Removal of tetrahydrofuran (THF) from water by pervaporation using homo and blend polymeric membranes

Pervaporation (PV) membranes have been made from some homopolymers like unplasticized polyvinyl chloride (UPVC), plasticized PVC (PPVC), polystyrene (PSTY) and blends of UPVC and PSTY in different compositions. The morphology of the blend membranes was characterized by scanning electron microscopy (SEM). Sorption and pervaporation of tetrahydrofuran (THF) with different concentrations (0.44-11.3 wt.%) in water were studied under various conditions like feed concentration, temperature etc. Permeation factor and activation energy as a function of feed concentration were also studied in this work. For 0.44 wt.% of THF in feed at 30 °C the used membranes were found to show the following trend of flux i.e. PPVC(13.18 g/m² h) > PSTY(10.38 g/m² h) > Blend-5(8.51 g/m² h) > UPVC(4.79 g/m² h) while separation factor showed the opposite trend i.e. UPVC(170.28) > Blend-5(127.80)> PSTY(89.81)> PPVC-5(81.65). UPVC with its close packed structure showed highest separation factor while presence of polar DOP loosen its matrix and thus, UPVC showed highest flux. PSTY contains some free void space because of its aromatacity and showed lower selectivity than Blend-5 membrane. Among the various blend membranes, THF selectivity decreases while flux increases with increasing amount of PSTY and Blend-5 containing 5 wt.% styrene showed good balance of flux and selectivity.