Highly stable polysulfone solvent resistant nanofiltration membranes with internal cross-linking networks

Abstract

Polysulfone based solvent resistant nanofiltration membranes with internal cross-linking networks are designed and fabricated. The internal cross-linking networks are constructed by reacting imidazole with chloromethylated polysulfone (CMPSF). The cross-linking networks can dramatically improve the solvent stability of the polysulfone membranes and the performance of the membrane is tuned via changing the polymer concentration from 20 wt% to 28 wt%. The weight of the cross-linked membranes has barely changed even after immersing them in N,N-dimethylacetamide (DMAc) for more than 96 h, exhibiting superior stability in apolar solvents. The separation performance of the cross-linked PSF membranes is investigated via filtration experiments, where three dyes, crystal violet (CV), bromothymol blue (BTB) and rose bengale (RB) with different MW and different charge properties are selected as solutes. It is found that with increasing polymer concentration, an increased rejection and a decreased flux are observed. The prepared cross-linked membranes showed good selectivity on dyes with different molecular weights in different solvents (yielding more than 99% retention for RB in apolar DMAc) coupled with remarkable stability, exhibiting very good prospects in SRNF application.