The overall goal of this study is to evaluate the ability of novel nanostructured adsorbent media (NTAs, iron sulfides (FeS2 and FeS)) to remove arsenic, selenium and mercury from ash and scrubber pond effluents. The NTAs aim to enhance arsenic removal from solution compared to conventional adsorbents. The iron sulfides are expected to produce stable residuals for ultimate disposal after removing As, Se and Hg from solution, so that removal of these compounds from wastewaters will not result in contamination of soils and groundwaters. Methods for reliably and economically producing these materials were developed. The synthesized NTAs and iron sulfides were characterized by surface analysis techniques such as XRD, FT-IR, SEM-EDS, TEM, XPS, AFM and N2-adsorption. These analyses indicated that Ti(25)-SBA-15 has highly ordered hexagonal mesopores, MT has interparticle mesopores, pyrite (FeS2) forms crystalline, nonporous rectangular nanoparticles (<500 nm), and mackinawite (FeS) forms amorphous, nonporous nanoparticles (<100 nm). Kinetic and equilibrium tests for As(III, V) removal were conducted with NTAs over a range of pH (4, 7, 9.5). The rates of arsenic uptake were very fast and followed a bi-phasic sorption pattern, where sorption was fast for the first 10 minutes, and then slowed and was almost completed within 200 minutes. Distinct sorption maxima for As(III) removal were observed between pH 7 and pH 9.5 for MT and between pH 4 and pH 7 for Ti(25)-SBA-15. The amount of As(V) adsorbed generally decreased as pH increased. In addition, a surface complexation model (SCM) based on the diffuse layer model (DLM) was used to predict arsenic adsorption envelopes by NTAs under various environmental conditions. The SCM for As(III, V) adsorption by NTAs demonstrated the role of mono- and bidentate surface complexes in arsenic adsorption. A batch reactor system was employed in an anaerobic chamber to conduct experiments to characterize both the removal of As, Se, Hg from solution and their subsequent reactions with iron sulfides. Experiment variables for removal experiments included: contaminant valence state (As(V), As(III), Se(VI), Se(IV), Hg(II)); adsorbent/reactant type (FeS, FeS2); adsorbent/reactant concentration; pH (7, 8, 9, 10); and competing ion (SO42-) concentration (0, 1, 10 mM). Experimental variables for reaction experiments were reaction time (up to 30 days) at pH 8 and oxidation states of contaminants. In addition, the stability of iron sulfides (FeS2, FeS) combined with target compounds was investigated by measuring the ability of the target compounds to resist release to the aqueous phase after removal. These experiments showed that iron sulfides were good adsorbent/reactants for target contaminants in spite of the presence of sulfate. This was particularly true at intermediate concentrations of target compounds. The experiments also demonstrated that iron sulfides interacted with target contaminants in such a way to improve their resistance to being released back to solution as pH was changed. Therefore, this study demonstrates the ability of novel nanostructured adsorbent media to remove arsenic, selenium and mercury from ash and scrubber pond effluents and the ability of iron sulfides to produce residuals that are stable when disposed in landfills.

This study is to probe into the surface characteristics, crystalline identification and inner structural changes of the synthetic iron oxides which are synthesized from pure Fe(¢»), citrate/Fe(¢») and silicate/Fe(¢») solutions at different MRs respectively. This study is also to compare the adsorption capabilities of these synthetic iron oxides serving as the adsorptive materials in containing arsenic wastewater through adsorption experiments. By means of the XRD identification analysis, the synthetic iron oxides of pure Fe(¢») and silicate/Fe(¢») are non-crystal ferrihydrite, but the synthetic iron oxide of citrate/Fe(¢») is crystal magnetite with magnetism. By means of IR spectrum analysis and comparison with the IR spectrum of iron mineral, the FTIR spectrum of pure Fe(¢») and silicate/Fe(¢») synthetic iron oxide are similar to that of ferrihydrite; The FTIR spectrum of citrate/Fe(¢») synthetic iron oxide is similar to that of magnetite. The degree of pore volume and surface area for synthetic iron oxides are as follows: silicate/Fe(¢») > Fe(¢») > citrate/Fe(¢»). With the citrate/Fe(¢») MRs increasing, the pore volume and surface area of synthetic iron oxide will decrease. However, with the silicate/Fe(¢») MRs increasing, the pore volume and surface area of synthetic iron oxide do not make great difference. Results of kinetic adsorption experiments show that the synthetic iron oxides of citrate/Fe(¢») or silicate/Fe(¢») at different MRs will adsorb arsenic better at low pH. With the pseudo-first order and the second order kinetic adsorption model to simulate the adsorption experiment data, the results show that the simulation results are consistent with the pseudo-second order kinetic adsorption model. The equilibrium adsorption experiments show that the adsorption capacity of arsenic for synthetic iron oxides is as follows: citrate/Fe(¢») > Fe(¢») > silicate/Fe(¢»), and that the adsorption capacity will decrease with the pH increasing.

