Pilot scale mineralization of organic acids by electro-Fenton® process plus sunlight exposure

The viability of the electro-Fenton® degradation of aqueous solutions of benzoic acid, 2,4-dichlorophenoxyacetic acid and oxalic acid has been studied at 20 A using a pilot flow reactor containing an anode and an oxygen diffusion cathode, both of 100 cm2 section. Pollutants were preferentially oxidized by hydroxyl radicals formed in solution from reaction of Fe2+ with electrogenerated H2O2, allowing mineralization of benzoic acid and 2,4-D. For oxalic acid no electrochemical mineralization was observed. After electrolysis, samples of the different effluents were exposed to sunlight (Helielectro-Fenton process) and almost complete mineralization was reached after ca. 30-50 min without additional cost. Effects of parameters such as electrolysis time, pH and solar irradiation time on the process efficiencies were studied.