γ辐照和H_2O_2联合作用下五氯酚(PCP)的降解

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

研究了水溶液中的五氯酚(PCP)在γ辐照和过氧化氢(H2O2)联合作用下的降解.PCP的初始浓度为27.7mg·L-1,外加H2O2的初始浓度为0、50和100mg·L-1.结果表明,PCP在不同条件下的辐照降解符合准一级动力学方程.当外加H2O2的初始浓度在0～100mg·L-1时,PCP的去除率、矿化率和脱氯率随H2O2添加量的增加而增大.当吸收剂量为12kGy时,PCP几乎完全去除,氯几乎完全释放.然而,总有机碳(TOC)的去除率远低于PCP的去除率.当吸收剂量为12kGy,外加H2O2的初始浓度分别为0、50和100mg·L-1时,TOC的去除率仅分别为25%、40%和54%.用LC/MS和IC检测了包括羧酸在内的主要中间产物,探讨了水溶液中PCP可能的辐照降解机理.

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.