Construction of high-performance Ce-doped TiO2 tight UF membranes for protein separation

• Monodispersed Ce-Ti colloidal sol was synthesized by modified sol-gel route. • Ce-doping effectively inhibited phase transformation of TiO 2 and therefore improve the membrane integrity and pore structure. • The optimal Ce-doped TiO 2 membranes exhibit higher permeance and lower MWCO compared with pure TiO 2 membranes. • The introduction of Ce helps enhance the membrane surface charge and narrow the pore size distribution, thus improve the membrane antifouling property to BSA. The membrane structure and properties have a significant influence on its anti-fouling performance during the separation process. In this study, Ce was introduced to inhibit the phase transformation of TiO 2 to obtain a tight ultrafiltration (UF) membrane with a more uniform pore size, a more integrated membrane layer as well as to strengthen the membrane surface charge to provide superior anti-fouling performance for the membrane during protein separation. Single anatase phase of the material proves that the introduction of Ce effectively inhibited the phase transformation of TiO 2 and prevented the occurrence of cracks. The prepared Ce-doped TiO 2 membrane exhibited excellent performance, with a membrane thickness of 700 nm, water permeance of 175 L·m -2 ·h -1 ·bar -1 and molecular weight cut-off of approximately 18 kDa. Additionally, it showed excellent BSA separation performance, as the stable permeance and rejection rate could be maintained at 120 L·m -2 ·h -1 ·bar -1 and 100%, respectively. Meanwhile, Ce-doped TiO 2 membrane showed superior anti-fouling performance compared to pure TiO 2 membrane due to its strengthened surface charge and uniform pore size, with the J/J0 maintained a value of 0.69. Based on the obtained results, the Ce-doped TiO 2 membranes prepared in this study exhibit good potential for protein separation.