DESTRUCTION OF ORGANOHALIDES IN WATER USING METAL PARTICLES - CARBON TETRACHLORIDE/WATER REACTIONS WITH MAGNESIUM, TIN, AND ZINC

As a possible method for degrading chlorocarbons in contaminated water supplies, the reactions of metallic magnesium, tin, and zinc with CCl4/H2O mixtures have been studied, in the case of Mg, oxidation by water overwhelmed the Mg-CCl4 reaction. However, Sn and Zn were successfully used to degrade CCl4. Major products in the Sn/CCl4/dH(2)O system were CO2, CHCl3, SnO2, and HCl with smaller amounts of CHCl3 and CH2Cl2. In the case of Zn/CCl4/H2O, the major products were ZnCl2, Zn(OH)(2), and CH4 with CHCl3, CH2Cl2 and CH3Cl as intermediate products. Thus, Sn and Zn behave quite differently with the final carbon-containing product, with Zn being CH4 but with Sn being CO2. This is rationalized by the competing reactions of a possible intermediate Cl(3)CMCl, which can be protonated by H2O to give CHCl3 or eliminate CCl2 (which subsequently reacts with water to form CO2 and HCl). Metal surface areas are also important, and the most active metal samples were prepared by a metal vapor-solvent codeposition method (SMAD cryoparticles). However, conventional Zn dust and Sn granules were also effective, only with lower reaction rates.