Pervaporation separation of ethylene glycol/water mixtures through surface crosslinked PVA membranes: Coupling effect and separation performance analysis

Dehydration of ethylene glycol (EG) aqueous solution by pervaporation was studied by surface crosslinked poly(vinyl alcohol) membrane using glutaraldehyde as crosslinking reagent. The membrane shows desirable thermal stability, mechanical stability and pervaporation performance (for 80 wt.% EG aqueous solution at 70 °C, the permeation flux and separation factor are 211 g m−2 h−1 and 933). The remarkable dependence of water and EG concentration in permeate side as well as their activity coefficients within the membrane on feed concentration indicate that a strong coupling effect exists between water and EG, which effectively inhibits the permeation of EG and thus considerably enhances the separation selectivity of membrane. With feed temperature increasing, the permeation flux increases but separation factor decreases significantly due to the difference of activation energies between water and EG. With feed flow rate increasing, both the permeation flux and separation factor increase correspondingly.