Preparation and characterization of ZSM-5/PDMS hybrid pervaporation membranes: Laboratory results and pilot-scale performance

Abstract ZSM-5 zeolites/Polydimethylsiloxane (PDMS) hybrid membranes were prepared and subsequently applied in ethanol recovery from an ethanol-water mixture by pervaporation (PV) using a pilot-plant with spiral-wound membrane module. The influences of calcination temperature on PV performances as well as zeolites properties were studied. Meanwhile, the optimum zeolites loading was turned out to be 30 wt%, the SEM indicated that ZSM-5/PDMS was coated uniformly on the surface of porous PVDF substrate, and the separation layer was dense with the thickness of 8.9 μm. The effects of feed temperature and feed flow velocity on the performance of the pilot-scale PV system were investigated. It was found that with increasing feed temperature, the permeation flux increased, whereas the separation factor firstly increased, then it decreased rapidly. As the feed flow velocity increased, both the permeation flux and separation factor increased. Under the optimum process conditions, the pilot-plant showed a total flux of 1170 g/m² h with ethanol concentration of 60.00 wt% at a feed temperature of 60 °C, a feed flow velocity of 3.2 cm/s and a permeation side pressure of about 2300 Pa with a feed concentration of 10.0 wt% ethanol. A long term run consisted of 1000 h of continuous PV experiments exhibited satisfying performance stability, indicating that the pilot-plant was a promising approach to separate ethanol from ethanol-water mixture and had long-term stability required for industrial application.