Degradation of acetochlor via the UV/persulfate process: Mechanisms, kinetics, and pathways

The environmental health risks of acetochlor (ACE) have received widespread attention. The removal of ACE via the ultraviolet/persulfate (UV/PS) process was investigated in this study. The degradation of ACE in the UV/PS process fitted pseudo-first-order kinetics. ACE can be effectively removed in the pH range of 5.0-9.0. In addition, the removal efficiency of ACE increases with the increase in PS concentration. The experimental and calculation results prove that the contributions of UV irradiation, sulfate radicals (SO4 center dot-) and hydroxyl radicals (HO<middle dot>) were 40, 52.1, and 6.43%, respectively. And the second-order rate constants between SO4 center dot- and HO<middle dot> with ACE are 3.5 x 10(9) and 5.6 x 10(9)M(-1)s(-1), respectively. The influences of different water matrices were explored. Both chloride ions and bicarbonate can inhibit the degradation of ACE, while the effects of sulfate ions and nitrate can be negligible. Humic acid (HA) has an inhibitory effect of ACE degradation. The intermediates were detected and the possible degradation pathway of ACE was proposed. The results of this study can provide technical support for the control of ACE in the environment.