Because of As toxicity, the complexity of its chemistry, and the recent lowering of the maximum contaminant level of As in municipal drinking water, there has been considerable interest for improved methods to remove As from water. Although Al and Fe hydroxides have been extensively studied as adsorbents for As removal during water treatment, coprecipitated Al:Fe hydroxides have received only minimal attention. The theoretical and experimental feasibility of coprecipitated Al:Fe hydroxide systems were evaluated by studying their mineralogy, stability, and As adsorption and desorption behavior. The broad XRD peaks revealed that Al was substituted into the ferrihydrite structure and that this was the only major product up to about a 2:8 Al:Fe molar ratio. Gibbsite and bayerite were identified when Al content was higher. The rate of recrystallization of ferrihydrite into goethite and hematite was significantly reduced as Al substitution was increased. In general, adsorption capacity of both AsV and AsIII decreased with increase in Al:Fe molar ratio; however, similar AsV adsorption capacities were observed with Fe and Al:Fe hydroxides with Al:(Al+Fe) molar ratios < 0.20. Both AsIII and AsV adsorption isotherms were effectively described by Langmuir and Freundlich equations. Adsorption maxima of AsV on Fe and Al:Fe hydroxides were observed at pH 3 to 7, and that of AsV on Al hydroxide was observed at pH 5.2, with significant decreases in adsorption with increase and decrease in pH. Adsorption maxima of AsIII decreased by approximately 4 % for each 10 % increase in Al substitution up to 5:5 Al:Fe molar ratio. Adsorption maxima of AsIII on Fe and Al:Fe hydroxides were observed at pH 8 to 9. AsIII adsorption on Al hydroxide was negligible. Counterion Ca2+, compared to Na+, enhanced the retention of AsV, especially at pH > 7. Counterion concentration did not significantly affect AsV adsorption. Though phosphate desorbed both AsV and AsIII from all Al:Fe hydroxides, quantitative desorption was never observed. The results of this study indicate the possible utility of coprecipitated Al:Fe hydroxide in wastewater treatment. Based on adsorption/desorption behavior and stability of the Al:Fe hydroxide product, the preferred Al:Fe molar ratio was 2:8.

Colloid-borne Heavy Metals in the Drainage Gallery of an Abandoned Zn-Pb-Ag Mine (in German). The colloid inventories and the colloid-borne heavy metals in the Rothschönberger Stolln adit, the main drainage gallery of the Freiberg, Germany, mining district, were investigated. This adit runs from Freiberg to the village of Rothschönberg, where it flows into the river Triebisch, a tributary of the river Elbe. The water of the adit is a typical mine water from a flooded ore mine. The main reason for choosing the Rothschönberger Stolln adit for colloid investigations was that ample knowledge concerning the origin of the water and the geology of its catchment area exists. The aim was to characterize the colloids at the mouth of the adit and to elucidate if important contaminants occur in a colloid-borne form. A colloid concentration of about 1 mg/L was found. The particles have a size of 50 to 150 nm. They primarily consist of iron and aluminum oxyhydroxide and carry trace elements such as Pb, As, Cu, Y, La. The contaminants Pb and As are almost entirely colloid-borne. Colloids can have both a retarding and a stimulating influence on the transport of contaminants. The existence of colloids should be taken into account if mine waters flow to the biosphere or if mine waters are to be purified by permeable reactive barriers.

