A study has been conducted for the qualitative and Quantitative analysis of chlorinated organic compounds in water. The study included the adaptation of Amberlite XAD macroreticular resin techniques for the concentration of municipal wastewater samples, followed by GC/MS analysis. A new analytical method was developed for the determination of volatile halogenated organics using liquid-liquid extraction and electron capture gas chromatography. And, a computer program was written which searches raw GC/MS computer files for halogen-containing organic compounds.

Graphitic carbon nitride (g-C3N4) heterojunction composites with the semiconducting metal oxides, CeO2, ZnO and TiO2 are prepared in situ by co-calcination of the precursor materials or by a solvothermal method. The structural, morphological and the optical properties of the prepared materials are studied using various microscopy and spectroscopy techniques. The synthesized composite materials, CeO2/g-C3N4, ZnO/g-C3N4 and TiO2/g-C3N4 are more efficient in the photocatalytic degradation of the water pollutants indigo carmine (IC) and atrazine than the pure metal oxide, g-C3N4, or their physical mixtures. The CeO2/g-C3N4 and ZnO/g-C3N4 composites also exhibit improved degradation efficiencies of atrazine as compared to the individual metal oxide or g-C3N4 materials. The improved photocatalytic activity of the composites are attributed to the effective electron-hole charge separation within composite heterojunction, resulting from the well matched energy levels of the metal oxide and g-C3N4. This strategy could be helpful for the synthesis of other metal oxide and g-C3N4 composites for photocatalytic applications.

The necessity of cost effective, environmentally friendly technology has become increasingly important to remediate persistent organic pollutants in the environment. The emerging greener ultrasound technology has the potential to serve the remediation industry. In this study, the use of low power, high frequency (HF) ultrasound (1.6 MHz, 145 W/L) has been shown to effectively remediate DDT (90% of 8 mg/L) in water and sand slurries. Addition of iron powder accelerated DDT degradation in the sand slurry under ultrasonication. The potential of HF ultrasound (1.6 MHz, 160 W/L) in degradation of the non-volatile, polar model compound methylene blue (MB) was studied in MB spiked demineralised water and wastewater. A 70 % of 0.4 mg/L of MB was degraded in demineralised water whereas only 54% of MB degraded in MB spiked wastewater. There was a decrease in MB degradation rate with an increase in MB concentration. High power, low frequency (LF) ultrasound (20 kHz, 932 W/L) was used to desorb 400 mg/L of DDT added to three different natural soil slurries at 5, 10, 15 and 20 wt. % each. Each soil slurry was prepared in 0.1% v/v SDS surfactant solution, soaked for 30 min. and heated for another 30 min. at 40 oC before sonication. For the neutral pH soil slurry with higher dissolved organic carbon, the desorption efficiency achieved was over 80% in 30 s sonication. Alkaline soil with higher surface area than neutral soil indicated 60% desorption efficiency while the acidic soil, with the highest surface area and a higher amount of non-soluble organic matter, yielded 30% desorption efficiency under similar desorption conditions. Coconut fibre, used to biosorb the desorbed DDT in the decanted solution, was found to have over 25 g/kg of biosorption capacity for DDT. The surfactant SDS and associated DDT were completely separated from decanted liquid of the desorbed slurry with alum using adsorptive micellar flocculation in 60 min. settling. Acidic pH and molar concentration ratio of Al3+/SDS = 0.5 was used to completely remove the DDT. Using 20 kHz, 1125 W/L of sonication in an 80 mL reactor with air saturated 50 mg/L DDT at 20oC, the DDT removal efficiency achieved was 80% in 20 min. With zero valent iron addition, DDT removal efficiency in 15 min. is 100% with 15 and 22 mg/L of initial DDT concentrations. The settled DDT slurrywas remediated using 20 kHz at 240 W/L achieving DDT removal efficiency of 87% in 15 min. Also LF ultrasound was found to be effective in remediating chloroform (8 mg/L in 60 min) from spiked demineralised water and contaminated groundwater in both batch (120 W/L) and flow cell (6000 W/L) modes. Modeling and simulation of the ultrasonic reactor under 20 kHz ultrasonication was performed for various shape reactors using commercially available software. For almost all reactors, the highest ultrasonic intensity was observed near the transducer???s vibrating area. It was found that the highest acoustic pressure distribution, which is critical to the performance of the reactor, occurred in the conical reactor and flow cell configuration. / Thesis (PhD)--University of South Australia, 2010

