Description of the pervaporation dehydration performance of A-type zeolite membranes: A modeling approach based on the Maxwell–Stefan theory

The dehydration performance of zeolite NaA membranes was investigated for the pervaporation (PV) of ethanol/water mixtures. High quality zeolite NaA membranes were prepared onto the inner-side of α-alumina tubular supports by the secondary growth method with a cross-flow filtration seeding combined with further semi-continuous hydrothermal syntheses (two cycles). The PV performance of the as-synthesized membranes was explored at 303–363 K for water compositions 1–60 wt.% and for feed and permeate pressures in the range 0–7 bar (relative) and 2–70 mbar, respectively. The selectivity was found to show a maximum at a water feed composition in the range 5–10 wt.% and to rise with temperature. Water and ethanol fluxes were successfully fitted to an adsorption–solution model derived from the Maxwell–Stefan theory, where ethanol flux is coupled with water flux. The adsorption of water and ethanol on the feed/membrane interface appears to govern the PV performance of zeolite NaA membranes.