDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Pesquisas no campo da tecnologia têm buscado avaliar técnicas e/ou processos econômicos e eficientes para o tratamento de efluentes que contenham metal pesado. Atualmente a bioadsorção vem se apresentando como uma boa alternativa às tecnologias existentes. Este trabalho teve como objetivo a investigação da macrófita Azolla pinnata como bioadsorvente de cinco íons metálicos: Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+ em soluções sintéticas. A caracterização do biomaterial foi realizada utilizando-se técnicas como Microscopia Eletrônica de Varredura (MEV) para análise da superfície do material; análise de Espectroscopia de Energia Dispersiva de Raios-X (EDX), que mostrou que qualitativamente a diminuição de íons de competição (Ca, Na e K) após o processo de adsorção, evidenciando que a troca iônica pode ser um dos mecanismos do processo; e análise de Infravermelho por Transformada de Fourier (FTIR), em que se pôde constatar que alguns grupos funcionais como carboxilas e grupos sulfonados são fundamentais no processo. A cinética de adsorção foi ajustada pelos modelos de pseudoprimeira e pseudossegunda ordem, sendo que o melhor ajuste variou de acordo com o íon estudado. O modelo de difusão intrapartícula mostrou que muitos mecanismos podem ser limitantes na taxa com a qual ocorre o processo. Os dados de equilíbrio foi ajustado pelos modelos de isoterma de Langmuir e de Freundlich em duas temperaturas, 25 e 45 ºC. O processo foi favorecido pelo acréscimo de temperatura para todos os íons. O modelo de Langmuir se ajustou melhor aos dados experimentais de todos os íons e o valor de capacidade máxima de adsorção (qmax) a 25 ºC foi de 0,359; 0,448; 0,254; 0,472 e 0,357 mmol/g para Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+, respectivamente. Os eluentes HCl, EDTA e CaCl2 foram testados no processo de dessorção em batelada e o cloreto de cálcio se mostrou eficiente além de não causar danos ao material nem diminuir a capacidade de adsorção da macrófita. Ensaios dinâmicos em coluna de leito fixo foram realiados para os íons Cu2+ e Pb2+ com soluções mono e bicomponentes. Nos ensaios em sistema binários, pode-se constatar uma grande preferência pela adsorção de íons chumbo e, portanto, uma grande queda na adsorção de cobre. Foram testados ciclos de adsorção/dessorção em coluna utilizando o CaCl2 como eluente e, em três ciclos, a macrófita manteve suas propriedades adsortivas. Com estes resultados, pode-se constatar que a realização deste trabalho contribuiu para a avaliação deste material como bioadsorvente alternativo e que, especificamente, macrófita A. pinnata mostrou-se atrativa para utilização nos processos de tratamento e/ou estabilização de metais pesados presentes em baixas concentrações em efluentes industriais
Resumo: No processo Kraft para produção de papel e celulose, os cavacos de madeira são cozidos em um digestor com uma solução aquosa denominada licor branco, constituída de hidróxido de sódio (NaOH) e sulfeto de sódio (Na2S). Durante o cozimento uma pasta fibrosa é produzida. Esta pasta é filtrada e segue para o branqueamento. O produto filtrado chama-se licor negro, devido à mudança da sua cor nesta etapa. O licor negro possui aproximadamente 15 % de sólidos em massa. Ele é bombeado para a unidade de recuperação, na qual ele será concentrado em evaporadores de múltiplosefeitos até 75 % de sólidos em massa. Em seguida, ele é bombeado para uma caldeira onde é queimado, para recuperar os sais inorgânicos e, principalmente, fornecer calor para geração de calor. Durante a evaporação do licor negro, quando a porcentagem em sólidos ultrapassa 50 %, ocorre a precipitação de sais inorgânicos. Estes sais se depositam nas superfícies de troca térmica dos evaporadores diminuindo sua eficiência e causando prejuízos à indústria. Os principais sais que causam este problema são o carbonato de sódio (Na2CO3) e o sulfato de sódio (Na2SO4). O objetivo do presente trabalho foi testar e validar um método experimental para a determinação da quantidade de Na2CO3 presente em amostras industriais de licor negro. Além disso, também foram analisadas algumas propriedades físico-químicas do licor negro, como massa específica, teor de sólidos e viscosidade. Com os resultados obtidos, tentou-se obter uma correlação entre o teor de carbonato de sódio e as demais propriedades do licor que foram determinadas. Os resultados das análises das características físico-químicas demonstraram coerência e boa reprodutibilidade, porém, os resultados das análises de teor de carbonato de sódio não foram satisfatórios e mostraram que a técnica deve ser aperfeiçoada