Durante la última década se han publicado un gran número de estudios de investigación sobre la ubicuidad de diferentes contaminantes orgánicos en todo tipo de matrices ambientales, principalmente en agua. Entre éstos, la presencia medioambiental de fármacos y en concreto de antibióticos ha sido investigada con especial interés, debido a sus altas tasas de consumo y elevada actividad biológica (promoción de resistencia bacteriana). A este deterioro de la calidad de los recursos hídricos se une además el problema de su escasez, sobre todo en las cuencas mediterráneas, de modo que la reutilización del agua se hace imprescindible. Sin embargo, la falta de eficacia de los sistemas convencionales de tratamiento de aguas residuales para eliminar estos contaminantes orgánicos pone de manifiesto su entrada continuada en las aguas superficiales receptoras mediante los efluentes de las depuradoras, y el riesgo que supondría esta reutilización. Así pues, queda patente la necesidad de disponer de información nueva y valiosa sobre la presencia medioambiental de las sulfamidas, familia de antibióticos de alto consumo y cuya presencia medioambiental tiene origen en un uso principalmente veterinario y agrícola, (sulfametazina, sulfadimetoxina), pero también humano (sulfametoxazol, sulfapiridina). Para ello, es necesario el desarrollo de diversas herramientas analíticas avanzadas que nos permitieran la determinación de esta familia de antibióticos en diferentes matrices de agua ambiental, así como en fango de depuradora y suelo agrícola. Con las diferentes metodologías analíticas se pretende evaluar la presencia y persistencia de estos antibióticos y de sus metabolitos mayoritarios en los diferentes ecosistemas acuáticos, evaluando la eficacia de las técnicas de tratamiento de aguas residuales convencionales aplicadas en la actualidad en diferentes EDARs, y también de varias alternativas como los bioreactores de membrana o los bioreactores de lecho fijo (MBR o FBBR, respectivamente). Asimismo, estudiando su biodegradabilidad y persistencia medioambiental, es posible conocer en mayor profundidad la naturaleza y comportamiento de estos compuestos. Considerando todo lo anterior, durante el desarrollo de esta Tesis nos hemos marcado como principal objetivo el desarrollo y aplicación de nuevas metodologías analíticas basadas en la cromatografía de líquidos acoplada a la espectrometría de masas para la determinación de sulfamidas y sus metabolitos acetilados en aguas (residuales, superficiales, subterráneas) y matrices sólidas (fangos de depuradora y suelos agrícolas). Durante el análisis de aguas residuales, se evaluó también la eliminación de estos compuestos durante el tratamiento en las diferentes depuradoras, comparando la eficacia de diferentes tipos de tratamiento y su impacto en las zonas de vertido, comprendiendo así el destino de estos antibióticos en todo el ciclo del agua. Posteriormente, estudiamos la biodegradabilidad de diferentes sulfamidas mediante el tratamiento con hongos en medio líquido y sólido, y se llevó a cabo la identificación de los productos de transformación derivados mediante cromatografía de líquidos de ultra-alta resolución-espectrometría de masas en tándem con un sistema híbrido cuadrupolo tiempo de vuelo (UHPLC-QqTOF-MS/MS). También realizamos un estudio de destino de las sulfamidas, evaluando la fotodegradación de algunas de ellas y sus metabolitos acetilados en diferentes matrices acuosas, considerando también la aparición e identificación de los productos de fototransformación que se generan durante su fotólisis mediante UHPLC-QqTOF-MS/MS. Por último, mencionar que con los datos de presencia medioambiental obtenidos se llevó a cabo la evaluación del impacto medioambiental de las sulfamidas detectadas en los diferentes tipos de agua estudiados, estimando los coeficientes de riesgo asociados siguiendo las directrices marcadas por la Agencia Europea del Medicamento (EMEA). / Sulfonamides (SAs) are one of the