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2007. / Title from title page screen (viewed on Sept. 18, 2008). Thesis advisor: C. Neal Stewart, Jr. Vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 153-173). Also available online.

Thèse doctorat : Sciences et Techniques du Déchet : Villeurbanne, INSA : 2004. / Titre provenant de l'écran-titre. Bibliogr. p. 168-182.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "December 2008." Includes bibliographical references (leaves 57-59). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Chicago. / "Reprinted from the Journal of the American Chemical Society, Vol. XLIII. No. 1. January 1921." Includes Abstract. Includes bibliographical references. Also available on the Internet.

Capillary-based analytical methodologies were developed to meet the need for metabolite determination in two major areas. The first area is the determination of free bilirubin in sera for the management of jaundiced neonates under critical conditions. Three sensitive detection techniques were investigated, Quantum dots (QD) mediated fluorescence, Chemiluminescence (CL) and Microelectrode detection. Four different types of QDs were synthesized for the direct bilirubin determination. The CAH-capped CdTe QDs were selected as it shows the best performance compared to organic dyes and other QDs. Its optimized preparation conditions are: refluxing solution containing Cd/Te/CAH (1:0.5:2.4 w/w) for 4 hours at 100 °C. From Transmission Electron Microscope characterization, nano-size QDs with an uniform size distribution, high luminescence and good stability were obtained. The optimized detection conditions were: incubation of bilirubin with CAH-capped CdTe QDs (5 10-6 mol/L) in water at pH=5.6 and 20 oC for 8 min prior to spectrofluorometric determination (λex=473 nm and λem=580 nm). A linear working range from 0.043-0.86 μg/mL with 0.9943 correlation coefficient and 2 ng/mL detection limit (LOD, S/N=3) were achieved. Results from nFIA-CL indicate a quick response within seconds though a poorer LOD (S/N=3) of 15 μg/mL for the direct bilirubin determination. The third technique investigated used an enzyme microelectrode and it was found to be able to couple with capillary electrophoresis (CE) in frontal analysis (FA) for the determination of free bilirubin in serum samples. Making use of the micron size of the carbon-fiber electrode, a new MCNTs (Multi-wall Carbon Nanotubes) modified CFMEs (Carbon fiber microelectrodes) was fabricated within a microchip-CE device with three guided channels to enable electrodes alignment. Method to immobilize bilirubin oxidase (BOD) onto the CFMEs surface by the carbodiimide chemistry achieved the highest detection sensitivity. Under optimized conditions (sample introduced by hydrodynamic injection at △H (20 cm), and a running/detection buffer (10 mM phosphate) at pH 7.4, working potential for amperometric detection at +0.8 V), a linear working range between 1-40 μg/mL and a detection limit (S/N=3) at 0.15 μg/mL for free bilirubin was achieved. The second area for metabolite determination was developing a new analytical method for the management of APL (acute promyelocytic leukemia) patients under arsenic treatment, a drug required continued monitoring. The analytical requirements include a high detection sensitivity and the capability to provide timely results for multiple drug residues. Using a 20 mM phosphate as the running buffer and 0.05mM CTAH (Cetyl-trimethyl-ammonium hydroxide) as an additive for EOF reversal, co-EOF (co-electroosmotic flow) stacking was established to enhance up to 200 times of the detection limit for arsenite. Satisfactory baseline separation for arsenite, arsenate, MMA (Methylarsonic acid) and DMA (Dimethylarsinic acid) was achieved with linear working ranges (correlation coefficients > 0.999) from 1-50 μg/mL for arsenate and DMA, 0.5-50 μg/mL for MMA as well as 0.1-50 μg/mL for arsenite. Detection limits (S/N=3, n=3) achievable for arsenate, arsenite, MMA and DMA were found to be 0.41 μg/mL, 0.01 μg/mL, 0.04 μg/mL and 0.32 μg/mL respectively at levels meeting the requirement for APL patient urine monitoring. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy