WS2@FeBC assisted Fe(III)-activated percarbonate for roxarsone and tetracycline simultaneous removal: Interfacial fenton-like process enhanced by oxygen vacancies and tungsten redox

Sodium percarbonate (SPC) has garnered significant interest for its application in water decontamination via advanced oxidation processes (AOPs), however, SPC Fenton-like processes are always hindered by slow iron cyclic conversion and the production of ferric sludge, which limit their efficiency and practicality. Herein, a novel strategy was proposed to greatly improves the Fe(II)/Fe(III) cycling by utilizing oxygen vacancies (O-V) in conjunction with W(IV)/W(VI) redox couples synergistically. In the optimized WS2@FeBC/Fe3+/SPC system, over 97 % removal efficiencies were achieved for both tetracycline (TC) and roxarsone (ROX) within just 10 min. Furthermore, the WS2@FeBC/Fe3+/SPC system exhibits robust performance across a broad pH range (3 to 11) and maintains high removal efficiencies above 90 % even after seven reuse cycles. Quenching experiments combined with electron paramagnetic resonance (EPR) and open-circuit potential measurements indicate that surface-adsorbed hydroxyl radicals (center dot OHads) and direct electron transfer are crucial for TC/ROX degradation. Density functional theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) analyses reveal that oxygen vacancies enhance H2O2 activation to produce center dot OHads, while sulfur vacancies accelerate the W(IV)/W(VI) redox process by mediating localized electron density around tungsten, thereby promoting the Fe(III)/Fe(II) cycling. This study provides a novel perspective on the surface interfacial reactions between reactive oxygen species (ROS) and organic pollutants, offering significant advancements in understanding and improving AOPs for water treatment.