Polymer Bulletin, Vol.73, No.3, 743-762, 2016
Development of novel alginate-silica hybrid membranes for pervaporation dehydration of isopropanol
Using a sol-gel technique, organic-inorganic hybrid membranes were prepared by incorporating silica precursors into alginate matrix. Alginate was used as a starting organic polymer, whereas 3-aminopropyl triethoxysilane was used as a counter cation and precursor for the development of inorganic phase. The content of silica gel was controlled by the further addition of tetraethoxysilane (TEOS). The resulting membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. After measuring the swelling data at different mass% of water, membranes were subjected for the pervaporation separation of water-isopropanol mixtures in a temperature range of 30-60 A degrees C. The experimental results demonstrated that membrane containing 30 mass% of TEOS showed the highest separation factor of 17,253 with flux of 4.42 x 10(-2) kg/m(2) h at 30 A degrees C for 5 mass% of water. Except in pure alginate membrane, the values of total flux and flux of water are found to be almost overlapping, suggesting that the developed hybrid 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 estimated E (p) and E (D) values were ranged between 27.84 and 32.63, and 26.98 and 31.28 kJ/mol, respectively. The positive heat of sorption (a dagger H (s)) values was observed in all the membranes, indicating that Henry's mode of sorption is predominant.