Mineralization of aromatics in water by sunlight-assisted electro-fenton technology in a pilot reactor

The viability of the degradation of aqueous solutions of aniline, nitrobenzene, and 4-chlorophenol by the so-called Photoelectro-Fenton process in a pilot reactor is reported. The Electro-Fenton process stage, based on the flow of oxygen through a gas diffusion cathode to produce H2O2, allows mineralization of about a half of the TOC content in ca. 1 h, because anodic oxidation is coupled with Fenton reaction in the presence of Fe2+ catalyst. An intensity of 20 A was applied in a flow cell comprising a Ti/Pt anode and a carbon-PTFE cathode. After electrolysis, samples of the effluent were exposed to sunlight, and almost complete mineralization was reached after ca. 50 min. Effect of parameters such as electrolysis time, pH, initial concentration, and solar or UVA irradiation on the process efficiencies and the running costs are studied. The Photoelectro-Fenton process using sunlight effectively diminishes these costs. The analogous behavior of the three aromatics suggests similar degradation pathways, regardless of the different groups attached to the ring.