Abstract
The degradation of 10–30 l of a 1000 ppm aniline solution in 0.050 M Na 2SO 4+H 2SO 4 at pH 3.0 and 40 °C by Electro-Fenton ® and peroxi-coagulation processes at constant current until 20 A has been studied using a pilot flow reactor in recirculation mode with a filter-press cell containing an anode and an oxygen diffusion cathode, both of 100 cm 2 area. H 2O 2 is produced by the two-electron reduction of O 2 at the cathode, being accumulated with a current efficiency between 60% and 80% at the first stages of electrolyses performed with a Ti/Pt anode. In the presence of 1 mM Fe 2+, less H 2O 2 is accumulated, but it is not detected using an Fe anode. The Electro-Fenton ® process with 1 mM Fe 2+ and a Ti/Pt or DSA ® anode yields an insoluble violet polymer, while the soluble total organic carbon (TOC) is gradually removed, reaching 61% degradation after 2 h at 20 A. In this treatment, pollutants are preferentially oxidized by hydroxyl radicals formed in solution from reaction of Fe 2+ with H 2O 2. The peroxi-coagulation process with an Fe anode has higher degradation power, allowing to remove more than 95% of pollutants at 20 A, since some intermediates coagulate with the Fe(OH) 3 precipitate formed. Both advanced electrochemical oxidation processes (AEOPs) show moderate energy costs, which increase with increasing electrolysis time and applied current.
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