Sulphur dioxide (S02) is an atmospheric pollutant that has the ability to negatively impact on local vegetation, farming activities and human health. South Africa's coal fired power stations release this pollutant into the atmosphere during the combustion of coal. Current coal fired power stations operating in South Africa are not required to install any form of S02 removal equipment however, the new Air Quality Act to be implemented in South Africa could change this situation. The use of Fluidised Bed Technology with the addition of limestone or dolomite (sorbent) has the ability to absorb and convert S02 from a gaseous phase into a solid phase for easy disposal. The objective of this study was to evaluate potential commercial sorbent sources in South Africa that could potentially be used for the reduction of S02 released into the atmosphere during fluidised bed combustion of coal. Eight commercially mined sorbents within a two hundred kilometre radius of large economically mineable coalfields were selected. The study was divided into two parts in order to identify any possible links between the physical and chemical composition of the sorbents and their performance under fluidised bed combustion conditions. In Part 1, the chemical composition of the sorbents was determined by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analysis. The sorbents hardness property was determined by Hardgrove Grindability Index (HGI) testing. The physical structure of the sorbent was analysed by both Petrographical and Scanning Electron Microscope (SEM) analysis of the original/parent sorbents. In Part 2, S02 absorption capability by the sorbents was determined through batch tests conducted in a 1.6m high stainless steel, 10kW electrically heated Atmospheric Fluidised Bed Reactor (AFBR). Three different bed temperatures (800, 850 and 900°C) and three different particle size ranges (425-500, 600-710 and 850-lOOOllm) were tested for each of the eight sorbents. The highest Maximum Sulphur Retention for all of the sorbents was found to occur at a temperature of 850°C and at the smallest particle size tested, 425-500llm. The best desulphurisation sorbent of the eight sorbents tested was found to be Sorb1 with a S02 Maximum Sulphur Retention of 92.30% and a Removal Efficiency of 84.54%. Additional tests were also performed on the sorbents to get a better understanding of their desulphurisation ability. For the area calculation on the performance test graphs, it was found that the sorbent that produced the best S02 removal efficiency was not necessarily the sorbent that had the highest maximum sulphur retention. For varying quantities of sorbent added to the AFBR, it was found that each sorbent had an optimum quantity that produced the best removal efficiency. However, for desulphurisation beyond certain limits any further increase in the amount of sorbent added to the AFBR resulted only in a marginal increase in the sorbent's S02 removal. The calcium and magnesium composition of the sorbents was found to have no noticeable influence on the sorbents ability to reduce S02. The silica and inherent moisture content of the sorbent showed signs whereby an increase in their compositions produced an increase in desulphurisation. The Hardgrove Grindability Index of the sorbents indicated that the softer the sorbent, the better the S02 reduction. The petrographical analysis performed on the eight sorbents showed no obvious reason for the difference between the sorbents ability to remove S02. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.

by Chan Shuk Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 138-149). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Contents --- p.vi / List of figures --- p.xi / List of plates --- p.xiv / List of tables --- p.xv / Abbreviations --- p.xvi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Pentachlorophenol --- p.1 / Chapter 1.1.1 --- Characteristics of pentachlorophenol --- p.1 / Chapter 1.1.2 --- Application of pentachlorophenol --- p.4 / Chapter 1.1.3 --- The fate of pentachlorophenol in environment --- p.5 / Chapter 1.1.4 --- The toxicity of pentachlorophenol --- p.9 / Chapter 1.1.5 --- Remediation of pentachlorophenol --- p.13 / Chapter 1.1.5.1 --- Physical treatment / Chapter 1.1.5.2 --- Chemical treatment / Chapter 1.1.5.3 --- Biological treatment / Chapter 1.1.5.4 --- Alternative for combining two treatments / Chapter 1.2 --- Biosorbents --- p.18 / Chapter 1.2.1 --- Chitin and chitosan --- p.21 / Chapter 1.2.1.1 --- History of chitin and chitosan --- p.21 / Chapter 1.2.1.2 --- Structures of chitin and chitosan --- p.21 / Chapter 1.2.1.3 --- Sources of chitin