Abstract: Research in the technology field has been looking for evaluating efficient and economic techniques and/or process for effluents that contains heavy metal. The biodsorption process has been seemed as a good alternative to the existing technology. This work had the aim to investigate the use of Azolla pinnata macrophyte as biosorbent of five metallic ions: Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+ in synthetic solutions. The biomaterial characterization was carried out by techniques as scanning electron microscopy (SEM) for the analyze of material superficies; the energy dispersive X-ray spectroscopy (EDX), which showed, qualitatively, a decreasing in the competitions ions (Ca, Na e K) after the sorption process, indicating that the ion exchange can be one o the process mechanism; and Fourier Transform Infrared Spectroscopy (FTIR), in which it was possible implied functional groups as carboxyl and sulfonate play a important role in the adsorption. The kinetics was adjusted by primer and second order models and the model which fit better depends on each ion. The intra-particle diffusion model showed that several mechanisms may be limiting to the process rate. The equilibrium data were adjusted by Langmuir and Freundlich models in two temperatures: 25 and 45 ºC. The process was favored by the increasing in the temperature for all five ions. The Langmuir model fit better the experimental data and the maximum adsorption capacity (qmax) were 0,359; 0,448; 0,254; 0,472 and 0,357 mmol/g for Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+, respectively. The HCl, EDTA and CaCl2 eluents were tested in the desorption process and the calcium chloride was efficient and did not cause any damage in the biomaterial or decreasing the biosorption capacity. Dynamics runs were carried out in fixed-bed in mono and bi-components solutions. In the binary were found a great preference for lead instead of copper and as a result, a significant decrease in the removal of copper. Adsorption/desorption cycles were tested in fixed-bed system using CaCl2 as eluent. After three cycles no damage, weight lost or significant decrease in the biosorption capacity was noticed. These results indicating that the A.pinnata macrophyte is an attractive potential new biosorbent to be used in heavy metal removal especially in low concentrations effluents
Abstract: In the Kraft process for pulp and paper production, wood chips are cooked in a digester with an aqueous solution named white liquor, consisted by sodium hydroxide (NaOH) and sodium sulfide (Na2S). During this cooking process, wood chips are transformed generating a fibrous paste and a liquid solution. This paste is filtered and separated from the liquid solution, named black liquor due to its color. The paste goes to the bleaching stage to produce cellulose. Black liquor contains inorganic and organic (mainly lignin) compounds from wood. Initially this black liquor contains approximately 15 mass/% of solids and is sent to the recovery unit to have this concentration raised to approximately 75 mass/% to be burned in a recovery boiler in order to generate power and recover inorganic reactants, recycling them to the process. The concentration process of black liquor occurs in a multiple effect evaporators unit. During this process, when the concentration of solids exceeds 50%, the precipitation of inorganic salts (mainly Na2CO3 and Na2SO4) begins. These salts are deposited in the heat transfer surfaces of the evaporator tubes, reducing their efficiency, leading to a reduction in the production capacity. The scope of this work was testing and validate an experimental method to estimate the content of Na2CO3 present in industrial black liquor samples. Moreover, some black liquor's physical-chemical properties as density, solids content and viscosity were also analyzed. An attempt to develop a predictive model to evaluate sodium carbonate content from the other properties was made. The results obtained for physical-chemical properties have shown a good consistency. However, the results of sodium carbonate analyses were not satisfactory, showing that the technique must be improved
Mestrado
Engenharia de Processos
Mestra em Engenharia Química
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Lindström, Martin. "Predictive Modelling of Heavy Metals in Urban Lakes". Doctoral thesis, Uppsala University, Department of Earth Sciences, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-530.
