PEROXI-COAGULATION OF ANILINE IN ACIDIC MEDIUM USING AN OXYGEN DIFFUSION CATHODE

A novel electrochemical method for wastewater treatment, called peroxi -coagulation, is presented in this paper. Degradation of aniline in ac idic solution of pH similar to 3 has been studied using this method. E lectrolyses were performed in an undivided cell with an Fe anode and a carbon polytetrafluoroethylene O-2-fed cathode which continuously ele ctrogenerates H2O2. The anode dissolves yielding Fe2+ and Fe3+. This l ast ion gives a precipitate of hydrated Fe(III) oxide. Aniline and its intermediates are oxidized mainly by reaction with OH., which is prod uced from Fenton's reaction between electrogenerated H2O2 and Fe2+. Co mpetitive coagulation of oxidation products with the hydrated Fe(III) oxide precipitate also occurs. These processes allow a fast and almost complete total organic carbon removal for aniline solutions in short time electrolyses. The method has higher decontamination power than ot her electrochemical treatments tested, such as electrocoagulation with a graphite cathode, and electro-Fenton and photoelectro-Fenton with a Pt anode. Benzoquinone, nitrobenzene, NH4+, and NO3- were detected in electrolyzed solutions. Precipitates contain coagulated organics with a major proportion of nitrogen-containing compounds. A pathway for an iline peroxi-coagulation involving these species is proposed.