Defect engineering of coal tailings induce peroxymonosulfate activation for phenol wastewater degradation

The valorization of coal tailings presents an essential approach to addressing their significant environmental challenges. This study employs a defect engineering approach by introducing a significant number of sulfur vacancies (SVs) on the surface of coal tailings to activate peroxymonosulfate (PMS) for the efficient degradation of phenol wastewater. In the coal tailings/peroxymonosulfate (ICT/PMS) system, phenol was completely degraded within 30 min at pH= 7 with 0.3 g coal tailings and 4 mM PMS. Additionally, comparative analysis identified SVs as the key factor enhancing phenol degradation via Fe-S synergy. XPS confirmed ball-milling increased S²⁻ content from 27.65 % to 58.04 %, promoting iron redox cycling. Sulfur facilitates iron redox cycling through homogeneous/heterogeneous routes. Importantly, density functional theory (DFT) calculations identified that coal tailings containing Sv possessed higher adsorption energy for PMS compared to pristine tailings. These discoveries provide novel insights into the resource utilization of coal tailings and environmental pollution remediation.