Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system

Abstract

In this study, batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system (mFe/Cu-air-PS) for p-nitrophenol (PNP) treatment in aqueous solution. First, the optimal operating parameters (i.e., aeration rate of 1.0 L/min, theoretical Cu mass loading (TMLCu) of 0.110 g Cu/g Fe, mFe/Cu dosage of 15 g/L, PS total dosage of 15 mmol/L, feeding times of PS of 5, initial pH 5.4) were obtained successively by single-factor experiments. Under the optimal conditions, high COD and TOC removal efficiencies (71.0%, 65.8%) were obtained after 60 min treatment. Afterword, compared with control experiments (i.e., mFe/Cu, air, PS, mFe/Cu-air, mFe/Cu–PS, air-PS and mFe-air-PS), mFe/Cu-air-PS system exerted superior performance for pollutants removal due to the synergistic effect between mFe/Cu, air and PS. In addition, the results of control experiments and radical quenching experiments indicate this reinforcement by feeding of PS was greater than by aeration in mFe/Cu-air-PS system. Furthermore, the degradation intermediates of PNP in mFe/Cu-air-PS process were identified and measured by HPLC. Based on the detected intermediates, the degradation pathways of PNP were proposed comprehensively, which revealed that toxic and refractory PNP in aqueous solution could be decomposed effectively and transformed into lower toxicity intermediates. As a result, mFe/Cu-air-PS system with the performance of oxidation combined reduction can be also a potential technology for the treatment of toxic and refractory PNP contained wastewater.