Use of an Acidic Fe /  O 2 Cell for Wastewater Treatment: Degradation of Aniline

Abstract

Solutions containing 0.50 mol dm Ϫ3 Na 2 SO 4 and aniline concentrations between 129 and 1000 ppm have been decontaminated using an acidic Fe/O 2 cell with an Fe anode and a carbon-poly(tetrafluoroethylene) O 2 -fed cathode. This system produces spontaneously strong oxidizing radicals, such as OH • and HO 2• , which react with pollutants. Decontamination is more efficient for solutions with pH > 3 where intermediates coagulate with the Fe(OH) 3 precipitate formed. A 95% degradation is reached after 1 h of treatment of 129 ppm of aniline at initial pH 4 and at 35ЊC. For higher substrate levels, pollutants are quickly destroyed if the pH is regulated between 4 and 5. After 2 h, solutions up to 500 ppm of aniline are almost completely degraded, whereas 81% of the degradation is reached for 1000 ppm of substrate. Benzoquinone and nitrobenzene are detected as intermediates. An insignificant accumulation of these products is found in the treatment of 1000 ppm of substrate, suggesting the formation of polymers that coagulate with the Fe(OH) 3 precipitate. Low concentrations of ammonium and nitrate ions have been determined in treated solutions. The major part of the initial carbon and nitrogen is retained in the precipitate, indicating that coagulation of intermediates predominates over their mineralization. A reaction pathway for the degradation of aniline involving all intermediates detected is proposed.

Electrochemically derived functionalized graphene for bulk production of hydrogen peroxide

“…Alternative routes for peroxide generation include direct preparation of H 2 O 2 from oxygen and hydrogen, oxidation of alcohols [5], photocatalysis [6], and electrochemical processes such as the electro-Fenton process [7], microbial electrosynthesis [8], and proton ex-change membrane (PEM) assisted synthesis [9]. Further, in situ generation of peroxide from dissolved oxygen via electrochemical ORR is identified as an effective route for water treatment technology, where economically viable, biologically friendly, sustainable catalysts are required [10][11][12][13][14].…”

Effect of oxygen pressure on the electrochemical oxidation of Chrome Brown azo dye

“…The review [12] presents data on the existing electrochemical techniques for detoxication of dye-containing wastewater. Advantages of the electrochemical detoxication of dyes on various electrode materials via generation of active chlorine and hydroxy radicals involved in the oxidation process are discussed.…”