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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The sorption of thorium, protacintium and plutonium onto silica particles in the presence of a colloidal third phase

Roberts, Kimberly Ann 15 May 2009 (has links)
The fate of actinides in the environment is of interest for a several reasons. In oceanic surface waters actinides such as thorium and protactinium, and in particular their ratio, are used as tracers of processes such as boundary scavenging and paleocirculation. Thorium is also used to estimate residence times and particle and colloid fluxes from the euphotic zone, which is useful in global carbon budgets used to assess effects of global warming. Terrestrially, contaminated areas in need of remediation, such as former nuclear weapons production facilities, remain as repositories for no longer needed actinide stockpiles or waste by-products such as plutonium. All three of these actinides: thorium, protactinium, and plutonium are known to be particle-reactive but the extent to which they sorb to immobile particles and mobile colloids can vary with environmental conditions. Understanding controls on adsorption is important in understanding uses and any limitations of these radioactive tracers caused by colloids. Often laboratory studies to understand actinide behavior are conducted at concentrations (micro- to millimolar), which are orders of magnitude higher than they are found in the environment (femto- to picomolar). Colloids, a size class of particles operationally defined as 1 nm to 1 µm in size, are ubiquitous in aquatic systems. The effect colloids have on actinide particle association, i.e. competitive or enhancing, can have a profound influence on the ultimate behavior of the actinide. The overall aim of this study is to assess sorption of thorium, protactinium and plutonium onto silica particles as a proxy for inorganic particles found in surface or ocean waters. In addition to the binary system of actinide/silica, the ternary system actinide/ organic colloid/ silica were also carried out to determine the affect of the organic colloid has on particle association. In particular, extracellular polymeric substances (EPS) extracted from laboratory grown bacteria and phytoplankton cultures were utilized as they too are ubiquitous in aquatic systems and have shown to strongly complex actinide ions, with EPS involved in oceanic scavenging of Th, as well as immobilization/mobilization of Pu in contaminated areas on land.
2

Sorption and transport of heterocyclic aromatic compounds in soils

Bi, Erping, January 2006 (has links)
Tübingen, Univ., Diss., 2006.
3

Multi-Hydrid Sorptionsanlage zur kombinierten Heizung und Kühlung

Willers, Eike. January 2002 (has links)
Stuttgart, Univ., Diss., 2002.
4

Influences on the sorption affinity of soil organic matter for non-ionic organic pollutants.

Ahangar, Ahmad G. January 2009 (has links)
Sorption of non-ionic organic compounds to organic matter is usually characterized as a partitioning interaction, which is quantified by K [subscript]oc, the organic-C normalized partitioning coefficient. However K [subscript]oc for any single compound varies considerably between soils, often by a factor of 3-10. This study addresses some of the potential causes of this variability. Forty-four soil cores were collected from a 2 ha paddock. Ten of these cores were selected for sorption measurements. The chemical composition of the soil organic matter (SOM) was determined using ¹³C NMR analysis. It was found that K [subscript]oc for diuron was positively correlated with aryl C (r² = 0.59) and negatively correlated with O-alkyl C (r² = 0.84). There were no such correlations for phenanthrene K [subscript]oc. A second set of experiments was carried out to investigate the effects of SOM– mineral interactions on the sorption properties of a selection of the soils. It was found that HF-treatment increased K [subscript]oc for both phenanthrene and diuron. The HF treatment removes mineral matter leaving the organic phase unaffected by the treatment. The increase in K [subscript]oc on HF-treatment soils provides strong evidence that interactions between organic matter and soil minerals block organic matter sorption sites. Furthermore, following HF-treatment, there was a positive correlation between K [subscript]oc for phenanthrene and aryl C and carbonyl C and a negative correlation with O-alkyl C. This suggests that the non-constancy of the relationship between organic matter chemistry and K [subscript]oc, for whole soils in the case of phenanthrene, may be a consequence of variability of the effect of organic matter-mineral interactions on K [subscript]oc. The influence of lipids on the sorption of diuron and phenanthrene to soils was also investigated. Lipids are known to cover the surfaces of organic matter in soil. K [subscript]oc for diuron and phenanthrene were consistently higher for the lipid-extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids block sorption sites on the organic matter. Sorption experiments on one pair of HF-treated soils indicated that the blocking effects of minerals and lipids are independent, because lipid extraction and HF-treatment combined increased K [subscript]oc by more than either treatment alone. In the last experiment, the effect of solvent conditioning on the sorption of diuron and phenanthrene was investigated. The K [subscript]oc values for compounds were consistently higher for solvent-treated whole soil and lipid-extracted soil than corresponding soils before solvent treatment. Solid-state ¹³C NMR spectra of the solvent-treated soils indicated that there were no significant changes in the chemical structure of SOM caused by solvent treatment. Solvent treatment changes the physical conformation of the SOM, increasing its sorption affinity. The key findings from the research are: • Variations in sorption affinity for diuron are related to differences in the soil organic matter chemistry. • SOM-mineral interactions can have a substantial influence on K [subscript]oc for non- ionic compounds. • Lipids may block the active sorption sites on the SOM thereby diminishing sorption overall. • Solvent conditioning can change the physical conformation of SOM and lead to enhancement sorption of diuron and phenanthrene. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1372068 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009
5

