Preparation and properties of cross-linking PEEKWC/PEI ultrafiltration membrane enhanced by silica and silane coupling agent

Based on previous studies, we prepared ultrafiltration membranes by cross-linking PEEKWC/PEI using a non-solvent induced phase separation method, this membrane has excellent hydrophilicity. We also incorporated silica (SiO₂) into the cross-linked membrane system through distribution blending in this study. The membranes underwent characterization using various methods including SEM, ATR-FTIR, and water contact angle tests. To assess the impact of silica addition on membrane performance, tests were conducted on pure water flux, dye flux, dye retention, salt solution flux, salt-dye mixed solution flux, and retention. The results indicated a noticeable improvement in the hydrophilicity of the membrane following the addition of silica, as evidenced by a reduction in the hydrophilic angle from 22.175° to 6.271°, pure water flux up to 850 LMH at 0.3 MPa. Moreover, the retention performance of the membrane was enhanced, with the Congo red solution reaching a retention rate of 99.9% at 0.3 MPa pressure. Subsequently, a fixed silica ratio was chosen (2wt%), and different ratios of silane coupling agent were added using the distribution blending method to explore their effects on membrane performance. The tests revealed an improvement in the retention performance, the group with the largest change in the Congo Red cut-off rate, with an increase in the Congo Red cut-off from 88.7% to 97.9%.