Novel green PVA-fullerenol mixed matrix supported membranes for separating water-THF mixtures by pervaporation
This study focuses first on the preparation of mixed matrix supported membranes of polyvinyl alcohol (PVA) and low-hydroxylated fullerenol C60(OH)12 used to create water selective membranes and then on their pervaporation properties for the separation of water-THF mixtures. These novel supported PVA membranes containing nano-carbon particles were prepared to reach high membrane performance for further integration in a dehydration process, such as distillation coupled to pervaporation. The separation of water-THF mixtures was performed with the supported membranes over a wide range of water concentrations in the feed mixture, i.e., from the azeotrope range up to 30 wt%, to evaluate the performance and stability of the thin active layer. SEM was used to visualize the internal morphology of the membrane. The influence of temperature on the transport properties was also investigated. All the membranes were highly water selective and stable up to 30 wt% water in the feed. The best compromise of transport properties was obtained for the C60(OH)12(5%)-PVA supported composite membrane: a permeate enrichment of 99.3 ± 0.3 wt% water and a flux of 0.25 ± 0.02 kg/(m2 h) for the separation of a mixture containing 5.7 wt% water and 94.3 wt% tetrahydrofuran (THF) at 30 °C. Considering its water stability, this supported membrane with a dense layer thinner than 2 μm appears promising for use in hybrid industrial processes to upgrade solvents with a smaller environmental footprint than conventional methods.