Synthesis and characterization of sulfonated-poly(vinyl alcohol) membranes for the pervaporation dehydration of isopropanol

Abstract

Using a solution technique, sulfonated-poly(vinyl alcohol) membranes were developed as pervaporation membranes by incorporating sulfophthalic acid (SPTA). The physico-chemical properties of the resulting membranes were studied by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The mechanical properties of the membranes were studied using universal tensile machine (UTM). Membranes were tested for their ability to separate water–isopropanol mixtures by pervaporation in the temperature range of 40–60 °C. The experimental results demonstrated that the membrane containing 15 mass% of SPTA showed the highest separation selectivity of 3452 with a flux of 3.51 × 10 −2 kg/m 2 h at 40 °C for 10 mass% of water in the feed. The total flux and flux of water were found to be almost overlapping for sulfonated-poly(vinyl alcohol) (SPVA) membranes, suggesting that these could be used effectively to separate the water–isopropanol mixtures. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated and discussed in terms of membranes efficiency. The activation energy values obtained for water permeation ( E pw) were significantly lower than those of isopropanol permeation ( E DIPA), suggesting that the developed membranes have higher separation efficiency for water–isopropanol system. The negative heat of sorption (Δ H S) values was obtained for all the membranes, indicating that Langmuir's mode of sorption is predominant in the process.