Biomass-derived in-situ carbonized ferrous sulfide for Fenton oxidation of phenol in wastewater: mechanisms, pathways, and applications

Innovative iron-based nanoparticles (NPs) made from biomass provide sustainable solutions for environmental cleanup, integrating better environmental management with resource recycling. This study introduces biomass-derived carbon-coated iron sulfide (FeS@CMP) as an efficient Fenton catalyst for phenol oxidation, addressing challenges associated with FeS NPs in advanced oxidation processes (AOPs), for example deactivation and aggregation. Firstly, advanced characterization reveals its porous structure, high surface area, and abundant active sites, compared to carbonized biomass precursor (CMP), while FeS@CMP demonstrates superior physical and chemical stability. Secondly, FeS@CMP achieves remarkable efficiency in activating hydrogen peroxide (H 2 O 2 ) for phenol removal (94.08%), which is much greater than that of CMP (40.70%). Further, mechanistic analysis identifies a synergistic electron transfer process involving multiple ROS, including •OH, SO 4 -•, and 1 O 2 , driving effective phenol degradation. Thirdly, using Density Functional Theory (DFT) calculations and Liquid Chromatography-Mass Spectrometry (LC-MS), a specific degradation pathway for phenol is proposed. Finally, toxicity assessments reveal a marked decline in toxicity of degradation products and excellent reusability over multiple cycles. FeS@CMP also effectively degrades contaminants in real wastewater. This study converts waste into high-performance biomass-based catalysts, advancing sustainable development and offering an eco-friendly method for phenol removal, enhancing low-impact AOP technologies.