most widely used antibiotics in human and especially in animal husbandry. So far, concern regarding the environmental presence of sulfonamides and other species of antibiotics has focused mainly on the potential spread of antimicrobial resistance. However, their biological activity and high resistance to biodegradation may lead to long residence times in both water and soil matrices. Long-term ecological risks and unpredicted effects can result from unintentional exposure of different organisms and even human health could be negatively affected. In this context, this PhD thesis aimed to study the environmental occurrence of the most relevant sulfonamides in all types of waters, sewage sludge and agricultural soils. In order to fully understand the fate and effects of this family of antimicrobials in the environment, further research on their resiliance and biodegradability has been carried out. The need of developing new advanced analytical methodologies, fast, robust and with high sensitivity for the analysis of sulfonamides and their acetylated metabolites at environmental levels was the first and one of the main objectives of this PhD Thesis. These analytical methodologies were succesfully applied for the analysis of real samples in different monitoring studies in wastewater treatment plants, rivers and aquifers. Sulfonamides and their acetylated metabolites were ubiquitous in all the water samples studied, with levels ranging from the low pg L-1 to μg L-1 (mainly in wastewater influents, but also in some surface water samples from the Llobregat River). Maximum levels detected in sewage sludge were up to 139.2 ng g-1 (sulfamethazine). The last part of the PhD focused on the biodegradability and behaviour of the sulfonamides in the environment. The efficiency of conventional wastewater treatments, usually based on activated sludge (CAS), was evaluated and removal rates were estimated for the different sulfonamides studied. The ability of white rot fungi Trametes versicolor to degrade sulfamethazine was also studied, as well as the photodegration kynetics of sulfapyridine, sulfamethazine and their respective acetylated metabolites in wastewater effluents and HPLC water under simulated irradiation.

The Suwannee River natural organic matter (SRNOM) was fractionated by preparative size-exclusion chromatography (SEC) into seven molecular weight (MW) fractions. The SRNOM and its MW fractions were subsequently analyzed for their concentrations of acidic functional groups by direct titrations, average MWs and MW distributions by semi-analytical SEC, and charge-to-MW distributions by capillary electrophoresis. Carboxyl concentrations in the MW fractions were inversely proportional to their average MWs. Conversely, the phenolic concentrations, though smaller than the carboxyl concentrations, were proportional to average MWs. Hysteresisthe non-overlap between sequential forward and reverse titrationswas observed for the SRNOM and its MW fractions, where the reverse titrations predicted a greater concentration of carboxylic acid groups than the forward titration. Because hysteresis is thought to be caused by the base-catalyzed hydrolysis of esters, this suggests that ester groups in the SRNOM are distributed over all MWs. Data for direct titrations, MW distributions, and capillary electrophoresis were evaluated by a computational scheme that solves for the most probable distribution of acidic functional groups and charges on solutes in the SRNOM and the MW fractions as a function of pH. Depending on the MW ranges of the samples, solutes in the SRNOM and the MW fractions are predicted to have from one to a maximum of 25 carboxyl groups per solute. Most phenolic groups are predicted to be on solutes that have a minimum of two carboxyl groups. At low pH, all samples have high relative abundances of solutes with the lowest charges. The charges of solutes are predicted to increase with increasing pH due to the sequential ionization of acidic functional groups. Depending on the MW ranges of the samples, the maximum probable charges of solutes in the SRNOM and the fractions at high pH are -12 to -30. By knowing the most probable distribution of charge and abundances of acidic functional groups, researchers will make better estimates of thermodynamic parameters and models that describe equilibria between metals and natural organic matter in the environment.

