Gamma radiation-induced decomposition of pentachlorophenol (PCP) in the presence of hydrogen peroxide (H_2O_2) in aqueous solution

The synergistic decomposition of pentachlorophenol (PCP) was performed by gamma irradiation with hydrogen peroxide (H2O2) in aqueous solution. The PCP solution with initial concentration of 27.7 mg·L-1 was irradiated in the presence of extra H2O2 at initial concentrations of 0,50,and 100 mg·L-1. The experimental results showed that the decomposition of PCP conformed to pseudo first-order reaction kinetics under all applied conditions. When the initial H2O2 concentration was in the range of 0~100 mg·L-1,a higher concentration of H2O2 was more effective for the decomposition,mineralization and chlorine release of PCP. The removal of PCP and chlorine release were almost complete at an adsorbed dose of 12 kGy. However,the removal of total organic carbon (TOC) was not as effective as that of PCP. At an adsorbed dose of 12 kGy with initial H2O2 concentrations of 0,50,and 100 mg·L-1,the removal efficiencies of TOC were only approximately 25%,40%,and 54%,respectively. Major intermediates,including carboxylic acids were identified by LC/MS and IC. Possible reactions in radiolytic decomposition of PCP in aqueous solution are proposed.