Use of quasi-3-dimensional porous electrodes for adsorption and electrocatalytic removal of impurities from waste-waters

The use of high-area C-felt electrodes as interfaces for in situ adsorptive or electrocatalytic removal, or modification of noxious pollutants in waste-waters is described. Such materials enable diffusion-limited rates of adsorption and electro-oxidative or reductive processes to be effectively enhanced in a major way. Applications are made to removal of pollutants such as salts of S-containing anions, K-ethylxanthate, phenol, aniline and its sulphate, and choline hydroxide from aqueous solutions at low concentrations. It is shown how the courses of the adsorptive and electrosorptive processes can be sensitively followed by means of in situ UV-visible spectrophotometry and, in the case of traces of S-containing anions, using in situ conductimetry. The spectrophotometry technique also provides accurate information on kinetics of the adsorption processes that are usually pseudo-first-order. Complementary studies of electrooxidation of ethylxanthate, choline hydroxide and phenol at Pt gauze electrodes by means of cyclic voltammetry and chronoamperometry are reported. (C) 2001 Elsevier Science Ltd. All rights reserved.