Regulating the morphological structure of cellulose acetate ultrafiltration membrane by adjusting the ratio of N, N-dimethylacetamide: N-methyl pyrrolidone in co-solvent to enhance separation and anti-fouling performance

Cellulose acetate (CA) has attracted much attention in the preparation of ultrafiltration membranes due to its green and sustainable characteristics. However, its poor performance (separation and antifouling performance, etc.) limits the application of CA-based membranes in water treatment. In this work, we prepared a cellulose acetate ultrafiltration membrane with enhanced separation performance by enhancing the dissolution process of CA. The dissolution process of CA was controlled by adjusting the ratio of mixed solvent ( N , N -dimethylacetamide (DMAC) and N -methyl pyrrolidone (NMP)), which could tune the phase conversion rate, optimizing the pore structures of the membranes. Compared to the single solvent (M0, M8), the optimal membrane (M4) exhibited a finger-like pore structure and the lowest surface roughness, which was favorable for achieving high water flux. As a result, the M4 possessed a comparable pure water flux (335.8 L·m −2  h −1 ) which was higher than M0 (1.8 times) and M8 (1.7 times), while the BSA rejection rate reached 96.4 %. Besides, the M4 showed a stable separation performance in different operation pressures, BSA concentration, and long-term experiments. This work provided a new method for the preparation of cellulose acetate ultrafiltration membrane with good separation performance and anti-fouling performance and also provides a new way for water treatment.