Testo completoAbstract (sommario):
Heavy metals are well-known environmental pollutants. In this thesis predictive models for heavy metals in urban lakes are discussed and new models presented. The base of predictive modelling is empirical data from field investigations of many ecosystems covering a wide range of ecosystem characteristics. Predictive models focus on the variabilities among lakes and processes controlling the major metal fluxes.
Sediment and water data for this study were collected from ten small lakes in the Stockholm area, the Eastern parts of Lake Mälaren, the innermost areas of the Stockholm archipelago and from literature studies. By correlating calculated metal loads to the land use of the catchment areas (describing urban and natural land use), the influences of the local urban status on the metal load could be evaluated. Copper was most influenced by the urban status and less by the regional background. The opposite pattern was shown for cadmium, nickel and zinc (and mercury). Lead and chromium were in-between these groups.
It was shown that the metal load from the City of Stockholm is considerable. There is a 5-fold increase in sediment deposition of cadmium, copper, mercury and lead in the central areas of Stockholm compared to surrounding areas.
The results also include a model for the lake characteristic concentration of suspended particulate matter (SPM), and new methods for empirical model testing. The results indicate that the traditional distribution (or partition) coefficient Kd (L kg-1) is unsuitable to use in modelling of the particle association of metals. Instead the particulate fraction, PF (-), defined as the ratio of the particulate associated concentration to the total concentration, is recommended. Kd is affected by spurious correlations due to the definition of Kd as a ratio including SPM and also secondary spurious correlations with many variables correlated to SPM. It was also shown that Kd has a larger inherent within-system variability than PF. This is important in modelling.
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Lindström, Martin. "Predictive modelling of heavy metals in urban lakes /". Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2000. http://publications.uu.se/theses/91-554-4854-2/.
Testo completo
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Claus, Sonia Carmel. "Heavy metals in biota from temperate Australian estuaries /". View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051013.092820/index.html.
Testo completoAbstract (sommario):
Thesis (Ph.D.) -- University of Western Sydney, 2003."Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.
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Li, Litong. "Heavy metals removal from wastewater by peat absorption /". Connect to online version, 1996. http://hdl.handle.net/1989/3561.
Testo completo
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Rose, C. J. S. "The uptake of heavy metals by three seaweeds". Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638712.
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Khastoo, D. "Uptake and toxicity of heavy metals in insects". Thesis, Swansea University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637787.
Testo completoAbstract (sommario):
The effects of some heavy metals at different stages of food chains are examined. The uptake of Zn or Cd by Australian white wheat, Triticum aestivum, was investigated and this wheat fed to the herbivore, Schistocerca gregaris. The organs of these insects were then examined for accumulation. Accumulation occurred in all organs examined but was higher in the epidermis and mid-gut. Nasonia vitripennis (Hymenoptera) was used as a carnivore. The effects of Zn, Cd, Cu and Hg on the longevity and survival of this insect were examined together with total accumulation at three different temperatures. Metals were more toxic at higher temperatures and the effects of different metals varied. The effects on the ultrastructure of flight muscles were examined, the main effect being a disruption of the mitochondria.
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Kwan, Sai-ping, e 關世平. "Heavy metals in Hong Kong rabbitfish (Siganus canaliculatus)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221038.
Testo completo
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Jones, J. M. "Magnetic minerals and heavy metals in ombrotrophic peat". Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372671.
Testo completo
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Muhammad, Nur. "Removal of heavy metals by slow sand filtration". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/6981.
