Synergistic effects of HSO5− in the gamma radiation driven process for the removal of chlorendic acid: A new alternative for water treatment

Abstract

Removal of chlorendic acid, an emerging water pollutant and potential carcinogenic, was investigated by gamma radiation in the absence and presence of peroxymonosulfate (PMS, HSO5−). The removal of chlorendic acid (1.40μM initial concentration) by gamma radiation was promoted with PMS, i.e., 95% compared to 82% in the absence of PMS, at an absorbed dose of 1000Gy. The removal of chlorendic acid by gamma-ray/PMS process was due to OH and SO4−. Second-order rate constants of 5.90×109, 1.75×109, and 2.05×109M−1s−1 for chlorendic acid with eaq−, OH, and SO4−, respectively, were determined. The removal efficiency of chlorendic acid was promoted with increasing initial PMS concentration and decreasing initial target contaminant concentration. The removal of chlorendic acid by gamma-ray/PMS was inhibited in the presence of CO32−, NO2−, p-CBA, m-TA, and alcohols. The presence of Fe2+, Cu+, and Fe3+ with gamma-ray/PMS promoted removal efficiency of chlorendic acid from 78% to 99, 94, and 89%, respectively, at 592Gy. The degradation of chlorendic acid by OH and SO4− was found to be initiated at the carboxylate group as could be revealed from nature of the transformation by-products. Nevertheless, this study concluded that gamma-ray/PMS is of practical importance in treatment of natural water containing chlorendic acid, as potential detoxification of chlorendic acid solution can be revealed from 83% loss of chloride ion at 3000Gy. In addition, gamma-ray/PMS process achieved efficient removal of chlorendic acid even in the presence of commonly found inorganic ions in natural water.