The necessity of cost effective, environmentally friendly technology has become increasingly important to remediate persistent organic pollutants in the environment. The emerging greener ultrasound technology has the potential to serve the remediation industry. In this study, the use of low power, high frequency (HF) ultrasound (1.6 MHz, 145 W/L) has been shown to effectively remediate DDT (90% of 8 mg/L) in water and sand slurries. Addition of iron powder accelerated DDT degradation in the sand slurry under ultrasonication. The potential of HF ultrasound (1.6 MHz, 160 W/L) in degradation of the non-volatile, polar model compound methylene blue (MB) was studied in MB spiked demineralised water and wastewater. A 70 % of 0.4 mg/L of MB was degraded in demineralised water whereas only 54% of MB degraded in MB spiked wastewater. There was a decrease in MB degradation rate with an increase in MB concentration. High power, low frequency (LF) ultrasound (20 kHz, 932 W/L) was used to desorb 400 mg/L of DDT added to three different natural soil slurries at 5, 10, 15 and 20 wt. % each. Each soil slurry was prepared in 0.1% v/v SDS surfactant solution, soaked for 30 min. and heated for another 30 min. at 40 oC before sonication. For the neutral pH soil slurry with higher dissolved organic carbon, the desorption efficiency achieved was over 80% in 30 s sonication. Alkaline soil with higher surface area than neutral soil indicated 60% desorption efficiency while the acidic soil, with the highest surface area and a higher amount of non-soluble organic matter, yielded 30% desorption efficiency under similar desorption conditions. Coconut fibre, used to biosorb the desorbed DDT in the decanted solution, was found to have over 25 g/kg of biosorption capacity for DDT. The surfactant SDS and associated DDT were completely separated from decanted liquid of the desorbed slurry with alum using adsorptive micellar flocculation in 60 min. settling. Acidic pH and molar concentration ratio of Al3+/SDS = 0.5 was used to completely remove the DDT. Using 20 kHz, 1125 W/L of sonication in an 80 mL reactor with air saturated 50 mg/L DDT at 20oC, the DDT removal efficiency achieved was 80% in 20 min. With zero valent iron addition, DDT removal efficiency in 15 min. is 100% with 15 and 22 mg/L of initial DDT concentrations. The settled DDT slurrywas remediated using 20 kHz at 240 W/L achieving DDT removal efficiency of 87% in 15 min. Also LF ultrasound was found to be effective in remediating chloroform (8 mg/L in 60 min) from spiked demineralised water and contaminated groundwater in both batch (120 W/L) and flow cell (6000 W/L) modes. Modeling and simulation of the ultrasonic reactor under 20 kHz ultrasonication was performed for various shape reactors using commercially available software. For almost all reactors, the highest ultrasonic intensity was observed near the transducer???s vibrating area. It was found that the highest acoustic pressure distribution, which is critical to the performance of the reactor, occurred in the conical reactor and flow cell configuration. / Thesis (PhD)--University of South Australia, 2010

The necessity of cost effective, environmentally friendly technology has become increasingly important to remediate persistent organic pollutants in the environment. The emerging greener ultrasound technology has the potential to serve the remediation industry. In this study, the use of low power, high frequency (HF) ultrasound (1.6 MHz, 145 W/L) has been shown to effectively remediate DDT (90% of 8 mg/L) in water and sand slurries. Addition of iron powder accelerated DDT degradation in the sand slurry under ultrasonication. The potential of HF ultrasound (1.6 MHz, 160 W/L) in degradation of the non-volatile, polar model compound methylene blue (MB) was studied in MB spiked demineralised water and wastewater. A 70 % of 0.4 mg/L of MB was degraded in demineralised water whereas only 54% of MB degraded in MB spiked wastewater. There was a decrease in MB degradation rate with an increase in MB concentration. High power, low frequency (LF) ultrasound (20 kHz, 932 W/L) was used to desorb 400 mg/L of DDT added to three different natural soil slurries at 5, 10, 15 and 20 wt. % each. Each soil slurry was prepared in 0.1% v/v SDS surfactant solution, soaked for 30 min. and heated for another 30 min. at 40 oC before sonication. For the neutral pH soil slurry with higher dissolved organic carbon, the desorption efficiency achieved was over 80% in 30 s sonication. Alkaline soil with higher surface area than neutral soil indicated 60% desorption efficiency while the acidic soil, with the highest surface area and a higher amount of non-soluble organic matter, yielded 30% desorption efficiency under similar desorption conditions. Coconut fibre, used to biosorb the desorbed DDT in the decanted solution, was found to have over 25 g/kg of biosorption capacity for DDT. The surfactant SDS and associated DDT were completely separated from decanted liquid of the desorbed slurry with alum using adsorptive micellar flocculation in 60 min. settling. Acidic pH and molar concentration ratio of Al3+/SDS = 0.5 was used to completely remove the DDT. Using 20 kHz, 1125 W/L of sonication in an 80 mL reactor with air saturated 50 mg/L DDT at 20oC, the DDT removal efficiency