DEGRADATION OF ATRAZINE IN WATER BY GAMMA-RAY IRRADIATION

摘要

Atrazine degradation values and the degradation process by gamma-ray irradiation were investigated. The proposed degradation mechanism and change of acute toxic-ity were further examined. Atrazine concentration decreased with increase of irradiation dose, and 99% removal of atrazine at the initial concentration of 0.04 mmol L~(-1) was achieved when 0.8 kGy was selected as the irradiation dose. The process could be depicted by first order reaction kinetics. The contribution to atrazine degradation by the radicals was in the order of·OH > e_(aq) > ·H, and the degradation process was mainly caused by the reaction of atrazine with·OH. The quantum efficiency ratio of ·OH, e_(aq)~-and ·H was calculated to be 5:1:1. The removal efficiency decreased with increase of atrazine initial concentration at the same irradiation dose. H_2O_2, HCO_3~-, NO_3~-, NO_2~- and humic acid as additives reduced the degradation value. Furthermore, the increase of H_2O_2, NO_3~- and NO_2~- would result in the decrease of removal efficiencies. The concentration of Cl~- increased with increase of irradiation dose, and loss of chlorine atoms was realized on atrazine. A remarkable reduction of atrazine was observed by gamma-ray irradiation, but brought to a toxicity increase, and more toxic substances were produced.