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

Abstract

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 (OV) 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 (•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 •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.