A continuous-flow catalytic process with natural hematite-alginate beads for effective water decontamination and disinfection: Peroxymonosulfate activation leading to dominant sulfate radical and minor non-radical pathways

A natural, ferruginous material, Hormuz Red Soil (HRS), was used as a catalyst for decontamination and disinfection via PMS activation. The HRS was fully characterized (morphological, structural, chemical properties) and was mainly comprised of α-Fe2O3. Complete degradation and 88.6% mineralization of Diclofenac (DCF) was achieved in the HRS/PMS process (10 mg/L HRS, 75 mg/L PMS) within 8 min at neutral pH, while sulfate and chloride did not inhibit the process. E. coli and Enterococcus sp. were rapidly inactivated in shorter timeframe than DCF. The rapid purification was attributed to SO4∙-, less to 1O2 and almost insignificant HO∙ participation; the degradation mechanisms and transformation pathways were fully elucidated by scavenging tests/EPR, and LC/MS, respectively. Considering potential applications, HRS was supported on alginate beads (HRSB), maintaining high activity and high reusability (x5 reuse). Finally, a continuous-flow, packed-bed process with HRSB/PMS was assessed, where DCF degradation and mineralization was reached within 2 min HRT.