The kinetics and mechanism of ozonation degradation of chloronitrobenzenes (ClNBs) in aqueous solution were investigated in a semi-continuous reactor

and the molecular and free radical contribution of ozone to the degradation of ClNBs was also evaluated.The results of kinetic studies showed that the decomposition of ClNBs was a pseudo-first-order reaction with respect to pollutant concentration and the degradation rate was in the order o-CNB<m-CNB<p-CNB.The overall rate constant increased with increasing pH

however decreased with increasing pollutant and free radical scavenger concentration.Furthermore

the TOC removal rate was significantly lower than the degradation rate.Ozonation could not reduce TOC completely

the results of HPLC and GC-MS showed that p-CNB was mainly transformed into p-chlorophenol

p-nitrophenol

2-chloro-5-nitrophenol

etc.

and carboxylic acids with low molecular weight.Finally

it was found through evaluating the contribution of ozone molecule and hydroxyl radical that hydroxyl radical played a decisive role in the removal of ClNBs.Therefore

advanced oxidation processes(AOPs) which enhance the generation of free radicals in eliminating this kind of pollutants from environment may be a preferred choice.