achieved was 80% in 20 min. With zero valent iron addition, DDT removal efficiency in 15 min. is 100% with 15 and 22 mg/L of initial DDT concentrations. The settled DDT slurrywas remediated using 20 kHz at 240 W/L achieving DDT removal efficiency of 87% in 15 min. Also LF ultrasound was found to be effective in remediating chloroform (8 mg/L in 60 min) from spiked demineralised water and contaminated groundwater in both batch (120 W/L) and flow cell (6000 W/L) modes. Modeling and simulation of the ultrasonic reactor under 20 kHz ultrasonication was performed for various shape reactors using commercially available software. For almost all reactors, the highest ultrasonic intensity was observed near the transducer???s vibrating area. It was found that the highest acoustic pressure distribution, which is critical to the performance of the reactor, occurred in the conical reactor and flow cell configuration. / Thesis (PhD)--University of South Australia, 2010

M. Tech. (Chemistry Department, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Benzene, toluene and xylene (BTX) are water pollutants that appear very often in chemical and petrochemical wastewaters due to gasoline leakage from storage tanks and pipelines. These BTX compounds can cause adverse health effects on humans even at very low concentrations. Amongst the available pollutant removal methods from wastewater, adsorption has been used due to its ease of operation, simplicity and cost-effectiveness. Different adsorbents have been used for BTX removal, however the use of Magnetite-organic acid composites as an adsorbent seems to offer a much cheaper alternative. This work seeks to develop a one-step microwave synthesis and optimization of magnetite-oleic (MNP-OA) and magnetite-palmitic (MNP-PA) acid) composites. Response surface methodology was used to optimize the magnetite-organic acid composites. The optimum conditions estimated for MNP-OA acid composite were 78.3 % Fe content, 1561.9 S/cm conductivity, 82.2, 84.1, 85.3 mg/g for BTX adsorption capacity. The MNP-PA composite were 75.6 % Fe content, 1325.66 S/cm conductivity, 60.55, 64.47, 63.06 mg/g for BTX adsorption capacity. The materials were characterized, and the adsorption process was optimized for BTX removal from aqueous solution. X-ray analysis confirmed the formation of magnetite by the presence of both ferric and ferrous ion states on the surface. It was noted that after modification, the magnetite-organic acids characteristics peaks became broad and the height of the peaks decreased indicating that surface modification with organic acid controls the crystallinity of the material. The average cystalline size of MNP, MNP-OA, and MNP-PA composites were 19.7, 17.1 and 17.9 nm. FTIR analysis confirmed the target materials were produced and also to determine if the organic acids were imobilised on the surface of the magnetite. TEM images presented that the MNP, MNP-OA, and MNP-PA composites were spherical in shape with particle average sizes of 18.4 ± 0.5, 15.6 ± 0.5 and 16.5 ± 0.5 nm. The magnetite-organic acids show the particles with better isolated as compared to that of the MNP. The BET isotherms of the materials were described by a type IV characteristic related to uniform mesoporous materials. The magnetic saturation value for MNP, MNP-OA, and MNP-PA composites were 62.9, 59.0 and 51.0 emu/g. The decrease in magnetization was explained by the presence of the non-magnetic layer on magnetite surface. The pHpzc of MNP, MNP-OA, and MNP-PA composites were 6.9, 6.4 and 6.1. The decrease in pHpzc aftern modification was due to the charging acid-base interaction mechanism of metal oxide nanoparticles. The optimum pH for the adsorption of BTX onto MNP, MNP-OA, and MNP-PA composites was determined to be pH 7 for benzene, pH 8 for toluene and xylene. Among the three pollutants, xylene had the highest adsorption capacity followed by toluene and benzene. The optimum adsorbent dose for the adsorbents for the adsorption process was 0.1 g/dm3. The effect of time on the uptake of BTX onto MNP, MNP-OA, and MNP-PA composites show that initial adsorption of BTX occured between 0 and 3 min of contact time. The effect of initial concentration results shows the initial concentration of BTX increases from 100 to 350 mg/dm3 with an increase in adsorption capacity. The results suggest that the adsorption process is controlled by concentration driving force. The experimental data was fitted to the pseudo-first and pseudo-second-order kinetic models for all adsorbents and all pollutants. The pseudo-second-order models showed good correlation as compared to the first-pseudo model. Desorption studies for benzene, toluene and xylene using the pure magnetite, magnetite-palmitic and magnetite oleic acid composites indicate adsorption mrchanism can be explained in relation to acid–base chemistry. Electron donation from the phenyl ring of each benzene, toluene and xylene compound to surface iron atoms of magnetite has been suggested. The CH3OH and H2O desorbing agents were used and regeneration using five cycles show that the percentage desorption decreses from Benzene < Toluene < Xylene. The reduction in adsorption capacity after the cycles are attributed to decomposition of the adsorbents active sites and mass loss of the sample.

