P(VDF-co-HFP) membrane for recovery of aroma compounds from aqueous solutions by pervaporation

In this study, poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-co-HFP)) was firstly used as a membrane material in organophilic pervporation for aroma compounds' recovery. Separation and transport properties of P(VDF-co-HFP) coated polypropene (PP) composite membrane in pervaporation of EtAc-water mixture were investigated. The effects of two process conditions (EtAc feed concentration and operating temperature) on pervaporation parameters (permeation flux and separation factor) were discussed in detail. The study shows that acetone-fabricated membranes have excellent mechanical strength, thermal stability and film-forming properties. In addition, they have ideal pervaporation performances compared to commonly used poly(dimethylsixolane) (PDMS) membrane and poly (ether block amide) (PEBA) membrane. Its separation factor is higher than that of PEBA membrane but lower that of PDMS membrane. The permeate flux is relatively high, which depends on not only the nature of the given membrane material but also the membrane-formed special structure and morphology. Mass transports in the membrane were investigated based on the change of microstructure from DSC analysis during the swelling process. The activation energies for permeation of water (EP,W) and EtAc (EP,E) calculated from the slopes of Arrhenius plots of ln(J) versus 1/T were employed to explain the diffusion process. In general, the sorption process dominates the separation mechanism.