Testo completoAbstract (sommario):
Slow sand filters (SSFs) are probably the most effective, simplest and least expensive water treatment process. Micro-organisms and other particulate materials are effectively removed by SSFs. Considerable development has been done on SSFs with respect to particle removal, but only a few works have been reported in the context of the removal of heavy metals which are a severely toxic pollutant of surface waters. No extensive laboratory or pilot studies have been carried out to determine the performance or the mechanisms of removal of heavy metals by SSFs. This research is concerned with an experimental investigation of the removal of heavy metals from surface water by SSFs. Four laboratory scale SSFs were built and run according to standard design criteria. Removal of four common heavy metals [copper (Cu), chromium (Cr), lead (Pb) and cadmium (Cd)] were monitored. The filters were fed synthetic water made from tap water mixed with settled sewage, and each filter was dosed with one of the heavy metal salts. The concentrations of Cu, Cr, Pb and Cd in the influent were selected as 10 mg/l, 100 μg/l, 60 μg/l, and 100 μg/l respectively considering their relative toxicity and WHO guidelines in drinking water. Settled sewage was added to vary the total organic carbon (TOC) of the feed water. The reduction of heavy metal concentrations were monitored at various TOCs, filtration rates and filter bed depths. The results showed that SSFs succeeded in removing heavy metals from water. The removals of Cu, Cr, Pb and Cd at the conventional flow rate and filter depth are 99.6,97.2,100 and 96.6 % respectively. The results also showed that an increase in TOC in the feed water improved metal removal while increases of flow rates caused a decrease of the removal of metals. The removal of heavy metals also decreased with a reduction in sand bed depth. The optimisation of design parameters for SSFs for the removal of heavy metals depends on the individual heavy metal and on the TOC content of the feed water. Model equations were developed for, and linear correlation was observed between each of the three control parameters and the removal of the selected metal. The removal of heavy metal by SSFs was achieved through the combination of a number of mechanisms. Settlement, adsorption to both sand and organic matter and microbial
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Rome, Jacqueline Louise de. "Biosorption of heavy metals by fungi and yeast". Thesis, University of Dundee, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338281.
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Tompkins, Joanne Deborah. "The uptake of heavy metals into human phagocytes". Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243177.
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PINO, GABRIELA ALEJANDRA HUAMAN. "BIOSSORPTION OF HEAVY METALS ON GREEN COCONUT POWDER". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7596@1.
Testo completoAbstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA poluição por metais pesados vem se tornando um sério problema ambiental. O uso de biomassas como material sorvente para a destoxificação de efluentes industria is contendo metais aparece como uma alternativa promissora às tecnologias existentes. O objetivo desta dissertação foi determinar a capacidade de adsorção da casca de coco (Cocos nucifera) para diferentes metais pesados. No processo de biossorção foram ava liados o pH da solução, a concentração inicial dos íons metálicos, o tamanho de partícula e a cinética do processo. As características da superfície da casca de coco foram investigadas utilizando medições de potencial zeta e análises com microscópio eletrônico de varredura. Obtiveram-se altas percentagens de remoção para o Cd, Cr(III) e Cr(VI) dentre as seis espécies metálicas estudadas (As(V), Cd, Cr(III), Cr(VI), Ni e Zn). Os valores ótimos de pH utilizados foram de 7 para o cádmio e cromo (III) e de 2 para o cromo (VI). Em concentrações inicias inferiores a 100 mg/L foram obtidas percentagens de remoção superiores a 95%, 85% e 80% para o cádmio, cromo (III) e cromo (VI), respectivamente. Em concentrações inicias menores que 1000 mg/L, a percentagem de remoção para o cádmio e o cromo (III) foi de 80% e 85%, respectivamente. Foram utilizados os modelos de Langmuir e Freundlich para avaliar a capacidade de adsorção de metais pesados pela casca de coco. O modelo de Langmuir mostrou-se mais adequado para o cádmio e o cromo (VI), enquanto que para o cromo (III) o modelo de Freundlich foi o mais adequado. A cinética do processo de biossorção foi estudada para o cádmio mediante as análises integral e diferencial. Foi observado que o processo de biossorção de cádmio por casca de coco verde obedece a um modelo de pseudo-segunda ordem. Os resultados apresentados mostram que a casca de coco apresenta as características apropriadas para o processo de biossorção de cádmio, cromo (III) e cromo (VI) e que pode ser utilizada como uma alternativa aos processos clássicos de destoxificação de efluentes.
