Dual enhancement of hydrophilicity and surface charge for antifouling PVDF membranes via coagulation bath optimization

To address the fouling problem of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes, this study embedded β-cyclodextrin (β-CD) from the coagulation bath into the membrane surface and pore walls via non-solvent induced phase separation, thereby enhancing surface hydrophilicity and negative potential and improving the membrane’s fouling resistance. The results showed that when the coagulation bath temperature was 25 °C, and the β-CD content was 0.5 wt%, the resulting β-CD/PVDF UF membrane exhibited optimal performance. It achieved a water permeance of 570 L·m −2 ·h −1 ·bar −1 and a methyl blue rejection rate of approximately 90%. Introducing β-CD increased the membrane surface roughness and made its pores smaller and more uniformly distributed. The contact angle decreased by 15°, and the surface potential became approximately 10 mV more negative (pH = 7). The β-CD/PVDF UF membrane exhibited a relatively high flux recovery ratio during both dye and bovine serum albumin cyclic filtration processes, indicating its excellent antifouling performance. During a 72 h constant-pressure filtration experiment, the contact angle of the β-CD/PVDF UF membrane remained nearly 65°, indicating good hydrophilic stability. Thus, this approach provides a new method for developing high-performance antifouling PVDF UF membranes with potential applications in textile wastewater treatment.