Efficient H2O2 oxidation of organic pollutants catalyzed by supported iron sulfophenylporphyrin under visible light irradiation

An efficient method has been developed to degrade toxic and nonbiodegradable organic pollutants such as Sulforhodamine B (SRB) and 2,4-dichlorophenol (DCP). It is based on the photocatalytic power of iron tetrasulfophenylporphyrin supported on a commercial anionic ion-exchange resin (Amberlite IRA 900) (FePR) to activate an oxidant H2O2 in aqueous media. Visible light irradiation (lambda > 450 nm) significantly accelerates the degradation process. The new catalyst is effective over a wide pH range, and can be easily recycled by filtration. The SRB and DCP were mineralized with yields of 56% and 68% at a catalyst/substrate molar ratio of 1:33 and 1:535, respectively. Moreover, the supported-catalyst would suppress greatly the undesirable side-reaction of H2O2 conversion to O-2. UV-vis spectroscopy, high-performance liquid chromatography, ion chromatography, IR, spin-trapping electron paramagnetic resonance, surface photovoltage spectroscopy, and total organic carbon measurements were used to examine the photoreaction processes. The photocatalytic degradation pathways mainly involve the formation and reaction of (OH)-O-. radicals. On the basis of the experimental results, a possible reaction mechanism is proposed.