The degradation of Fenuron in water by activated persulfate oxidation: An analysis of efficiency, influential parameters and potential applicability

Abstract

Fenuron (FEN), a member of phenylurea herbicides can be regarded as water contaminant due to its persistence in environment. Persulfate (PS) oxidation as a highly effective degradation technique was applied to degrade FEN using ferrous sulfate (FeSO4), pyrite (PyR; FeS2) and zero-valent iron (ZVI) to activate PS. The systems’ efficiency followed the order as: ZVI-PS system > PyR-PS system > FeSO4-PS system; where, respective degradation of 0.12 mmol/L FEN was 97.5%, 63.6% and 57.8% after 60 min. Therefore, ZVI-PS system was chosen for subsequent detailed analysis and the effects of several influential parameters including ZVI dosage, PS concentration, initial pH, FEN concentration and initial temperature were examined via kinetic studies. ZVI-PS system induced more than 85.0% degradation of 0.06–0.24 mmol/L FEN at initial pH 2.52 to 9.0. Further, difference in initial temperature had an insignificant effect on degradation. ZVI-PS system induced FEN mineralization of about 86.0% after 360 min. Electron paramagnetic resonance (EPR) analysis and free radical quenching (FRQ) analysis were used to demonstrate degradation mechanism by ZVI-PS system. EPR analysis supported that sulfate (SO4−) as well as hydroxyl (OH) radicals were generated in ZVI-PS system; however, FRQ analysis showed that SO4− was dominant reactive radical to carry out FEN degradation. The degradation efficiency of ZVI-PS system was found higher in real waters, which shows its potent applicability to degrade FEN in field. The study concludes that ZVI-PS system can efficiently degrade FEN and may contribute as basic information for future research for the removal of phenylurea herbicides.