and chitosan --- p.23 / Chapter 1.2.1.4 --- Application of chitin and chitosan --- p.26 / Chapter 1.2.1.5 --- Study on PCP removal by chitinous material --- p.28 / Chapter 1.2.2 --- Factors affecting biosorption --- p.29 / Chapter 1.2.2.1 --- Solution pH --- p.29 / Chapter 1.2.2.2 --- Concentration of biosorbent --- p.30 / Chapter 1.2.2.3 --- Retention time --- p.31 / Chapter 1.2.2.4 --- Temperature --- p.32 / Chapter 1.2.2.5 --- Agitation rate --- p.32 / Chapter 1.2.2.6 --- Initial sorbate concentration --- p.33 / Chapter 1.2.3 --- Modeling of biosorption --- p.33 / Chapter 1.2.3.1 --- Langmuir adsorption model --- p.34 / Chapter 1.2.3.2 --- Freundlich adsorption model --- p.34 / Chapter 1.3 --- Photocatalytic degradation --- p.35 / Chapter 1.3.1 --- Titanium dioxide --- p.36 / Chapter 1.3.2 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.36 / Chapter 1.3.3 --- Advantages of photocatalytic oxidation with Ti02 and H2O2 --- p.41 / Chapter 1.3.4 --- Degradation of PCP by photocatalytic oxidation --- p.41 / Chapter 2. --- Objectives --- p.45 / Chapter 3. --- Materials and methods --- p.46 / Chapter 3.1 --- Biosorbents --- p.46 / Chapter 3.1.1 --- Production of biosorbents --- p.46 / Chapter 3.1.2 --- Scanning electron microscope of biosorbents --- p.48 / Chapter 3.1.3 --- Pretreatment of biosorbents --- p.48 / Chapter 3.2 --- Pentachlorophenol preparation --- p.48 / Chapter 3.3 --- Batch biosorption experiment --- p.48 / Chapter 3.3.1 --- Quantification of pentachlorophenol by HPLC --- p.51 / Chapter 3.3.2 --- Data analysis for biosorption --- p.51 / Chapter 3.3.3 --- Selection of optimal conditions for batch PCP adsorption --- p.52 / Chapter 3.3.3.1 --- Effect of initial pH and biosorbent concentration --- p.52 / Chapter 3.3.3.2 --- Improvement on pH effect and biosorbent concentration --- p.52 / Chapter 3.3.3.3 --- Effect of temperature --- p.53 / Chapter 3.3.3.4 --- Effect of agitation rate --- p.53 / Chapter 3.3.4 --- Effect of initial PCP concentration and biosorbent concentration --- p.53 / Chapter 3.3.4.1 --- Adsorption isotherm --- p.54 / Chapter 3.4 --- Photocatalytic oxidation --- p.54 / Chapter 3.4.1 --- Reaction mixture solution --- p.54 / Chapter 3.4.2 --- Photocatalytic reactor --- p.55 / Chapter 3.4.3 --- Batch photocatalytic oxidation system --- p.55 / Chapter 3.4.4 --- Selection of extraction solvent --- p.59 / Chapter 3.4.5 --- Extraction efficiency --- p.59 / Chapter 3.4.6 --- Data analysis for PCO --- p.60 / Chapter 3.4.7 --- Irradiation time --- p.60 / Chapter 3.4.8 --- Determination of hydrogen peroxide concentration --- p.61 / Chapter 3.4.9 --- Effect of biosorbent concentration in PCO --- p.61 / Chapter 3.4.10 --- Effect of PCP amount on biosorbent in PCO --- p.61 / Chapter 3.4.11 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.62 / Chapter 3.4.12 --- Identification the intermediates of PCP degradation by PCO --- p.62 / Chapter 3.4.13 --- Evaluation of the change of PCO treated biosorbents --- p.63 / Chapter 3.4.13.1 --- Chitin assay --- p.64 / Chapter 3.4.13.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.64 / Chapter 3.4.13.3 --- Protein assay --- p.66 / Chapter 3.4.13.4 --- Biosorption efficiency --- p.66 / Chapter 3.4.14 --- Multiple biosorption and PCO cycles of PCP --- p.66 / Chapter 3.4.15 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1 --- Batch biosorption experiment --- p.68 / Chapter 4.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.68 / Chapter 4.1.1.1 --- Effect of initial pH and biosorbent concentration --- p.68 / Chapter 4.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.73 / Chapter 4.1.1.3 --- Effect of temperature --- p.73 / Chapter 4.1.1.4 --- Effect of agitation rate --- p.73 / Chapter 4.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.81 / Chapter 4.1.2.1 --- Adsorption isotherm --- p.82 / Chapter 4.2 --- Photocatalytic oxidation --- p.88 / Chapter 4.2.1 --- Selection of extraction solvent --- p.88 / Chapter 4.2.2 --- Determination of hydrogen peroxide concentration --- p.88 / Chapter 4.2.3 --- Effect of biosorbent concentration in PCO --- p.88 / Chapter 4.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.94 / Chapter 4.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.98 / Chapter 4.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.102 / Chapter 4.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.102 / Chapter 4.2.7.1 --- Chitin assay --- p.102 / Chapter 4.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.102 / Chapter 4.2.7.3 --- Protein assay --- p.102 / Chapter 4.2.7.4 --- Biosorption efficiency --- p.109 / Chapter 4.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.109 / Chapter 4.