DEHALOGENATION OF HALOGENATED ORGANIC-COMPOUNDS IN AQUEOUS-SOLUTION BY DIFFERENT PHOTOCHEMICAL METHODS

Given the toxicity of halogenated organic compounds and their wide use and, hence, presence in the environment, especially in the hydrospher e, continuous monitoring of surface and phreatic waters as well as of the drinking water quality is needed. Aiming at a new analyzing equipm ent for the determination of the total organic halide content (TOX) in the aqueous phase based on a photochemical or photoinduced degradatio n of organic halides, we made comparative studies, which were focused on halide mass balance of dehalogenation implying photolysis, vacuum-u ltraviolet (VUV)-photolysis and (photo)- electrochemical reduction. Wi th the exception of photolysis of halogenated hydrocarbons, an methods meet the requirement of total and exclusively conversion of the organ ically fixed halogen to halide ions, which may then be determined by e lectrochemical methods. At present, only VUV photolysis using miniatur ized Xe-excimer lamps has been used successfully under conditions of c ontinuous on-line analysis. However, the photoelectrochemical process will also meet these requirements after optimizing the cell design and the doping level of p-SiC electrodes.