Enhancing ferric ion/sodium percarbonate Fenton-like reaction with tungsten disulfide cocatalyst for metronidazole decomposition over wide pH range

To overcome the drawbacks of traditional Fenton method, this work proposed the application of tungsten disulfide (WS2) as the cocatalyst to enhance Fe3+ and sodium percarbonate (SPC) Fenton-like system for metronidazole (MTZ) degradation. MTZ was completely removed after 10 min under the optimum conditions with 1.5 g/L WS2, 2 mmol/L SPC, 1.5 mmol/L Fe3+, and pH 7. And the Fe3+/SPC/WS2 could achieve well performance over a wide pH range of 3–11. WS2 could significantly accelerate the Fe3+/Fe2+ circulation and H2O2 disintegration. The electron paramagnetic resonance and quenching tests discovered that the hydroxyl radicals (HO·) and carbonate radicals (CO3·−) were the crucial active species for MTZ decomposition. The surface valence state of WS2 before and after the reaction was analyzed by X-ray photoelectron spectroscopy, and the Fe3+/Fe2+ cycle was proved to be triggered by the conversion of W4+ to W6+. After fifth cycle, the Fe3+/SPC/WS2 still achieved the MTZ degradation efficiency of 75 %. The decomposition byproducts of MTZ and their biotoxicities were determined by mass spectrometry and toxicity estimation software tool, respectively. This investigation provided an effectively idea for antibiotic removal with the WS2 co-catalytic system.