Boosting activation of S2O82- by Fe3+-tartaric acid complex for rapid carbamazepine degradation via photo-Fenton mechanism

Activation of S2O82- by Fe2+ is suppressed under non-acidic pH conditions, strongly hindering its application for water purification. To this end, this study reported an efficient photo-Fenton activation of S2O82- by Fe3+-tartaric acid complex at circumneutral pH. The results showed that UVA irradiation induced a rapid photogeneration of Fe2+ from Fe3+-tartaric acid complex at circumneutral pH, by which efficient photo-Fenton activation of S2O82- was obtained to generate sulfate radical (SO4 center dot-), as evidenced by radical quenching study in combination with electron spin resonance measurement. The process efficiency was optimized in terms of the tartaric acid:Fe3+ ratio, Fe3+-tartaric acid complex dosage, S2O82- dosage and UV fluence. Notably, the photo-Fenton catalytic efficiency of Fe3+-tartaric acid (1:1) complex for S2O82- was comparable to the Fe3+-EDDS (1:1) and Fe3+-citric acid (1:1) complexes, and more efficient than the Fe3+-NTA (1:1), Fe3+-EDTA (1:1), Fe3+-oxalic acid (1:1) and Fe3+-malonic acid (1:1) complexes. It is noticed that the process efficiency can be hindered by the presence of humic acid, phytic acid and HCO3-. Nevertheless, almost complete degradation of carbamazepine in actual secondary effluents at environmental relevant concentration was obtained under the optimal conditions of 100 mu M Fe3+-tartaric acid (1:1) complex, 2 mM S2O82, pH 5.0-6.0, 25 degrees C and UV fluence of 5.0 J cm (2). By considering the promising photo-Fenton catalytic efficiency and environmentally benign manner of Fe3+-tartaric acid complex, it has large potential application for the treatment of emerging micropollutant in water.