Interfacial complexation between Fe3+ and Bi2MoO6 promote efficient persulfate activation via Fe3+/Fe2+ cycle for organic contaminates degradation upon visible light irradiation

To address the observed decrease in efficiency during Fe2+-mediated persulfate (PDS) activation caused by slow electron transfer rates and challenges in cycling between Fe3+/Fe2+ states, we devised a strategy to establish interfacial complexation between Fe3+ and Bi2MoO6 in the presence of PDS. The proposed approach facilitates more efficient capture of photogenerated electrons, thereby accelerating the rate-limiting reduction process of the Fe3+/Fe2+ cycle under visible light irradiation and promoting PDS activation. The Bi2MoO6/Fe3+/PDS/Vis system demonstrates complete degradation of organic pollutants, including Atrazine (ATZ), carbamazepine (CBZ), bisphenol A (BPA), and 2,4-dichlorophenol (DCP) at a concentration of 10 mg/L within a rapid reaction time of 30 min. Radical scavenging experiments and electron paramagnetic resonance spectra (EPR) confirm that the sulfate radical (•SO4−) is the dominant species responsible for organic contaminant degradation. The real-time conversion process between Fe3+ and Fe2+ was monitored by observing changes in iron species forms and concentrations within the reaction system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy verify the formation of a complexation between Fe3+ and Bi2MoO6, facilitating anchoring of Fe3+ onto material surface. Based on these findings, we propose a reliable mechanism for the activation reaction. This work presents a promising heterogeneous PDS activation method based on Fe3+/Fe2+ cycle for water treatment.