Simultaneous electro-oxidation and in situ electro-peroxone process for the degradation of refractory organics in wastewater.

Abstract

During electro-oxidation (EO) wastewater treatment, the applied voltage must polarize both a dimensionally stable anode with a sufficiently high potential to effectively produce hydroxyl radicals (OH), as well as a cathode with a sufficiently low potential to catalyze the H2 evolution reaction (HER). Nevertheless, H2 does not contribute to pollutant degradation and yet increases energy consumption. Inspired by fuel cell technology, in which the O2 reduction reaction (ORR) is catalyzed on the cathode, herein, a carbon nanotube-coated carbon-PTFE gas diffusion electrode was fabricated to catalyze ORR during EO for the treatment of leachate concentrates. In comparison to conventional HER-EO, ORR-EO was shown to save 17.7-23.2% energy consumption. Further, as the cathodic ORR byproduct, H2O2 can react with the ozone generated from the Ti/SnO2-Sb2O5 anode to catalyze the peroxone process, which enhances OH generation for the degradation of organic products. This in situ electro-peroxone process was determined by salicylic acid OH trapping and liquid chromatography. The novel simultaneous EO and in situ electro-peroxone process described herein has great application potential and economic merit in the degradation of refractory organics in wastewater.