Hydrophilic poly(phenylene sulfone) membranes for ultrafiltration


Poly(alkylene oxide) based tri- and multiblock oligomers with hydrophobic poly(phenylene sulfone) blocks were evaluated as dope solution additives used for preparation of improved poly(phenylene sulfone) (PPSU) flat sheet (FS) and single bore (SB) ultrafiltration membranes by non-solvent induced phase separation (NIPS). Identical polymer dope recipes were used in both of FS membrane preparation and SB fiber spinning processes. PPSU membranes modified with 9.2 wt % Pluronic® F127 based additive, M2 (7.5 kDa PPSU/ Pluronic® F127), or Lutensol® AT80 based additive, T2 (7.5 kDa PPSU/ Lutensol® AT80), displayed compared to pristine PPSU membranes elevated hydraulic permeance ranging from 485 to 674 kg m−2 bar-1h−1 (pristine PPSU: 310 – 464 kg m−2 bar-1h−1), higher molecular weight cut-off values from 37.0 to 53.5 kDa (pristine PPSU: 21.4 – 23.7 kDa), lower contact angles of 46.4° and 49.8° (pristine PPSU: 86.7°) and reduced fouling propensity with irreversible fouling values of 10 % (pristine PPSU: 15 %) for diluted potting soil extract as model substance. The combined analysis methods of X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance spectroscopy (1H NMR) indicated modest surface enrichment of the additives in the filtration layer. Consequently, PPSU ultrafiltration membranes modified with additives T2 and M2 provide interesting alternatives to poly(ether sulfone) (PESU) and poly(vinylidene fluoride) (PVDF) based membranes for surface water filtration combining both excellent filtration characteristics with a long lifetime due to its higher chemical resistance.
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