Pervaporation Separation of MeOH/MTBE Mixtures with Modified PEEK Membrane: Effect of Operating Conditions

Modified poly(ether ether ketone) (PEEKWC) dense membranes were prepared using chloroform as the evaporating solvent. Pervaporation of methanol (MeOH) and methyl tert-butyl ether (MTBE) mixtures were carried out at different feed concentrations, flow rates and temperatures. The swelling and mechanical properties of the membranes were studied at different MeOH concentrations. These MeOH selective membranes were mechanically strong for PV tests. However, their strength decreased in feed mixture to some extent particularly in contact with high concentrations of MeOH. The observed high separation factor of more than 250 at 1 wt% MeOH dropped to an ultimate value of 4–6 at around 20–50 wt% MeOH. Meanwhile, total permeation flux increased tenfold continuously from 0.015 kg/m2 h to 0.113 kg/m2 h at 87.2 wt% MeOH in feed. Increasing the feed flow rate had a positive effect on both the separation factor and the permeation flux due to the elimination of concentration and temperature polarization. Increasing the feed temperature improved the permeation rate as well. However, the separation factors slightly decreased at higher temperatures. The observed effects of feed temperature on the PV results are caused by increasing the thermal motions of polymer chains and permeating molecules at higher temperatures.