Correlation between anions of ionic liquids and reduction of silver ions in facilitated olefin transport membranes

The correlation between the anions of the ionic liquids of BMIM+BF4−, BMIM+CF3SO3− and BMIM+NO3− in poly(2-ethyl-2-oxazoline)/AgNO3 membranes and reduction of silver ions has been investigated. The anion type negligibly affected the initial separation performances, however it significantly affected the long-term operation stability. Additionally, UV and TEM confirmed the long-term operational stability was strongly associated with the reduction rate of the silver ions. The reduction rate of the silver ions in the polymer/silver salt/ionic liquid complex was observed in following order: BMIM+BF4− > BMIM+CF3SO3− > BMIM+NO3−, suggesting that among the ionic liquids investigated, BMIM+NO3− had the most improved separation performance.