Insights into the permeability and anti-pollution mechanism of FeCo/BC@PVDF ultrafiltration membrane in-situ coupled PMS purification fluorine-containing wastewater

Polyvinylidene fluoride (PVDF) membrane filtration is extensively employed in the treatment of fluoride-containing wastewater due to low cost and operational simplicity. However, it still faces the challenges of unsatisfactory permeability and anti-pollution performance. In the present work, a novel PVDF ultrafiltration membrane modified with FeCo/BC (FeCo/BC@PVDF) that exhibits outstanding catalytic activity was fabricated via the non-solvent-induced phase separation (NIPS) method, which further enables the in-situ coupling between the as-fabricated membrane and peroxymonosulfate (PMS). The performance evaluation exhibits that the pure water flux and rejection rate of FeCo/BC@PVDF ultrafiltration membrane increased from 235.91 L⋅m −2 ⋅h −1 and 51.63 % to 445.61 L⋅m −2 ⋅h −1 and 90.71 %, and the irreversible pollution rate has decreased from 37.69 % to 17.67 % in in-situ coupling PMS systems. Meanwhile, the characterization results of XRD, FTIR, SEM, XPS and water contact angle (WCA) confirmed that the outstanding permeability and anti-pollution performance were attributed to good pore distribution, hydrophilicity and catalytic performance. In addition, the pollution model fitting, extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and heterogeneous experiments were used to further understand the anti-pollution mechanism of FeCo/BC@PVDF, and the results reveal that pollution mode of ultrafiltration membrane has changed from multiple contamination behaviors to easily rinsed cake layer contamination because of the in-situ degradation effect of SO₄⁻•, O₂⁻• and •OH on sodium p-perfluorous nonenoxybenzenesulfonate (OBS). This research provides a new idea for simultaneously improving the permeability and anti-pollution performance of PVDF ultrafiltration membranes in the field of fluorine-containing wastewater treatment.