Pervaporation recovery of [AMIM]Cl during wood dissolution; effect of [AMIM]Cl properties on the membrane performance

This paper presents the stability and performance of a polyvinyl alcohol-TiO2 (Helmholtz-Zentrum Geesthacht, HZG) membrane for removing water from 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) using pervaporation. The impact of the ionic liquid (IL) on the membrane was assessed through the pervaporation of water/n-butanol mixtures (5 wt%/95 wt%) at 60 °C before and after the membrane was in contact with [AMIM]Cl for a period of time (1, 3 and 5 days) and temperature (40, 60 and 80 °C). Response surface methodology was used for the experimental design and result analyzing. The central composite face design yielded empirical models with an excellent fit and predictive power for the responses total flux through the membrane and concentration of water in the permeate. The membrane tolerated the contact with [AMIM]Cl in all the conditions studied. The total flux of components increased up to 3 times with the contact with the IL and 3 to 8 times with the increase in the temperature at which the contact occurred. However, the permeate was more diluted in water. The period of contact affected moderately the responses. Finally, the dehydration of the used [AMIM]Cl at 60 °C showed low water fluxes through the membrane: 9.42×10−7 kgm−2 s−1.