Graduation date: 1995

Experiments were undertaken to study in vivo the effect of hexachloronaphthalene in vitamin A metabolism in the rat. The status of vitamin A in the animal was determined by tissue analysis for the vitamin and by visual observation for symptoms of vitamin A deficiency. Four studies were made. The effects of dietary hexachloronaphthalene on preformed residual vitamin A, on assimilation of dietary carotene, on assimilation of a single oral dose of carotene, and on the absorption and storage of a single oral dose of vitamin A palmitate were investigated. In addition, the effect of ingested hexachloronaphthalene on calf plasma protein was studied. The following conclusions were derived from the results of the experiments. 1. The metabolism of dietary hexachloronaphthalene resulted in an increased requirement for vitamin A in peripheral tissue. This effect was apparently separate from the liver hypertrophy and fatty infiltration which are characteristic results of chlorinated naphthalene ingestion in rats. The mechanism of this increased demand for vitamin A was not discerned. Vitamin E supplementation was or no apparent value in preventing this increase in the requirement for vitamin A. 2. The addition of vitamin E to carotene-rich diets normally produces an increased yield of vitamin A. This stimulus of carotene conversion was not apparent when hexachloronaphthalene was included in the ration. 3. The ingestion of dietary hexachloronaphthalene depressed the ability of the rat to convert carotene to vitamin A. This was not true when the total dose of the toxic compound was included in the carotene solution. The addition of a bile salt to the carotene solution was not or value in preventing the depression of carotene conversion. Neither, however, did it stimulate conversion in the normal animals as was expected. 4. The ingestion of dietary hexachloronaphthalene had no apparent effect on the ability of the rat to absorb and store a single oral dose of vitamin A palmitate. 5. Paper electrophoresis studies and analysis of changes in TCA precipitable plasma protein in calves indicated that a depression of the level of the plasma proteins, especially the albumins, was a manifestation of the ingestion of hexachloronaphthalene by these animals. / Master of Science

At present, South Africa has inadequate technology to destroy its hazardous waste, with approximately 18000 litres of chlorinated hazardous waste stored in this country. Approximately 800 tons of banned or obsolete chemicals are to be sent to Pontypool. Wales, for incineration, at a considerable cost. Because of the toxic nature of chlorinated waste and their long-term effects on the environment , a sustainable method of dealing with this type of waste is essential. Gas phase destruction of methylene chloride, trichlorobenzene and lindane by pyrolysis (i.e. heating in the absence of oxygen) was attempted. Destruction was effected by high temperature thermal degradation of molecules into free radicals. These radicals then combine to form hydrogen chloride and carbon as major products. This method was chosen so as to eliminate the possible formation of highly toxic oxygenated derivatives such as polychlorinated dibenzofurans and dibenzodioxins that can be formed during incineration if strict control is not excercised. The reactor assembly was built in the Department of Chemical Engineering at the University of Natal. 11 incorporates aspects of many different previously designed reactors, as discussed in the text. Heat for the reactions was supplied by induction. A high frequency induction unit supplied current to a copper coil. The resulting magnetic field induced current to flow in a susceptor housed within the copper coil. The susceptor in this case was a graphite tube, which served as both the heating element and the thermal radiation source, in addition to forming the walls of the reaction zone. Up and down stream processes were designed and experiments were carried out in which reaction temperatures (348-1400°C) and residence times (1.3-5.6 seconds) were varied. Destruction efficiencies of 100% and 99.99% were obtained for methylene chloride and trichlorobenzene respectively, with inert argon used as the carrier gas. These destruction efficiencies comply with the 99.99% stipulated by the United States Conservation and Recovery Act. A cause for concern was the formation of chlorinated benzenes and naphthalenes. Destruction of lindane proved unsuccessful due to limitations in the vapourisation and feed system and will have to be investigated further. The method of induction heating was evaluated to be 98.9% thermally efficient. Raw material and utility consumption per ton of waste destroyed by the pyrolysis process was compared to values for incineration as well as the plasma arc and catalytic extraction processes. Consumption for pyrolysis compares favourably with all three processes and suggests that the process could be competitive. Claims to the success of the technology on a wide scale are limited by the small number of compounds that were successfully pyrolysed. Results do however indicate much promise for this technology to be used as a fi nal chlorinated waste destruction unit on an existing process. Modifications to the existing reactor to improve product recovery and analys is will allow for temperature and residence time optimisation for a variety of wastes. Additional in strumentation and process control will allow for kinetic studies to be undertaken in future. This project should be considered as the first step in an ongoing series of research and subsequent improvements to the technology presented here. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.

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