Using Mn/Fe enriched-roots of P. Stratiotes to synthesize multi-metallic catalysts for activating peroxymonosulfate to degrade bisphenol A

Abstract

Aquatic plants used for phyto-extracting toxic metals from water are often enriched in certain metals and recycling these metal-enriched plants will achieve the sustainable application of phytoremediation/phytoextraction technology. The present study systematically explores the potential recycling of Mn-enriched-roots of P. Stratiotes used in the treatment of electrolytic manganese residue leachates as catalysts for activating peroxymonosulfate [1] to degrade organics in water. The effects of heat treatment temperature and atmosphere on the catalyst activity were first investigated and the results indicate that catalyst prepared in air at 400 °C contains active Mn(IV) while Mn(IV) was not detected in the catalyst prepared in N2 at the same temperature, and thereby catalyst obtained in air under 400 °C (MF400) performs better catalytic activity in degrading bisphenol A (BPA). The removal of BPA was found to reach 99.9 % in the MF400/PMS system at 120 min. The BPA degradation pathways were inferred by density flooding calculations (DFT) and then confirmed by liquid chromatography-mass spectrometry coupled detection, indicating that the radical pathway depending on·OH, SO4− and·O2– is the mechanism for BPA degradation in the MF400/PMS system. The ECOSAR assessment reveals that most BPA degradation intermediates are less toxic than their parent molecule. This work provides a simple and effective way for recycling Mn/Fe enriched aquatic plants used in phytoextraction process.