Fabrication and Characterization of High Performance Polysulfate Hollow Fiber Membranes Achieved With Spongy‐Structure Adjusting of Ionic Liquid

ABSTRACT Polysulfate (PSE) hollow fiber membranes were fabricated by non‐solvent induced phase separation (NIPS), with ionic liquids (IL) integrated to adjust the microstructure for improved membrane permeability and selective performance. The solubility parameters and thermodynamic characterization of the PSE casting solution were determined by turbid point titration, while its kinetic behavior was observed by a rotational rheometer. Ultrafiltration experiments were conducted to investigate the separation performance of the prepared membranes. The morphology and composition of PSE membranes were characterized using scanning electron microscopy (SEM), capillary flow pore size distribution, atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Results indicated that increasing IL concentration in the casting solution initially accelerated the phase separation rate, followed by reduction at higher concentrations. Remarkably, at an optimal IL concentration of 12 wt%, the prepared membrane exhibited a water flux of 134.62 LMH, a BSA retention of 98.52%, a tensile strength of 4.83 MPa, and a surface roughness of 7.93 nm, outperforming membranes prepared with other IL loadings. The proposed PSE hollow fiber membranes highlight the intrinsic mechanisms linking phase separation to the membrane's microstructure manipulation, providing valuable insights for membrane preparation.