Bioinspired hierarchical electrospun TiO₂/BiOI nanofibers for multifunctional photocatalytic PMS activation: Antibiotics and microplastics removal

Abstract

Emerging antibiotics and microplastics are poorly removed by conventional treatment processes, requiring oxidation processes that address both dissolved and particulate contaminants. Hierarchical electrospun TiO2/BiOI nanofibers (TBO1–TBO4; BiOI growth 2–16 h) were engineered for photocatalytic peroxymonosulfate (PMS) activation under UV-A (365 nm) and visible light. At pH 7 and 20 °C (sulfamethoxazole, SMX, 5 ppm; catalyst 0.50 g L−1; PMS 2.5 mM), TBO3 achieved near-complete, blank-corrected total organic carbon (TOC) removal (≥99%) in 120 min under visible light + PMS. For a four-component multipollutant solution (20 ppm total), TBO3 reached near-complete TOC removal after blank correction (reported as ≥99%, with residual TOC close to the method quantification limit) in 120 min and maintained activity over nine cycles under visible light + PMS (≤0.7 %age-point change; leaching below detection), whereas UV-A + PMS decreased to 85.3% by cycle 9 with ppb-level leaching. Quenching and probe assays indicate a radical-accessible PMS-assisted oxidation network; strong suppression by tert-butanol and methanol supports major •OH-accessible oxidation with a sulfate-radical-type contribution. Under visible light (465–470 nm) + PMS, cross-linked polystyrene (PS) microplastics (20 ppm solids) underwent surface erosion, cracking, delamination, and fragmentation, accompanied by release of dissolved/sub-10 μm carbonaceous products in scaled-up tests, supporting partial oxidative transformation of particulate microplastics.