The Effect of Process Parameters on the Pervaporation of Alcohols through Organophilic Membranes

Abstract

Several organophilic membranes were utilized to selectively permeate ethanol, n-butanol, and t-butanol from dilute aqueous mixtures using pervaporation (PV). Poly1-(trimethylsilyl)-1-propyne] (PTMSP) membranes were utilized to investigate the effect of temperature, pressure, and start-up/transient time on the separation of aqueous ethanol mixtures. Results indicate optimal ethanol selectivity and flux at the lowest permeate-side pressure. Increased temperature significantly enhanced the productivity of PTMSP, but extended operation of the PTMSP membranes at high temperatures resulted in flux degradation. Two other hydrophobic membranes, poly(dimethyl siloxane) (PDMS) and a poly(methoxy siloxane) (PMS) composite, were used to separate n-butanol and t-butanol from dilute aqueous mixtures. The effect of feed concentration on the flux and selectivity was investigated. Both membranes were found to be more permeable to n-butanol than t-butanol. The PDMS membrane was found to be more effective than the PMS membrane in terms of flux and selectivity. The effect of membrane thickness on water permeation and on organic selectivity was also studied using the PDMS membrane.