Geochemical Aspects of Waste Disposal

Abstract

The work began with an investigation of methods of determination of phenol in solution and was extended to investigate ways of rendering phenol harmless using chemical means applicable to conditions encountered at a waste disposal site. In addition the possibility of finding a catalyst which may promote chemical reactions of phenol to afford less environmentally problematic compounds was investigated. Attention was devoted to catalysts which may be supported on clays, such as montmorillonite and decompose phenol. Hence certain copper(II) complexes which could catalyse ring opening reactions of phenols under homogenous conditions were considered. The preparation of these copper(II) complexes and their characterisation are reported in this work. Phase-transfer catalysis is used to convert phenols to ethers in the presence of montmorillonite. Extension of this method to other systems of chemical interest are described. The interaction of different copper(II) compounds with montmorillonite was studied by means of electron spin resonance spectroscopy and X-ray powder diffraction. A significant effect was observed on the exchange-absorption of the copper(II) ions by clay with different anions. The results indicate that some of the metal taken up by the clay is very labile and could well be remobilised by aqueous media. Also the influence of a high concentration of anion showed that the complex formation between the anion and metal, can result in a lower absorption of the metal from solution. Electron spin resonance and Mossbauer spectroscopies were used to investigate the nature of kaolinite. The results indicate some iron surface contamination and ferric ion substitution for aluminium in the octahedral layer. An investigation of cation exchange on kaolinite surface was carried out using electron spin resonance spectroscopy as the major analytical tool. Two distinct exchange sites were identified.