Sodium persulfate based PVDF membrane for concurrent advanced oxidation and ultrafiltration of ofloxacin in water

- A novel method for preparing inorganic-organic composite membrane is proposed.
- Combining the filtration and oxidation of membrane may enhance pollutant removal.
- Positively charged and hydrophilic property of DMAEMA is explored in membrane modification.
- Concurrent sulfate radical oxidation and PVDF ultrafiltration is investigated in MCR.

Flat Na2S2O8@PVDF-g-PDMAEMA/PVDF inorganic-organic composite membrane was prepared by sequential use of atom transfer radical polymerization (ATRP), non-solvent induced phase inversion separation (NIPS) and post-dipping treatment. The membrane was tested in a membrane chemical reactor (MCR) system for concurrent advanced oxidation and ultrafiltration of ofloxacin (OFLX) under UV irradiation. Results indicated that the production of sulfate radicals (SO4−) from persulfate can achieve 54% removal efficiency of OFLX, outperforming single advanced oxidation processes (AOPs) or ultrafiltration treatment. The best performance, was secondary to the combination of high redox potential of the SO4−, hydrophilicity of N,N-dimethylaminoethyl methacrylate (DMAEMA) and molecular cutoff of polyvinylidene fluoride (PVDF) ultrafiltration membrane. This study also identified factors related to successfully preparing composite membranes with concurrent positive charges and hydrophilicity. Characterization using XRD, FTIR and EDS showed that introducing PDMAEMA into the polymer mixture and post-dipping were both required to obtain a multifunctional membrane, which can electrostatically attract negative S2O82− species. Judging from SEM results, the formation mechanisms of the composite membrane structure were derived from instantaneous liquid-liquid demixing.

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