Solving the trade-off phenomenon in separation of water–dioxan mixtures by pervaporation through crosslinked sodium–alginate membranes with polystyrene sulfonic acid-co-maleic acid

Polymeric membranes composed of sodium alginate and polystyrene sulfonic acid-co-maleic acid were prepared using a solution technique. The resulting membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Membranes were tested for their ability to separate water–dioxan mixtures in the temperature range of 30–50 °C. The experimental results demonstrated that both flux and separation factor were increased simultaneously with increasing the PSSA-MA content in the membrane. The permeation flux of pure Na-Alg membrane was increased dramatically from 7.1 to 10.6×10−2 kg/m2h with increasing the mass% of PSSA-MA, and correspondingly its separation factor was increased from 6400 to 22,500 at 30 °C for 10 mass% of water in the feed. The total flux and flux of water were found to be overlapping each other particularly for crosslinked membranes, suggesting that these membranes could be used effectively to break the azeotropic point of water–dioxan mixture. From the temperature dependent permeation values, the Arrhenius activation parameters were estimated.

Synthesis of crosslinked Na-Alg/PSSA-MA membrane.Figure optionsDownload high-quality image (72 K)Download as PowerPoint slideHighlights
► PSSA-MA incorporated membranes overcome a trade-off phenomenon.
► Total flux and flux of water are overlapping, indicating the higher selectivity.
► Membrane containing 75 mass% of PSSA-MA exhibited the highest separation factor.
► Membranes demonstrated higher separation ability towards water.