Influences on the sorption affinity of soil organic matter for non-ionic organic pollutants.

Ahangar, Ahmad G. January 2009 (has links)
Sorption of non-ionic organic compounds to organic matter is usually characterized as a partitioning interaction, which is quantified by K [subscript]oc, the organic-C normalized partitioning coefficient. However K [subscript]oc for any single compound varies considerably between soils, often by a factor of 3-10. This study addresses some of the potential causes of this variability. Forty-four soil cores were collected from a 2 ha paddock. Ten of these cores were selected for sorption measurements. The chemical composition of the soil organic matter (SOM) was determined using ¹³C NMR analysis. It was found that K [subscript]oc for diuron was positively correlated with aryl C (r² = 0.59) and negatively correlated with O-alkyl C (r² = 0.84). There were no such correlations for phenanthrene K [subscript]oc. A second set of experiments was carried out to investigate the effects of SOM– mineral interactions on the sorption properties of a selection of the soils. It was found that HF-treatment increased K [subscript]oc for both phenanthrene and diuron. The HF treatment removes mineral matter leaving the organic phase unaffected by the treatment. The increase in K [subscript]oc on HF-treatment soils provides strong evidence that interactions between organic matter and soil minerals block organic matter sorption sites. Furthermore, following HF-treatment, there was a positive correlation between K [subscript]oc for phenanthrene and aryl C and carbonyl C and a negative correlation with O-alkyl C. This suggests that the non-constancy of the relationship between organic matter chemistry and K [subscript]oc, for whole soils in the case of phenanthrene, may be a consequence of variability of the effect of organic matter-mineral interactions on K [subscript]oc. The influence of lipids on the sorption of diuron and phenanthrene to soils was also investigated. Lipids are known to cover the surfaces of organic matter in soil. K [subscript]oc for diuron and phenanthrene were consistently higher for the lipid-extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids block sorption sites on the organic matter. Sorption experiments on one pair of HF-treated soils indicated that the blocking effects of minerals and lipids are independent, because lipid extraction and HF-treatment combined increased K [subscript]oc by more than either treatment alone. In the last experiment, the effect of solvent conditioning on the sorption of diuron and phenanthrene was investigated. The K [subscript]oc values for compounds were consistently higher for solvent-treated whole soil and lipid-extracted soil than corresponding soils before solvent treatment. Solid-state ¹³C NMR spectra of the solvent-treated soils indicated that there were no significant changes in the chemical structure of SOM caused by solvent treatment. Solvent treatment changes the physical conformation of the SOM, increasing its sorption affinity. The key findings from the research are: • Variations in sorption affinity for diuron are related to differences in the soil organic matter chemistry. • SOM-mineral interactions can have a substantial influence on K [subscript]oc for non- ionic compounds. • Lipids may block the active sorption sites on the SOM thereby diminishing sorption overall. • Solvent conditioning can change the physical conformation of SOM and lead to enhancement sorption of diuron and phenanthrene. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1372068 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009
6

Influences on the sorption affinity of soil organic matter for non-ionic organic pollutants.