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.109 / Chapter 5. --- Discussion --- p.115 / Chapter 5.1 --- Batch biosorption experiment --- p.115 / Chapter 5.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.115 / Chapter 5.1.1.1 --- Effect of initial pH --- p.115 / Chapter 5.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.118 / Chapter 5.1.1.3 --- Retention time --- p.119 / Chapter 5.1.1.4 --- Effect of temperature --- p.120 / Chapter 5.1.1.5 --- Effect of agitation rate --- p.121 / Chapter 5.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.121 / Chapter 5.1.2.1 --- Modeling of biosorption --- p.122 / Chapter 5.2 --- Photocatalytic oxidation --- p.123 / Chapter 5.2.1 --- Selection of extraction solvent --- p.124 / Chapter 5.2.2 --- Determination of hydrogen peroxide concentration --- p.124 / Chapter 5.2.3 --- Effect of biosorbent concentration in PCO --- p.125 / Chapter 5.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.127 / Chapter 5.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.127 / Chapter 5.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.128 / Chapter 5.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.128 / Chapter 5.2.7.1 --- Chitin assay --- p.129 / Chapter 5.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.129 / Chapter 5.2.7.3 --- Protein assay --- p.131 / Chapter 5.2.7.4 --- Biosorption efficiency --- p.131 / Chapter 5.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.132 / Chapter 5.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.132 / Chapter 6. --- Conclusion --- p.134 / Chapter 7. --- Recommendation --- p.137 / Chapter 8. --- References --- p.138

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Sample preparation is a key step in chemical analysis, and includes isolation of target analytes, removal of interferences, preconcentration, and/or modification of target analytes (if needed). Sample preparation is also the most time-consuming and error-prone step in the whole analytical process. Traditional sample preparation techniques involve hazardous solvents. Considering the environmental and health safety, it is desirable to reduce or eliminate organic solvents in sample preparation. Solid phase microextraction (SPME) was introduced as a solvent free sample preparation technique. Capillary microextraction (CME) is one of the formats of SPME that can be easily coupled to high performance liquid chromatography (HPLC). In SPME and CME a solvent free sample preparation is accomplished by using a sorbent coating instead of hazardous organic solvents commonly used in conventional extraction techniques. This research is focused on the development and systematic examination of novel niobia-, titania- and silica-based organic-inorganic hybrid sol-gel sorbents for CME. Conventionally silica and titania based precursors were used in organi-inorganic hybrid sol-gel sorbents for CME, here novel niobia based precursor was used in creating organic-inorganic hybrid sol-gel sorbents. Poly tetrahydrofuran (polyTHF) as well as electrically neutral and charged organic ligands were used to prepare the sorbents for CME coupled to HPLC. Characterization of created sol-gel sorbents, evaluation of extraction performance, and enrichment of environmentally and biomedically important analytes including organophosphorus compounds were performed. CME performances of the created sorbents were characterized by specific extraction (SE) (a measure of extraction efficiency) and desorption efficiency (DE) (a measure of completeness desorption of extracted analytes). Scientific findings of this research has shown that sol-gel niobia-polyTHF sorbent provides 60 to 70 % higher SE values for different environmentally important analytes compared to analogously prepared silica-polyTHF sorbent. This superior extraction performance can be attributed to the presence of surface Lewis acid sites undergoing Lewis acid-base interactions with analytes representing Lewis bases. The prepared sorbents also have the ability to undergo van der Waals interactions due to the presence of polyTHF. Absence of Lewis acid sites on silica surface resulted in inferior extraction efficiency compared to niobia-polyTHF sorbents. Extraction efficiency of the created sol-gel based niobia-polyTHF was also explored in the enrichment of organophosphorus pesticides and compared with that of the state-of-the-art titania-based sorbent. Sol-gel niobia-polyTHF sorbent has provided 40 to 50 % higher SE values in the enrichment of organophosphorus pesticides compared to sol-gel titania-polyTHF sorbent which can be attributed to the presence of bronsted acid sites on niobia surface (but lacking