A new method for tailoring the surface pore size and internal pore structure of ultrafiltration membranes without using additives—Atomization-assisted nonsolvent induced phase separation method

It is highly desired to improve the safety and stability of ultrafiltration (UF) membranes for biotechnology, medicine and food processing by eliminating the use of chemical additives during the membrane preparation process. In this work, a series of high-performance polyacrylonitrile (PAN) UF membranes were prepared continuously by the atomization-assisted nonsolvent induced phase separation (AA-NIPS) method. The pore structure and surface properties of the membranes can be precisely tailored, requiring no chemical additives. The prepared UF membranes are composed of a sublayer of highly interconnected three-dimensional (3D) network structure and a smooth surface layer of uniform small pore structure with a narrow pore size distribution. Compared to UF membranes prepared by the NIPS method, the PAN UF membranes exhibit enhanced water flux and antifouling properties as well as a well-preserved high rejection to bovine serum albumin (BSA). With different atomization pretreatment times, the pure water fluxes of the UF membranes increased by 41 %∼100 %. The AA-NIPS method employed in the present work can effectively modify the porous structure of the membranes without introducing pore-forming additives. The good separation performance, structural controllability, and easy functionalization of the UF membranes make them a promising candidate to be applied in many fields, especially in biotechnology, medicine, and food processing.