Pervaporation of dichloromethane-cyclopentane and methylal-cyclopentane mixtures through membranes from chloroprene rubber

Chloroprene rubber (CR) has been commonly applied in various branches of the industry but its application in selective layers of pervaporation membranes remains overseen. To survey its applicability, we report on the pervaporation of two close-boiling azeotrope-forming systems of common solvents, blowing agents, adjuvants, and refrigerants, namely, dichloromethane-cyclopentane (DCM-CP) and methylal-cyclopentane (ML-CP). Vulcanizates having the form of thin films (66 +/- 5 mu m) have been prepared from the crystallization-resistant (WRT) polychloroprene by using nanoparticles of ZnO and MgO. Mechanical and thermal properties have been characterized using dynamic mechanical analysis (DMA) and thermogravimetry analysis, spectral properties using ATR-FTIR. Plasticization has been assessed by measuring DMA characteristics for the CR films exposed to vapors of the studied compounds. The CR films are preferentially permeable to DCM and ML over CP, break the respective azeotropes, and show comparable selectivity ranging from 1.1 to 1.7 for DCM-CP and from 1.0 to 1.8 for ML-CP. Importantly, plasticization of the CR membranes by DCM and ML enhances the selectivity and, simultaneously, the transmembrane flux. Overall, we show that membranes from CR enable selective and intensive pervaporative recovery of halogenated hydrocarbons from their mixtures with hydrocarbons, which is relevant, for instance, for the recycling of blowing agents.

Automated summary

The study demonstrates that chloroprene rubber membranes exhibit higher permeability to dichloromethane and methylal than cyclopentane, showing higher selectivity. Moreover, chloroprene rubber membranes plasticized by dichloromethane and methylal not only enhance selectivity but also increase transmembrane flux.