Enhanced anti-swelling property and dehumidification performance by sodium alginate–poly(vinyl alcohol)/polysulfone composite hollow fiber membranes

Enhanced membrane dehumidification performance was achieved by physically blending sodium alginate (NaAlg) with poly(vinyl alcohol) (PVA). Both flat-sheet homogenous membranes and hollow-fiber composite membranes were prepared and characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS). When PVA content was 20 wt.% and 30 wt.%, the blend membranes exhibited lower swelling degree and much higher water/propylene selectivity than both NaAlg and PVA control membranes, resulting from the better-controlled free volume cavity size. In particular, the blend membrane containing 20 wt.% PVA showed the best dehumidification performance for propylene-water mixture. Both high water permeance (>10−2 cm3(STP)/cm2 s cmHg) and high selectivity (infinite big) were acquired for 0.13 wt.% water in feed under optimized operating conditions (temperature: 298 K; feed pressure: 250 kPa; feed flowrate: ≥300 ml/min).