Effective and Low-Toxicity: A Membrane Cleaning Method Using Peroxymonosulfate Catalytic Chlorination

Abstract

In this study, the combined system of peroxymonosulfate and chloride (PMS/Cl−) was applied to chemically clean the irreversible humic acid-fouled polyethersulfone (PES) membranes. A 94% flux recovery and 96% resistance removal of the fouled membrane were reached after soaking for an hour in PMS/Cl− solution (10 mM/15 mM) at 25 oC under neutral conditions. The almost constant surface properties of virgin and cleaned membranes by characterization indicate the PMS/Cl− process can effectively remove irreversible foulants with minimal impact on membrane. The stability and durability of PMS/Cl− cleaned membranes were demonstrated by monitoring their separation performance and cleaning efficiency across multiple cycles. Diminution of the peaks centered in the region of fulvic-like and humic-like components, monitored under 3D-fluorescence, demonstrated that structural changes in hydrophobic substances dominated the foulant detachment. The presence of the PMS-catalyzed chlorination of the foulants was confirmed after detecting PMS and hypochlorous acid (HClO) concentrations in the combined system. Furthermore, lower toxicity was observed with the PMS/Cl− method compared to hypochlorite alone, as evidenced by monitoring halogenated by-product formation and acute toxicity. Overall, the novel chemical cleaning system exhibits promising prospects for the environmentally friendly removal of irreversible organic foulants in the practical water treatment process.

Keywords: Chemical cleaning, Peroxymonosulfate, chloride, humic acid, halogenated by-product