75 / 2023-06-27 11:58:01

Radical quantification and toxicity assessment of ATZ degradation by S(IV)/ClO2 system

S(IV)/ClO2 system,radical quantification,disinfection byproducts,toxicity assessment

A novel advanced oxidation process S(IV)/ClO₂ has recently been proposed to eliminate refractory organic matters in micro-polluted water. It is urgent to study the characteristics of S(IV)/ClO₂ system from multiple perspectives since there are few research at present. In this study, atrazine (ATZ) was chosen as target pollutants to quantitatively analyze the radicals in S(IV)/ClO₂ system, in which ClO·, SO₄^·-, ·OH were identified as the main active species that play the role of ATZ degradation. The steady state concentration of ClO·, SO₄^·-, ·OH were 5.8×10^-13 mol/L, 9.6×10^-12 mol/L and 3.1×10^-11 mol/L when the dosage of S(IV) and ClO₂ were 200 μM and 100 μM. And the rates at which those radicals contributed to the degradation of ATZ were 53.8%, 43.9% and 2.3%, respectively. In addition, the inorganic disinfection byproducts produced by S(IV)/ClO₂ system were primarily ClO₃^- in acidic conditions, but ClO₂^- in neutral and alkaline conditions. None of the trihalomethanes and haloacetic acids were observed in S(IV)/ClO₂ system. Meanwhile, the toxicity during ATZ degradation by S(IV)/ClO₂ system was investigated by using chlorella pyrenoidosa as subject organism, which was found to be toxicity reduced after treatment. According to the calculated toxicity value, most of the intermediate products of ATZ degradation by S(IV)/ClO₂ system have lower biological toxicity than ATZ, with the exception of ATRA-imine. The results of this study provide muti-angle information about the S(IV)/ClO₂ system that may be useful for its application in water treatment.