Pervaporation separation of dimethyl carbonate/methanol mixtures with regenerated perfluoro-ion-exchange membranes in chlor-alkali industry

摘要

The waste perfluoro-ion-exchange membranes (PFIEMs) in chlor-alkali industry were regenerated and used to the separation of dimethyl carbonate (DMC)/methanol (MeOH) mixtures by pervaporation process. The energy-dispersive spectrum (EDS) demonstrates that the impurities on the surfaces of waste PFIEMs can be effectively cleared by the regeneration process. The degree of swelling, sorption, and pervaporation properties of the regenerated PFIEMs with different counter ions were investigated. The results indicate that the counter ions of PFIEMs conspicuously influence the degree of swelling, sorption, and pervaporation properties for DMC/MeOH mixtures. The degree of swelling and solubility selectivity both decreases with the alkali metal counter ions in the sequence: Li~+ > Na~+ > K~+ > Cs ~+. The degree of swelling increases with MeOH concentration increasing in feed liquid. The pervaporation measurements illustrate that the permeation flux decreases and the separation factor increases with the rising in ion radius of counter ions. The increase of feed concentration (MeOH) and feed temperature is advantageous to improve permeation flux while at the cost of separation factor decreasing.