Heavy metal pollution has become one of the most serious problems today, and the use of organic material biomass for the detoxification of industrial effluents for environmental protection offers a potential alternative to existing trea tment technologies. The aim of this work was determined the biosorption capacity of coconut fibers (Cocos nucifera) for different heavy metals. The effect of pH, initial concentration, size of particle and kinetics were studied. The characteristics of the surface of coconut fibers had been investigated using measurements of potential zeta and analyses with scanning electron microscope. The removal was found to be higher for cadmium, chromium (III) e chromium (VI) among the 6 metallic species studied (As, Cd, Cr (III), Cr (VI), Ni e Zn). The values of pH used were 7 for cadmium and chromium (III) and of 2 for chromium (VI). For cadmium, chromium (III) and chromium (VI), with an initial metal concentration lower than 100 mg/L, removal rates of 95%, 85% and 80% respectively had been observed. For cadmium and chromium (III), with an initial concentration lower than 1000 mg/L, removal rates of 80% and 85% respectively were found. The adsorption capacity of coconut fibers for heavy metals had been evaluated using Langmuir and Freundlich adsorption isotherms. The Langmuir´s model gave best results for cadmium and chromium (VI) and Freundlich´s model for chromium (III). The kinetics of the process was studied just for cadmium, because it presented the best removal rates. The kinetics study showed that the biosorption process followed a pseudo second order model. This suggests that coconut fibers represent a good option for biosorption process and can be used as an alternative to the classical technologies for effluent decontamination.
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Chatterjee, Sabyasachi. "Calcite and Calcium Oxalate Sequestration of Heavy Metals". Diss., Temple University Libraries, 2009. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/50093.
Testo completoAbstract (sommario):
EngineeringPh.D.
Heavy metals like cadmium, lead and zinc pose a significant threat to human health and environment. Several factors such as pH, EH, organic matter and clay content of the soil affect the bioavailability of such heavy metals in the environment. The presence of several naturally occurring minerals such as calcite (calcium carbonate, CaCO3) and calcium oxalate (CaC2O4.) in the environment significantly influence the fate and transport of some of the heavy metal cations. Sequestration of heavy metals such as cadmium (Cd) and zinc (Zn) from solution by calcite has been clearly demonstrated in the literature. However, studies on heavy metal sequestration by calcite and calcium oxalate from a multi-metal environmental that represents real world situations are rare. In this contribution, column flow studies of Cd and Zn sequestration by calcite exposed to influent solutions saturated or non-saturated with calcite and containing either 1 mg/L of Cd, 1 mg/L of Zn or combined 1 mg/L of Zn and Cd, followed by desorption of the sequestered metals were conducted. Complementary scanning electron microscopy (SEM) coupled with electron dispersive x-ray spectroscopy (EDS) data were generated. Kinetic studies show that reaction rates of Cd and Zn with calcite are governed by a simple rate law with reaction orders of less than 1 (0.02 - 0.07) indicating at least mathematically, the occurrence of reactions that went to completion if the reaction orders did not change. When the influent solution contains a single cation, the rate of Zn removal from solution by calcite and calcium oxalate is greater than Cd removal rate. However in a multi-cation environment, cadmium removal rate was greater than zinc removal rate. MINTEQA2 a geochemical equilibrium speciation model was used to compute the equilibrium between the various species in the cation-calcite environment. Complimentary desorption studies and surface SEM/EDS analysis indicate that the removal of Cd and Zn from solution by calcite and calcium oxalate is probably due to precipitation/complexation reaction. The SEM and EDS results appear to confirm the presence of a precipitate on the mineral surface in the case of the influent solution containing Zn. The current research also examines the effect of citrate, a commonly present urinary tract species on calcium oxalate dissolution. The dissolution studies indicate that citrate solution is capable of dissolving sodium oxalate at high pH. The dissolution of calcium oxalate results in the release of heavy metals that were previously sequestered within the mineral. Results show that a greater percentage of zinc was removed than cadmium, from calcium oxalate due to its dissolution by citrate.
