Co²⁺/PMS based sulfate-radical treatment for effective mineralization of spent ion exchange resin

Sulfate radical advance oxidation processes (SR-AOPs) have attracted a greater attention as a suitable alternative of the hydroxyl radical based advance oxidation process (HR-AOPs). In this study, for the first time we report liquid phase mineralization of nuclear grade cationic IRN-77 resin in Co²⁺/peroxymonosulfate (PMS) based SR-AOPs. After the dissolution of cationic IRN-77 resin, 30 volatile and 15 semi-volatile organic compounds were analyzed/detected using non-targeted GC-MS analysis. The optimal reaction parameters for the highest chemical oxygen demand (COD) removal (%) of IRN-77 resin were determined, and the initial pH, PMS dosage, and reaction temperature were found to be the most influential parameters for the resin degradation. We successfully achieved ∼90% COD removal (1000 mg/L; 1000 ppm) of dissolved spent resin for SR-AOPs by optimizing the reaction parameters as initial pH = 9, Co²⁺ = 4 mM (catalyst), PMS = 60 mM (as oxidant) at 60 °C temperature for 60 min reaction. The electron spin resonance spectroscopy (ESR) spectra confirmed the presence of SO₄^∙- and OH^∙ as main reactive species in the Co²⁺/PMS resin system. In addition, Fourier transform infrared spectroscopy (FT-IR) analyses were used for structural characterization of solid and liquid phase resin samples. We believe that this work will offer a robust approach for the effective treatment of spent resin generated from nuclear industry.