Ahangar, Ahmad G. January 2009 (has links)
Sorption of non-ionic organic compounds to organic matter is usually characterized as a partitioning interaction, which is quantified by K [subscript]oc, the organic-C normalized partitioning coefficient. However K [subscript]oc for any single compound varies considerably between soils, often by a factor of 3-10. This study addresses some of the potential causes of this variability. Forty-four soil cores were collected from a 2 ha paddock. Ten of these cores were selected for sorption measurements. The chemical composition of the soil organic matter (SOM) was determined using ¹³C NMR analysis. It was found that K [subscript]oc for diuron was positively correlated with aryl C (r² = 0.59) and negatively correlated with O-alkyl C (r² = 0.84). There were no such correlations for phenanthrene K [subscript]oc. A second set of experiments was carried out to investigate the effects of SOM– mineral interactions on the sorption properties of a selection of the soils. It was found that HF-treatment increased K [subscript]oc for both phenanthrene and diuron. The HF treatment removes mineral matter leaving the organic phase unaffected by the treatment. The increase in K [subscript]oc on HF-treatment soils provides strong evidence that interactions between organic matter and soil minerals block organic matter sorption sites. Furthermore, following HF-treatment, there was a positive correlation between K [subscript]oc for phenanthrene and aryl C and carbonyl C and a negative correlation with O-alkyl C. This suggests that the non-constancy of the relationship between organic matter chemistry and K [subscript]oc, for whole soils in the case of phenanthrene, may be a consequence of variability of the effect of organic matter-mineral interactions on K [subscript]oc. The influence of lipids on the sorption of diuron and phenanthrene to soils was also investigated. Lipids are known to cover the surfaces of organic matter in soil. K [subscript]oc for diuron and phenanthrene were consistently higher for the lipid-extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids block sorption sites on the organic matter. Sorption experiments on one pair of HF-treated soils indicated that the blocking effects of minerals and lipids are independent, because lipid extraction and HF-treatment combined increased K [subscript]oc by more than either treatment alone. In the last experiment, the effect of solvent conditioning on the sorption of diuron and phenanthrene was investigated. The K [subscript]oc values for compounds were consistently higher for solvent-treated whole soil and lipid-extracted soil than corresponding soils before solvent treatment. Solid-state ¹³C NMR spectra of the solvent-treated soils indicated that there were no significant changes in the chemical structure of SOM caused by solvent treatment. Solvent treatment changes the physical conformation of the SOM, increasing its sorption affinity. The key findings from the research are: • Variations in sorption affinity for diuron are related to differences in the soil organic matter chemistry. • SOM-mineral interactions can have a substantial influence on K [subscript]oc for non- ionic compounds. • Lipids may block the active sorption sites on the SOM thereby diminishing sorption overall. • Solvent conditioning can change the physical conformation of SOM and lead to enhancement sorption of diuron and phenanthrene. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1372068 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009
7

Influences on the sorption affinity of soil organic matter for non-ionic organic pollutants.

Ahangar, Ahmad G. January 2009 (has links)
Sorption of non-ionic organic compounds to organic matter is usually characterized as a partitioning interaction, which is quantified by K [subscript]oc, the organic-C normalized partitioning coefficient. However K [subscript]oc for any single compound varies considerably between soils, often by a factor of 3-10. This study addresses some of the potential causes of this variability. Forty-four soil cores were collected from a 2 ha paddock. Ten of these cores were selected for sorption measurements. The chemical composition of the soil organic matter (SOM) was determined using ¹³C NMR analysis. It was found that K [subscript]oc for diuron was positively correlated with aryl C (r² = 0.59) and negatively correlated with O-alkyl C (r² = 0.84). There were no such correlations for phenanthrene K [subscript]oc. A second set of experiments was carried out to investigate the effects of SOM– mineral interactions on the sorption properties of a selection of the soils. It was found that HF-treatment increased K [subscript]oc for both phenanthrene and diuron. The HF treatment removes mineral matter leaving the organic phase unaffected by the treatment. The increase in K [subscript]oc on HF-treatment soils provides strong evidence that interactions between organic matter and soil minerals block organic matter sorption sites. Furthermore, following HF-treatment, there was a positive correlation between K [subscript]oc for phenanthrene and aryl C and carbonyl C and a negative correlation with O-alkyl C. This suggests that the non-constancy of the relationship between organic matter chemistry and K [subscript]oc, for whole soils in the case of phenanthrene, may be a consequence of variability of the effect of organic matter-mineral interactions on K [subscript]oc. The influence of lipids on the sorption of diuron and phenanthrene to soils was also investigated. Lipids are known to cover the surfaces of organic matter in soil. K [subscript]oc for diuron and phenanthrene were consistently higher for the lipid-extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids block sorption sites on the organic matter. Sorption experiments on one pair of HF-treated soils indicated that the blocking effects of minerals and lipids are independent, because lipid extraction and HF-treatment combined increased K [subscript]oc by more than either treatment alone. In the last experiment, the effect of solvent conditioning on the sorption of diuron and phenanthrene was investigated. The K [subscript]oc values for compounds were consistently higher for solvent-treated whole soil and lipid-extracted soil than corresponding soils before solvent treatment. Solid-state ¹³C NMR spectra of the solvent-treated soils indicated that there were no significant changes in the chemical structure of SOM caused by solvent treatment. Solvent treatment changes the physical conformation of the SOM, increasing its sorption affinity. The key findings from the research are: • Variations in sorption affinity for diuron are related to differences in the soil organic matter chemistry. • SOM-mineral interactions can have a substantial influence on K [subscript]oc for non- ionic compounds. • Lipids may block the active sorption sites on the SOM thereby diminishing sorption overall. • Solvent conditioning can change the physical conformation of SOM and lead to enhancement sorption of diuron and phenanthrene. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1372068 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009
8

