Selective polymerization of chlorophenols in hypersaline wastewater via surface-complex-mediated electron transfer...

Conventional radical-based advanced oxidation processes (AOPs) for chlorophenols (CPs) removal in hypersaline wastewater face critical challenges, including excessive oxidant demand, rapid radical quenching by chloride ions, and toxic chlorinated byproduct formation. Here, we report a nonradical electron transfer (ETP)-driven polymerization strategy that enables complete CPs elimination without mineralization. By employing cerium-doped mesoporous CuO (Ce-CuO) with peroxydisulfate (PDS), 4-chlorophenol (4-CP) was selectively oxidized into phenoxy radicals via a surface-activated Ce-CuO@PDS complex, followed by polymerization into insoluble solid organic polymers. At a low PDS dosage (1.0 mM), 100 % 4-CP (0.78 mM) removal was achieved with 86.4 % total organic carbon (TOC) conversion to polymers. Mechanistic studies confirmed ETP dominance over radical pathways, with interfacial oxygen vacancies (Cu⁺-Ov-Ce³⁺) reducing PDS adsorption energy (vs. pristine CuO) and enhancing electron transfer efficiency. The strategy demonstrated robust performance under hypersaline conditions (Cl^-, 3000-10,000 mg L^-1) and superior selectivity when treating paper mill wastewater. Notably, the system achieved a high decontamination capacity (3.74 g 4-CP per gram catalyst) while consuming 89 % less oxidant than mineralization-based methods. This work establishes a sustainable paradigm for treating refractory organics in high-salinity industrial effluents through ETP-driven polymerization.