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A number of industrially relevant separation processes involve carboxylic acids. Carboxylic acids are also amongst the various oxygenated products found in aqueous waste streams or as by-products of industrial operations in Sasol’s Fischer Tropsch processes. Other by-products include alcohols and ketones. Accurate vapour-liquid-equilibrium (VLE) data are required for the efficient and optimal modeling and simulation of these processes. In addition, removing and separating these components will help to prevent their pollution and the associated impact on the environment. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

The regioselectivity of the reaction of hydroxyl radical addition to toluene and naphthalene are examined in this study over the temperature range of 25°C-45°C. Also, the relative rates of reactivity as compared to benzene are determined for toluene, naphthalene, mesitylene, and p-xylene over the same temperature range. 2-(t-Butylazo)prop-2-yl hydroperoxide was used as the hydroxyl radical source and 1,1,3,3-tetramethylisoindolin-2-yloxyl was used as radical trap. For toluene the relative rates of addition were found to be 4 times greater for the ortho position versus the meta postion and 2 times greater for the para position versus the meta position, when the number of meta and para sites are taken into account. / Department of Chemistry

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Hydrocarbon contamination of soils has increased worldwide and bioremediation offers an attractive and environmentally friendly solution to this problem. However, the efficiency and completion of remediation must be assessed using environmental risk assessment criteria. As a result, a variety of indicators have become essential for determining and evaluating recovery of contaminated soils. In this study, microbiological and toxicological assays are used to support traditional chemical analyses, to identify a suite of assays suitable for determining a Soil Recovery Index from Pollution (SRIP). Microbiological assays used are microbial biomass carbon (Cmic), plate counts for culturable degraders and general heterotrophs enzyme activities (dehydrogenase and phosphatase), basal respiration, Substrate Induced Respiration (SIR), and bacterial biosensor. Toxicological response assays of higher organisms include two species of earthworms (Eisenia fetida and Lumbricus terrestris), also, plant assays, including seed germination, root elongation, germination index and plant shoot height performed using two species of plant wheat (Triticum aestivum L.) and white mustard (Brassica alba L.). All assays were applied sequentially to kerosene and diesel amended soils for both incubated and non–incubated treatments. The indicators were discriminated in terms of their sensitivity using a ranking system. The data collected were integrated into a single numeric value to reflect a ‘level of concern’ for each soil treatment. Soil characteristics and hydrocarbon types play key roles in the response of these indicators. The soil that had high organic matter and clay content was less affected by hydrocarbons. For the freshly hydrocarbon amended soils, kerosene was more toxic than diesel, however the opposite was found in the incubated hydrocarbon amended treatments. The most sensitive and robust indicators were basal respiration, bacterial heterotrophs and degraders counts, bacterial biosensors (methanol extracted soils), earthworm survival, mustard root elongation and mustard plant shoot height. Sensitive indicators were inserted into the SRIP. The SRIP indicates the “level of concern” for each soil treatment in a single value.