Current use of alcohols as neat automotive fuels or as inexpensive octane enhancers in gasoline-alcohol blends, in addition to their uses as solvents and starting materials in manufacturing, have created a concern due to the increased potential for groundwater contamination. Adsorption and water solubility are primarily responsible for separating gasoline-alcohol blend components in soils and would allow alcohols to move ahead of the remaining gasoline components (e.g., benzene). The presence of alcohols would be difficult to detect, and levels hazardous to humans or animals could be reached readily. The primary objective of this study was to investigate the use of a ¹⁴C-tracer technique for evaluation of subsurface biodegradation of groundwater contaminants. A modification of the heterotrophic activity assay, the radiorespirometric method, was employed as the ¹⁴C-tracer technique. The microorganisms used were those present in soil sampled aseptically at locations in Pennsylvania and Virginia. Both saturated and unsaturated zone soils were used. The alcohols used were methanol and tertiary-butanol. Methanol was easily degraded under both aerobic and anoxic conditions up to approximately 3000 mg/L. Tertiary-butanol was degraded very slowly under both aerobic and anoxic/anaerobic conditions, and an inhibitory concentration was not readily apparent. Tertiary-butanol was degraded at rates approximately 10² slower than methano1. The data generated in this study compare favorably with data obtained by oxygen-uptake and static-microcosm methodologies. / Master of Science / incomplete_metadata

Natural organic matter (NOM) is a diverse blend of decomposed animal and plant material found in different natural water sources. Due to its large and complex structure, NOM is difficult to both remove and characterize in water. Therefore, there is a need to separate NOM into its components before it can be characterized. The aim of this project was to fractionate NOM through a novel size exclusion chromatography (SEC) composite (poly (styrene-divinyl benzene) (PS-DVB) and Polysilsesquioxane (PSQ)) packed column. Raw and final water samples from Mid-Vaal (MV), Olifantspoort (LO), Mtwalume (MT) and Preekstoel (P) were investigated. Poly (styrene-divinyl benzene) (PS-DVB) and polysilsesquioxane were both synthesized and optimized at various temperatures, compositions and time periods. An end-capping material such as hexamethyldisilizane (HMDS) was added on the PSQ to prevent active silanol groups on the polysilsesquioxane (PSQ) from reacting with active sites of NOM (our analyte). The E-PSQ (end-capped PSQ) and PS-DVB materials were packed in eight different SPE cartridges first, before the materials could be packed in the SEC column. This packing was done to check for the best mass composition of the E-PSQ and PS-DVB. From the obtained SPE results, both the EPSQ and PS-DVB were packed in one SEC/GPC column at a ratio of 1:1 in order to form the composite hybrid material. The packed SEC column was connected to an HPLC instrument and various column efficiency tests were evaluated. The results for the test of interactions with acidic compounds implied that the column can be used for the acidic analytes such as those forming NOM composition (humic acids, fulvic acids) and the column had minimum silanol groups. For hydrophobic interactions the stationary phase strength was different to that of the commercial columns and it could selectively elute molecules based on their different masses. The steric selectivity test showed that the stationary phase could separate and distinguish between molecules with similar hydrophobicity and structure but different shapes (o-terphenyl and triphenylene). The Hydrogen bonding capacity (HBC) test showed that the column had minimum silanol groups and the end-capping was successful on the E-PSQ. After fractionation of all the water samples, the MT raw showed NOM peaks around 1.8 mins, 3.4 mins and 5.3, and the final showed NOM peaks around 1.8 mins and 5.5 mins. The Mid-Vaal (MV) raw and final samples shows NOM peaks at around 1.8 mins and 6 mins. The Preekstoel (P) final water had one NOM peak at around 1.8 mins and raw samples had two NOM peaks around 1.8 mins and 6 mins. / Chemistry / M. Sc. (Chemistry)