High-Flux Fine Hollow Fiber Nanofiltration Membranes for the Purification of Drinking Water

High-flux fine hollow fiber nanofiltration (HFNF) membranes were prepared by interfacial polymerization (IP) using polysulfone (PSF) ultrafiltration (UF) membranes with an outer diameter of 425 μm as the substrate for the treatment of drinking water. Trimesoyl chloride (TMC) was selected as the organic phase monomer, while poly­(vinyl alcohol) (PVA) was added into piperazine (PIP) aqueous phase solution to reduce the surface defects and to enhance the separation performance of the NF membrane. The as-prepared fine HFNF membranes had a large packing density and effective area. The optimal preparation conditions of the fine HFNF membrane were determined by orthogonal experiments in which the flux of the membrane reached 34.2 ± 1.5 L·m^–2·h^–1·bar^–1, while its salt rejection sequence was as follows: Na₂SO₄ (97.6 ± 1.5%) > MgSO₄ (96.1 ± 1.8%) > MgCl₂ (83.5 ± 2.1%) > NaCl (27.9 ± 2.6%). During the long-term stability test for 132 h, the membrane retained a high flux (>23.7 ± 1.5 L·m^–2·h^–1·bar^–1) and high Na₂SO₄ rejection (>97.2 ± 1.1%). Additionally, it exhibited huge potential for application in drinking water purification in which the as-prepared NF membrane exhibited excellent antifouling performance for bovine serum albumin (BSA).