Nanosized SiO2-enhanced PDMS membrane for efficient isopropanol-butanol-ethanol (IBE) separation by pervaporation

Abstract

Pervaporation separation of isopropanol-butanol-ethanol (IBE) aqueous mixture was carried out using polydimethylsiloxane (PMDS) membranes containing 5, 10, and 15 wt.% of nanosized SiO2. PDMS/SiO2 membranes prepared by solution-casting technique were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). Sorption experiments were performed at 30 degrees C, 40 degrees C, and 50 degrees C, and the interaction parameters between the pure components and the membrane were calculated. Further, the activity coefficients, excess Gibbs energies, and binary interaction parameters of organic-water binary systems at different temperatures were estimated using the UNIFAC method. A single-component permeation through pristine PDMS and nanocomposite PDMS membranes, as well as the pervaporation separation performance of PDMS-based membranes at different temperatures for a model IBE mixture with a concentration of 20 gL-1, were investigated. The pervaporation results showed that the highest butanol permeability (15514 Barrer) and selectivity (102.6) values were obtained for 5 wt.% and 15 wt.% SiO2-filled PDMS membranes at 30 degrees C, respectively.