Photocatalytic degradation of phenol by the heterogeneous Fe3O4 nanoparticles and oxalate complex system

A novel approach for the removal of phenol by an advanced oxidation process using Fe3O4 nanoparticles (NPs) and oxalate was proposed and investigated, and the influences of oxalate, Fe3O4 NPs and H2O2 dosage on the photodegradation of phenol were reported. No obvious difference is found between ultraviolet light and visible light exposure, confirmed potential photoactinic roles of Fe3O4 NPs in the presence of oxalate under visible light. Furthermore, relatively high dependence of oxalate depletion was observed due to the initiation of the formation of the Fe(III)-carboxylate complexes for photodegradation via a photo-Fenton-like system. Our results also demonstrated that the photodegradation of phenol occurred by a radical mechanism accompanied with the formation of O-2(center dot) and (OH)-O-center dot radicals, which was further accelerated by the exogenous addition of H2O2. All reactions followed the pseudo-first-order reaction kinetics. The half-life (t(1/2)) of Fe3O4 -oxalate and Fe3O4 -oxalate-H2O2 in the system showed higher efficiencies of photo-Fenton-like degradation routes for phenol. The photo-Fenton-like systems showed a relatively high catalytic ability (> 99.9%) in the removal of phenol at low phenol concentrations below 50 mg L-1, indicating its potential application in the treatment of low concentration wastewater. The results have demonstrated the feasibility of Fe3O4 NPs as potential heterogeneous photo-Fenton photocatalysts for organic contaminants decontamination in industrial wastewater.