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.