Solar photoassisted advanced oxidation of synthetic phenolic wastewaters using ferrioxalate complexes

In this work, the performance of advanced oxidation solar assisted photochemical treatments of synthetic phenolic type wastewaters was studied at natural pH conditions, and with phenol concentrations in the range of 180–733 mg/L. The photochemical treatment was mediated with ferrioxalate and peroxide in two CPC (compound parabolic collector) photoreactors of different volumes and operation conditions (batch and with closed flow). Phenol transformation efficiencies of 100% and total COD reduction percentages of 85% were reached within the first hour of phototreatment, having as final product an aromatics free effluent, in both types of reactors. The ferrioxalate type complexes using mass ratios of oxalate/phenol = 1.5, oxalate/Fe3+ = 15 and H2O2/phenol > 5.0 showed to be very effective in the treatment of these effluents, even at pH conditions close to neutrality, pH region in which the Fenton type processes begin to lose efficiency due to the precipitation of iron as a hydroxide.