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

Activation of S 2 O 8 2− by Fe 2+ 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 S 2 O 8 2− by Fe 3+ -tartaric acid complex at circumneutral pH. The results showed that UVA irradiation induced a rapid photogeneration of Fe 2+ from Fe 3+ -tartaric acid complex at circumneutral pH, by which efficient photo-Fenton activation of S 2 O 8 2− was obtained to generate sulfate radical (SO 4 •- ), as evidenced by radical quenching study in combination with electron spin resonance measurement. The process efficiency was optimized in terms of the tartaric acid:Fe 3+ ratio, Fe 3+ -tartaric acid complex dosage, S 2 O 8 2− dosage and UV fluence. Notably, the photo-Fenton catalytic efficiency of Fe 3+ -tartaric acid (1:1) complex for S 2 O 8 2− was comparable to the Fe 3+ -EDDS (1:1) and Fe 3+ -citric acid (1:1) complexes, and more efficient than the Fe 3+ -NTA (1:1), Fe 3+ -EDTA (1:1), Fe 3+ -oxalic acid (1:1) and Fe 3+ -malonic acid (1:1) complexes. It is noticed that the process efficiency can be hindered by the presence of humic acid, phytic acid and HCO 3 − . Nevertheless, almost complete degradation of carbamazepine in actual secondary effluents at environmental relevant concentration was obtained under the optimal conditions of 100 μM Fe 3+ -tartaric acid (1:1) complex, 2 mM S 2 O 8 2− , pH 5.0–6.0, 25 °C and UV fluence of 5.0 J cm −2 . By considering the promising photo-Fenton catalytic efficiency and environmentally benign manner of Fe 3+ -tartaric acid complex, it has large potential application for the treatment of emerging micropollutant in water.