on titania) along with Lewis acid sites. To explore relative contributions of electrostatic, Lewis acid-base and van der Waals interactions between sol-gel sorbents and analytes, two sol-gel sorbents, one containing a positively charged octadecyl ligand and the other a neutral octadecyl ligand were created. Positive charge was imparted by using N-octadecyldimethyl [3-(trimethoxysilyl) propyl] ammonium chloride (C18 (+ve)) as ligand bearing co-precursor. Similarly N-octadecyl trimethoxysilane was used to impart a neutral C18 ligand in sol-gel coating. Experimental results have shown that sol-gel Nb2O5-C18 (+ve) sorbent has superior extraction efficiency compared to sol-gel based Nb2O5-C18 and purely inorganic Nb2O5 sorbents in enrichment of organophosphorus compounds (nucleotides and organophosphorus pesticides). Electrostatic interactions between the positive charge of organic ligand (C18 (+ve)) and negative charge of phosphate group has contributed to the higher extraction performance of sol-gel based Nb2O5-C18 (+ve) sorbent. TiO2-C18 (+ve) sorbent was also created to compare with the novel sol-gel niobia based sorbents, since titania-based sorbents are considered as the state-of-the-art extraction material in the enrichment of organophosphorus compounds. Established research results has shown that sol-gel based Nb2O5-C18 (+ve) sorbent has provided 40 to 50 % higher specific extraction values for organophosphorus compounds compared to sol-gel based TiO2-C18 (+ve) sorbent. Desorption efficiency of sol-gel Nb2O5-C18 (+ve) and TiO2-C18 (+ve) sorbents were 96% vs 90%. This superior DE of sol-gel Nb2O5-C18 (+ve) sorbent can be attributed the higher Lewis acid strength of titania than nioiba. The developed sol-gel niobia based sorbents have also shown high pH stability compared to traditional sol-gel silica based sorbents. The created sol-gel sorbents were characterized by less than 5% run to run RSD values and also less than 5% capillary to capillary RSD values which indicated the high reproducibility of developed method. The developed sol-gel niobia sorbents are applicable to sample preparation in different fields including biomedical, environmental, forensic, defense etc.

No description available.

Different types of biomass samples including fungi and algae were treated for their gold and cobalt uptake capacity. The performance of activated carbon and ion-exchange resins were compared with the metal uptake capacity of the biosorbents. Sargassum natans, a brown seaweed, exhibited a high gold uptake capacity outperforming the ion-exchange resin and equalling activated carbon. Algal biomass of Ascophyllum nodosum proved to be a very potent biosorbent for cobalt. While the temperature, agitation and biomass particle size did not affect the metal uptake process, the effect of pH was significant for both gold and cobalt uptakes. The optimum pH for gold uptake was 2.5 and for cobalt, was 4-5. The kinetics of cobalt biosorption was relatively rapid (5 min) at the initial concentration of the metal in solution, 100 mg/L. The biosorptive uptake of gold required 2 h to reach equilibrium when the initial concentration of gold was 100 mg/L. None of the tested cations, such as K$ sp+$, Ca$ sp{2+}$, Fe$ sp{2+}$, Cr$ sp{3+}$, UO$ sbsp{2}{2+}$, Ni$ sp{2+}$, Zn$ sp{2+}$, Ag$ sp+$, affected the gold uptake capacity of S. natans biomass under the optimum conditions. Anions, such as NO$ sbsp{3}{-}$, SO$ sbsp{4}{2-}$, CO$ sbsp{3}{2-}$, PO$ sbsp{4}{3-}$, and Pb$ sp{2+}$ suppressed the gold uptake somewhat. Under the optimum process conditions cations, except K$ sp+$ and Fe$ sp{2+}$, and anions, NO$ sbsp{3}{-}$ in particular, exhibited a pronounced negative effect on the cobalt uptake by A. nodosum biomass. / Sequestered gold was eluted with a mixture of thiourea and ferric ammonium sulphate solution. Approximately 98% of sequestered gold was eluted with 17 h in a batch contacting system at the optimum solids (biomass)-to-liquid ratio of 5 and pH of 5. At increased temperatures, the gold elution rate increased only slightly. Efficient desorption of cobalt was achieved using CaCl$ sb2$/HCL solution at pH 3. Cobalt elution time was quite short. Temperature affected neither desorption rate nor the equilibrium. The optimum solid-to-liquid ratio was 12 for desorption of cobalt from A. nodosum biomass. / The gold taken up by the biosorbent was deposited in its elemental form. / Available mathematical models, including the REDEQL2 chemical equilibrium model, were tested for theoretical predictions of co-ion competition in attempt to better understand the biosorption mechanism. (Abstract shortened with permission of author.)

