Detoxification of aqueous chlorophenol solutions by ionizing radiation

The radiolytic degradation of aerated aqueous 5 x 10(-5) M (6-10 ppm) 2-, 3 - and 4-chlorophenol, 2,4-di- and 2,4,6-trichlorophenol has been investigat ed by determination of the dose needed for complete substrate degradation a s well as by analysing the dehalogenation process, the toxicity and the dis served organic carbon (DOC) in dependence of dose. A radiation dose of 500 Gy leads to a 100% decomposition (corresponding to substrate concentrations less than or equal to 1 x 10(-6) M) for all compounds except 2-chloropheno l, for which 600 Gy are required. No influence of dose rate on the degradat ion rate could be observed in the range from 21 to 183 Gy min(-1). Dechlori nation is completed at 1 kGy, its rate increases markedly with increasing n umber of chlorine atoms. At a dose of 1 kGy the decrease of DOC is approxim ately 20%. A bacterial bioluminescence test was used for evaluating the tox icity of the final radiolytic products. Total detoxification Could be achie ved by carrying out the irradiation procedure under air saturation and by d oses of 500 Gy, which equals that for complete degradation. (C) 1999 Elsevi er Science Ltd. All rights reserved.