Development of novel membranes for PV separation of water–isopropanol mixtures using poly(vinyl alcohol) and gelatin

• Membrane with 10 mass% of Ge showed excellent performance.
• Ge incorporated PVA membranes showed high Tg value.
• Membranes have lower Epw compared to EpIPA, showing higher separation efficiency.
• M-2 membrane showed negative ΔHs value, suggesting the Langmuir's mode of sorption.

Using a solution technique, crosslinked poly(vinyl alcohol) (PVA) membrane was developed by varying the amounts of gelatin (Ge). Physico-chemical properties of the resulting membranes were studied using Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). After studying the swelling properties at different mass% of water, membranes were subjected to pervaporation separation of water–isopropanol mixtures in a temperature range of 30–50 °C. The experimental results demonstrated that membrane containing 10 mass% of Ge showed the highest separation selectivity of 1791 with a flux of 2.92×10−2 kg/m2 h at 30 °C for 10 mass% of water. The values of total flux and flux of water are found to be almost overlapping, suggesting that the developed membranes could be effectively used to break the azeotropic point of water–isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (Epw) are much lower than those of isopropanol permeation (EpIPA), suggesting that the developed membranes have higher separation efficiency for water–isopropanol system. The estimated Ep and ED values were ranged between 13.65 and 8.35, and 13.85 and 5.23 kJ/mol, respectively. The positive heat of sorption (ΔHS) values was observed in all the membranes (except membrane M-2), indicating that Henry's mode of sorption is predominant.

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