Thesis (M.S.)--Ohio University, June, 1999. / Title from PDF t.p.

Thesis (Ph. D.)--Ohio University, November, 1999. / Title from PDF t.p.

This thesis presents solid phase extraction (SPE) methodologies based on mixed-mode polymeric sorbents; a mixed mode strong anion exchanger (Agilent SampliQ SAX) and a mixed mode strong cation exchanger (Agilent SampliQ SCX). Furthermore, dispersive-SPE based on a quick, easy, cheap, effective, rugged and safe (QuEChERS) method was assessed for applicability in the determination of drug residues. The mixed-mode polymeric sorbents were evaluated for the simultaneous fractionation of drugs that exhibit diverse polarities with acidic, basic and neutral functionalities in biological matrices (plasma and urine). The polymeric skeleton of these sorbents entails an exchanger group and therefore provides two retention mechanisms, strong cation or anion exchange retention mechanisms with hydrophobic interactions. It was demonstrated that with a sequential elution protocol for sample clean-up analytes were fractionated into acidic, basic and neutral classes. The SAX was employed for analysis of ketoprofen, naproxen (acidic drugs), nortriptyline (basic) and secobarbital (neutral) from urine sample. The SCX was used for fractionating phenobarbital, p-toluamide (acidic), amphetamine, m-toluidine (basic) and acetaminophen (neutral drug) from plasma sample. QuEChERS method was employed for quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) from fish fillets and soil; 9 sulfonamides (SAs) from chicken muscles and acrylamide (AA) in cooking oil. The analyte recoveries ranged from 79.6 - 109% with RSDs ranging from 0.06 - 1.9% at three different fortification levels. Good linearity (r2 > 0.9990) was attained for most analytes. The limits of detection and quantification ranged from 0.03 - 0.84 μg/ml and 0.81 - 1.89 μg/ml respectively for analytes in biological samples. LODs and LOQs for analytes in food and environmental samples ranged from 0.02 to 0.39 and 0.25 to 1.30 ng/g respectively.

The thesis presents the evaluation of polysulfone sorbents for solid phase extraction (SPE) and the development of colorimetric probes for pesticides analysis in water. Through electrospraying and electrospinning techniques, different morphologies of sorbents (particles, beaded fibers and bead-free fibers) were fabricated. The sorbents were morphologically characterized by scanning electron microscopy. Adsorption capacities of sorbents were evaluated by conducting recoveries studies for model pesticides; atrazine, chlorpyrifos and DDT using batch and column SPE modes. Better recovery results were achieved by employing the batch mode of fibers, as values ranged from 98 to 105percent. Further sorbent evaluation was conducted using breakthrough experiments and static experiments. The breakthrough studies indicated that 1700 μL was the sample volume that could be percolated with no breakthrough of the analyte that correspond to a concentration of 150 mg/g of sorbent that can be extracted without any loss of analyte. From static studies, quantities of each model compound adsorbed into the fiber at the equilibrium time were evaluated. The adsorbed atrazine was 65, chlorpyrifos 250 and DDT 400 mg/g of sorbent. Kinetic studies suggested retention mechanism following pseudo first and second order model observed by high correlation coefficients (> 0. 96), demonstrating the fiber affinity to retain both polar and non-polar compounds opening a possibility to be used as sorbent for sample preparation of different classes of pesticides in water. For the second part of the study simple strategies for colorimetric sensing based on silver nanoparticles and polivinylpyrrolidone capped nanoparticles were developed, respectively for atrazine and chlorpyrifos detection. The limits of detection of the methods were 3.32 and 0.88 mg/L for atrazine and chlorpyrifos respectively. The applicability of the probe in real samples was demonstrated by the recoveries studies of tap water varying from 94 to 104 percent. The versatility of the probe was demonstrated by affording a simple, rapid and selective detection of atrazine and chlorpyrifos in the presence of other pesticides by direct analysis without employing any sample handling steps. Attempt to incorporate the probes in a solid support was achieved by using nylon 6 as solid support polymer proving to be fast and useful for on-site detection.