Temple University--Theses
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Paul, Uchenna Prince. "Fluorescence Detectors for Proteins and Toxic Heavy Metals". Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd416.pdf.
Testo completo
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Mathur, Neil David. "Quantum order in heavy fermion systems". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388485.
Testo completo
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Strelko, Vladimir. "Selective removal of heavy metals using novel active carbons". Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/7182.
Testo completoAbstract (sommario):
Porous carbonaceous adsorbent materials possessing weakly acidic surface functional groups have been evaluated for the selective removal of heavy metals from aqueous solutions. Active carbons derived from both agricultural products (KAU carbons) and polymeric resin (CKC carbon) have been oxidised by hot air or nitric acid to produce samples with different degrees of surface oxidation. A novel phosphorus-containing carbonaceous sorbent (PGP-P) has been prepared by pyrolysis of phosphorylated phenol-formaldehyde resin. Surface modifications have been carried out to introduce various acidic functional groups capable of selective heavy metal binding. The properties of these sorbents have been compared to those of commercially available polymeric carboxylic resin C 104 (Purolite) and oxidised Filtrasorb 400 (Chemviron). Investigation into the physical structure of the adsorbents using microscopy and nitrogen sorption at liquid nitrogen temperatures showed that the porous structure is adversely affected by carbon oxidation. The surface area and pore volume decrease as the degree of surface oxidation increases. The low surface area and pore volume of PGP-P was attributed to the presence of phosphorus-containing functional groups which protect the surface from excessive burn-off. The surface functionality of the sorbcnts was determined by FT-IR, NMR and X-ray photoelectron spectroscopy. Relatively high concentrations of different weakly acidic functional groups were detected on the surface of the materials studied. The ion-exchange properties of the sorbents were assessed by acid-base titration techniques and electrophoretic mobility measurements. Oxidation of carbons with hot air resulted in a greater proportion of relatively weaker type surface functionality (i.e. phenolic) whereas nitric acid modification produced a higher concentration of relatively stronger carboxylic groups. Electrophoretic mobility measurements suggested that the carbon surface is negatively charged within the range of pH values studied. pH titration results demonstrated relatively greater surface acidity of active carbons compared to carboxylic resin. Active carbons were successfully applied for the selective removal of radionuclides. The materials showed excellent decontamination factors for a-, b- and y emitters. This was attributed to the presence of mineral admixtures and humic acids in carbons as well as the surface functional groups. Repeated cycles of lead sorption/elution indicated that the metal capacities of the carbon-packed mini-columns were reduced but reached a steady level after 3-4 cycles.
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Le, Huquet Jeannette Anne. "Heavy metal-regulated gene expression in flowering plants". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241491.
Testo completo
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Fang, Bin. "Remobilisation of heavy metals from sediments using aminopolycarboxlyic acids". Connect to full text, 2005. http://hdl.handle.net/2123/630.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Sydney, 2005.Title from title screen (viewed 21 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Centre for Heavy Metals Research, School of Chemistry, School of Chemistry. Includes bibliographical references. Also available in print form.
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Zogaj, Muhamet [Verfasser]. "Heavy metals and plant uptake of metals in agricultural soils of Kosovo / Muhamet Zogaj". Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1151046779/34.
Testo completo
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Feeney, Rosemary. "Development, demonstration, and validation of microfabricated iridium and gold arrays for the field screening of heavy metals in ground water /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2002.
Cerca il testo completoAbstract (sommario):
Thesis (Ph.D )--Tufts University, 2002.Adviser: Samuel P. Kounaves. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 104-111). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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O'Reilly, Wiese Siobhan Bernadette. "An investigation into historical metal accumulation in the sediments of the Thames estuary and in two eroding Essex salt marshes". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362463.
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Chuichulcherm, Sinsupha. "Configuration and operation of bioreactors for metal removal from wastewater systems using sulphate reducing bacteria". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249226.
Testo completo