ABSTRACT
Polyvinyl alcohol–polyacrylamide interpenetrating polymer network (PVA-PAAM IPN) membranes, both unsupported and supported on polyethersulfone (PESF) ultrafiltration membranes, were prepared and investigated regarding the pervaporation of water–ethanol mixtures. Compared to the crosslinked polyvinyl alcohol membranes, the PVA-PAAM IPN membranes exhibit improved thermostability, mechanical properties and selectivity. 244The PVA-PAAM IPN membranes were synthesized by the sequential IPN technique. The thicknesses of the unsupported membranes were in the range 30–40 μm, those of the supported ones were about 4 μm, and that of the PESF membrane was 90 μm. The selection of the compositions of the PVA-PAAM IPN layer of the supported membranes was made by examining the pervaporation performance of the unsupported ones. Furthermore, the effects of the feed composition, feed temperature and operating time on the performance of the PVA-PAAM IPN supported membrane was investigated. Depending on the feed composition and temperature, the supported membranes had separation factors between 30 and 28,300 and permeation rates between 30 and 3800 g/(m2 h). High selectivities were obtained at high ethanol concentrations. For the azeotropic water–ethanol mixture (95 wt% ethanol), the supported membrane had at 60°C a separation factor of 13,000 and a permeation rate of 80 g/(m2 h). Compared to the unsupported membranes, the supported ones had a higher permeability but a somewhat lower selectivity.
