Efficient degradation of Rhodamine B by visible-light-driven biomimetic Fe(III) complex/peroxymonosulfate system: The key role of FeV=O

Advanced oxidation systems (AOS) hold promise for tackling refractory dyes in wastewater, yet the quest for efficient systems tailored to the degradation of dye remains a formidable hurdle. Here, a novel visible-light-driven AOS, consisting of biomimetic Fe(III) salen complex (FeL, salen= N, N-bis(salicylidene)ethylenediamine) and peroxymonosulfate (PMS), was proposed for highly efficient degradation of Rhodamine B (RhB), a model dye. The proposed AOS was capable of degrading 94.8 % RhB in 40 min, outperforming the typical Fe 3+ -based system, which achieved only 52.6 % pollutant degradation under identical conditions. As indicated by experimental results and theoretical calculations, the unique Fe-N 2 O 2 coordination structure of FeL facilitated the adsorption of terminal O (O3) at PMS site, thereby enhancing the heterolysis of the O-O bond and generating high-valent iron-oxo species (i.e., Fe Ⅴ =O) rather than radicals (SO 4 •− , HO • ). The system demonstrated robust resistance to interference from environmental anions (Cl − , NO 3 − , HCO 3 − , SO 4 2− ), pH variations (initial pH 3.0–11.0) and humic acid . More attractively, it achieved 87.3 % chroma and 37.6 % chemical oxygen demand (COD) removal in real dye wastewater samples. This work may shed light on the understanding and development of biomimetic Fe complexes-based AOS for wastewater treatment .