Abstract: The electrochemical oxidation degradation process of substituted aniline with electron-donating group(—CH₃) and electron-withdrawing groups(NO₂, Cl^-) was studied on PbO₂/Ti electrode by using sulfate as the support electrolyte. The results show that the oxidation degradation routes of substituted aniline were all started from hydroxyl radical attacking to form anilinophenol compound, then the anilinophenol compound changed into quinone intermediate on the electrode surface by the losing electron. The electrocatalysis degradation rate of substituted aniline with electron-doning groups was higher than the one with electron-withdrawing groups, because of the higher electron cloud density of benzene ring, it is convenient for hydroxyl attacking. On the contrary, it was difficult for hydroxyl attacking because electron-withdrawing groups could make the electron cloud density of benzene ring lower. The chemistry reaction activity is not consistent with electrochemistry reaction activity for the reason of cathode deoxidization reaction. When the hydroxyl radical attacks the chloroaniline, —Cl leaves and Cl^- enters the electrolyte, at the same time, it is oxidized into available chlorine and the degradation rate increased. Although the nitro group is a strong electron-withdrawing group, it can be changed into p-phenylenediamine, then the benzene ring activity was stimulated, finally its degradation rate is much higher.

Key words: Electrochemical oxidation, Substituted aniline, Hydroxy radical