Abstract
Reactivity or degradation of 135 pesticides was investigated in waters containing residual chlorine and ozone to clarify their behaviors in water purification processes, and discussed with respect to their molecular structures (or functional groups).
The pesticides were divided into two groups according to their reaction behaviors to chlorine and ozone. One group was for pesticides reactive with chlorine and more reactive with ozone, and another included pesticides undegradable by chlorine but easily degradable by ozone. Function groups or chemical structures reactive with both chlorine and ozone were thiophosphoryl, sulfide, dithiocarbamate, thiocarbamate, uracil and phenol. Ether bond such as aliphatic hydrocarbon (Al)-O-Al and aromatic hydrocarbon (Ar)-O-Al and Cl-unsubstituted C=C (double) bond were degraded not by chlorine but by ozone. Ar-O-Ar ether, ClC=C (double) bond, phosphoryl groups, dinitroaniline and dinitrophenol were undegradable by both chlorine and ozone.
With respect to molecular structure, triazine, acid-amide, carbamate and diphenylether were basically stable against both chlorine and ozone. Reactivity of pesticides including any these structure seemed to be derived from inner side-chain(s) with reactive site(s) for chlorine or ozone.
The results showed that there were much more pesticides reactive with ozone than those with chlorine.