Preparation of Copolymers of Acrylic Acid and Acrylamide for Copper (II) Capture from Aqueous Solutions

Zhang, Yudong 01 October 2009 (has links)
Cross-linked copolymers of acrylic acid (sodium acrylate) and acrylamide were synthesized by free radical polymerization. The copolymer hydrogel was studied for capture of copper ion from aqueous solution. Effects of macromolecular structure (i.e., content of the acrylic acid, the quantity of the carboxyl groups neutralized with sodium hydroxide, and the degree of cross-linking) on water-sorption and copper ion uptake were investigated. With an increase in the content of acrylic acid (sodium acrylate), the copper sulfate uptake increases, and water sorption decreases quickly and then slowly increases when the acrylic acid content is high enough. The copper ion uptake is accompanied with a release of sodium ions from the copolymer. Increasing the percentage of the carboxyl groups neutralized by sodium hydroxide will increase the uptake of copper sulfate and water. With an increase in the content of the cross-linking agent, both copper sulfate uptake and water sorption decrease. Even though valence of copper ion is two times that of sodium ion, the copper ions sorption and sodium ions release do not follow a simple ion exchange relation because of insertion of acrylamide co-monomers in macromolecular chain. When copper ions interact with carboxyl groups in the copolymer to form chelating complexes, the water sorption decreases substantially. An analysis of adsorption isotherm indicates that at relatively low concentrations of CuSO4 in water, the copper ion sorption into the copolymer follows the Langmuir model. The wide angle X-ray diffraction (WAXD) data reveal that the copper sulfate sorbed in the hydrogel is not in crystalline state.
9

Fate of estrogenic compounds in agricultural soils and development of an immunoassay for their environmental detection

Caron, Emmanuelle 24 June 2011 (has links)
Estrogens produced by livestock can be released into soils when their manure is spread onto agricultural land. This is the first study to determine the sorption of a range of estrogens in a wide range of soils at the regional scale, including the sorption of the phytoestrogen equol which had never been previously studied. Sorption increased in the order of 17β-estradiol=estriol <estrone<equol in surface soils collected from 41 agricultural fields in Alberta and was significantly positively correlated with soil organic carbon content (SOC) for all estrogens. 17β-estradiol was further investigated and its mineralization in non-amended and manure-amended soils never exceeded 30% at 90 days, which suggest that even under optimum environmental conditions for mineralization, 17β-estradiol or its metabolites estrone and/or estriol appear to have a relatively long persistence in Alberta soils. Maximum 17β-estradiol mineralization was significantly positively correlated with sorption and hence increased in soils with greater SOC such as those used in this study with a long-term history of solid beef manure applications. Two ELISAs were developed using rabbit polyclonal antibodies for future field experiments and environmental monitoring. Of these, a developed 17β-estradiol+estrone+estriol ELISA could detect estriol in water from an edge of field experiment at concentrations as low as 1 ng mL-1.
10

Fate of estrogenic compounds in agricultural soils and development of an immunoassay for their environmental detection

Caron, Emmanuelle 24 June 2011 (has links)
Estrogens produced by livestock can be released into soils when their manure is spread onto agricultural land. This is the first study to determine the sorption of a range of estrogens in a wide range of soils at the regional scale, including the sorption of the phytoestrogen equol which had never been previously studied. Sorption increased in the order of 17β-estradiol=estriol <estrone<equol in surface soils collected from 41 agricultural fields in Alberta and was significantly positively correlated with soil organic carbon content (SOC) for all estrogens. 17β-estradiol was further investigated and its mineralization in non-amended and manure-amended soils never exceeded 30% at 90 days, which suggest that even under optimum environmental conditions for mineralization, 17β-estradiol or its metabolites estrone and/or estriol appear to have a relatively long persistence in Alberta soils. Maximum 17β-estradiol mineralization was significantly positively correlated with sorption and hence increased in soils with greater SOC such as those used in this study with a long-term history of solid beef manure applications. Two ELISAs were developed using rabbit polyclonal antibodies for future field experiments and environmental monitoring. Of these, a developed 17β-estradiol+estrone+estriol ELISA could detect estriol in water from an edge of field experiment at concentrations as low as 1 ng mL-1.

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