This study demonstrates the fabrication of loose nanofiltration (LNF) membranes using polysulfone dissolved in eco-friendly co-solvents (PolarClean and gamma-Valerolactone) via slot die coating (SDC) on a roll-to-roll (R2R) system. Optimal SDC parameters (20 mL/min solution flow rate, 17.1 mm/s substrate speed, 0.1 mm coating gap) produced defect-free membranes. Pre-wetting the support layer improved adhesion and minimized thickness shrinkage. SDC membranes showed performance comparable to bench-scale doctor blade extruded samples, with pre-wetted, uncompressed samples exhibiting 99.20% ± 1.31% bovine serum albumin rejection and adequate permeability (70.5 ± 8.33 LMH/bar). This approach integrates sustainable materials with scalable manufacturing for membrane separations.

David Lu, Kwangjun Jung, Ju Young Shim, Tequila A. L. Harris, Isabel C. Escobar