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Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references. / Electronic reproduction. / Also available by subscription via World Wide Web / xxvi, 257 leaves, bound ill. 29 cm

The main object of the present investigation has been to establish a titration curve for mohair keratin and to compare it with similar data for wool, to determine whether the differences in physical and chemical properties could be attributed in any way to the acidic and basic character of these fibres. As shown in subsequent discussion such measurements provide extremely useful information regarding the chemical structure of proteins in general, and in the technical fields involving processes such as wool scouring, carbonizing and dyeing. The study has been extended to include certain modified wools, i.e. photochemically damaged, and oxidized keratin. The most successful contribution to the titration data of wool keratin is the work of Steinhardt and Harris and subsequent authors have tended to adopt their procedures without modification. In the present study attempts have been made to obtain a clearer understanding of the fundamental processes. New techniques and analytical methods have been introduced to improve the accuracy of the measurements.

M.Sc. / Inorganic pollutants like heavy metals are some of the major water pollutants worldwide. They are toxic and in some cases carcinogenic even at low concentrations. Their removal from industrial aqueous solutions, wastewater and hydrometallurgical process solutions prior to their release to the environment is necessary for a healthy biosphere which includes human beings, aquatic life and plants. There are several technologies used to remove metals such as Cu, Co, Zn, Hg from water. These include among others, ion exchange, membrane filtration, activated carbon, electrochemical treatment, chemical precipitation, reverse osmosis, coagulation and flocculation. Although they have been used in the removal of metal pollutants from water, these technologies produce high quantities of sludge. They are also expensive to operate and need well trained personnel to operate large chemical plants. Since current metal removal techniques have limitations, a need exists for the development of environmentally friendly and cost effective techniques for the removal of metal ions from aqueous media. The focus of this research project is on the use of micro-organisms as biosorbents for copper and cobalt pollutants in aqueous solutions. The experimental work was carried out on a laboratory scale and a summary of our findings is presented as follows: Synthetic sulphate solutions of copper and cobalt were prepared using CuSO4. 7H2O and CoSO4. 5H2O powders. Concentrations of 0.002 M, 0.07 M and 0.2 M copper and cobalt ions in solution were used as test synthetic solutions for our experiments. Mixed strains of bioleaching bacteria were sourced from Mintek (Randburg, South Africa) to test the viability of this research project. This consortium contained Acidithiobacillus caldus, Leptospirillum spp, Ferroplasma spp and Sulphobacillus spp. These bacteria were able to remove up to 55% copper and 25% cobalt from low concentrated copper and cobalt sulphate solutions with 69% and 58% removal demonstrated in the case of mine effluents emanating from metallurgical operations. Different strains of micro-organisms (bacteria) were isolated from mine dumps and mine operation effluents and soil from the Palabora Mining Company in Limpopo, a northern province in South Africa and Nigel Town in the Gauteng Province. The isolated bacterial strains were then identified using PCR analysis and strains from the Bacillus genre were found to be predominant. Shewanella spp was also present. Pseudomonas spp was isolated using Pseudomonas agar base. These bacteria were then cultured at different species-specific culture conditions and their capabilities to remove copper and cobalt ions first from synthetic solutions and subsequently from mine effluents emanating from metallurgical operations were tested. In the first stage of biosorption experiments, factors that affect biosorption mechanisms which include, solution concentration, biomass concentration, pH, contact time and the presence of other metal co-ions were investigated. A decrease in the amount of metal sorbed as solution concentrations increased was observed with all the bacterial strains. An increase in metal sorption was also observed when biomass concentration was increased. The pH was found to be a species dependant parameter.

LD2668 .T4 1940 A9 / Master of Science

LD2668 .T4 1954 H9 / Master of Science

No description available.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in, Microbiology and Biotechnology 2016. / Heavy metal contamination, of natural water resources, resulting from the large amounts of toxic waste generated by industrial practices is of great environmental concern. Lead (Pb) in particular is one of the most toxic heavy metals that leads to several health deficiencies upon human exposure. The reduction of heavy metals like Pb to acceptable levels in the water therefore becomes critical for potable and agricultural use. Removal of heavy metals by conventional methods is expensive and results in secondary pollution. Bioremediation, a process that passively removes heavy metals from solution through microbial biosorption, is a much sought after alternative because it is more eco-friendly and cost-effective. Micrococcus luteus and Paenibacillus castaneae are two bacterial species reported to be highly resistant to Pb making them favourable as metal biosorbents. The present study aimed to further characterise these species as biosorbents by evaluating the influence of environmental conditions on their rate of biosorption of Pb. Each bacterial isolate was heat-killed and exposed to 0.5 mM (150 mg/L) Pb and the maximal rate of metal uptake calculated when the pH, temperature and biomass concentration were varied. Additionally, the initial metal concentration was increased from 0.005 to 1.25 mM to determine its effect on Pb uptake by each species. The influence of competing cations (Ni2+, Co2+, Mn2+ and Zn2+) on the rate of Pb uptake by each isolate was also established. Both bacterial isolates resulted in the biosorption of at least 50% of 0.5 mM Pb ions when used at a pH of 7, temperature of 25 oC, and a biomass concentration of 2 g/L. The rate of metal uptake for M. luteus at the above mentioned parameters was found to be 24.51 mg/g biomass, while the rate of metal uptake for P. castaneae was 15.63 mg/g biomass. These findings indicated that M. luteus took up more Pb at a faster rate in comparison to P. castaneae. The present study furthermore elucidated that as the metal concentration of Pb was increased, the amount of Pb biosorbed by M. luteus decreased from 84.76% to 46.10%. Similarly, P. castaneae yielded 81.39% biosorption from 0.005 mM Pb but only 34.29% of Pb was taken up when the concentration was increased to 1.25 mM. When the bacteria were exposed to various competing cations an increase in the rate of Pb biosorption was observed for P. castaneae while the opposite effect was noted for M. luteus. Findings from this study show that under high metal concentrations, both M. luteus and P. castaneae are capable of significantly reducing the level of Pb from pure solution. The results warrant further treatment of several industrial effluents using these biosorbents for subsequent application in wastewater treatment. / MT2017

Thesis (M.Sc.(Chemical Engineering))--University of the Witwatersrand, Faculty of Engineering, 1987. / Experimental work showed that the adsorption of the aurocyanide ion by activated carbon is under film diffusion control until the carbon reaches 70 per cent of its equilibrium loading capacity. A rate expression based on the classical film diffusion rate expression is suggested and the model for the batch test developed. The proposed model is shown to simulate batch adsorption tests at different ratios of carbon mass to solution volume. The mass transfer coefficient was linked to the carbon particle size and agitation rato by the use of dimensionless numbers. Correlations are suggested for fixed beds, fluidized beds and rolling bottles. It was determined experimentally that, at equivalent Reynolds numbers, the fixed bed provides the optimum system for mass transfer.