Decomposition of atrazine by ionizing radiation: Kinetics, degradation pathways and influence of radical scavengers

This study reports the radiation-induced degradation of an extensively used carcinogenic, endocrine disrupting and persistent herbicide, atrazine, in aqueous solution. The atrazine degradation rate was directly proportional whereas the dose constant was inversely proportional to the irradiation dose rate and initial atrazine concentration. The second-order rate constant of atrazine with e(aq)(-) and H center dot were found to be 3.70 x 10(9) and 4.84 x 10(8) M-1 s(-1), respectively. Humic acid has synergistic whereas hydrogen peroxide and chloroform have an inhibitory impact on atrazine degradation. Atrazine degradation was reduced in the presence of 1 mM of each of NO3-, NO2-, Br-, SO42-, HCO3- and CO32- due to their competition for reactive radicals with atrazine. The attack of e(aq)(-) and (OH)-O-center dot on atrazine successfully mineralized the organic chlorine and nitrogen to chloride, nitrate and ammonium ions, in addition to the formation of acetate ions from carbon atoms of side chains. Potential detoxification of atrazine solution could be revealed from 83% loss of chloride ion at an absorbed dose of 4000 Gy. The findings of this study suggested that atrazine can efficiently be removed from water by gamma-ray irradiation even in the presence of organic and inorganic radical scavengers commonly found in natural water. (C) 2015 Elsevier B.V. All rights reserved.