摘要
In this work,experiments to examine the recycling of ionic liquids(ILs)from aqueous solution by nanofiltration(NF)were conducted.The influences of pH,ionic strength,and macromolecular organic matter on filtration performance metrics including the volume flux(J_(v))and observed rejection(R_(obs))were systematically studied.Aqueous solutions of three widely studied ILs,specifically 1-butyl-3-methylimidazolium chloride([C_(4)mim]Cl),1-decyl-3-methylimidazolium chloride([C_(10)mim]Cl),and 1-buty 1-3-methylimidazolium tetrafluoroborate([C_(4)mim]BF_(4))were selected for this study.The mechanisms of interaction between the ILs and the NF membrane under different pH and ionic-strength conditions were revealed by quantum chemical calculations and molecular simulations.The results showed that with increasing pH,the J_(v) and R_(obs)values of the[C_(4)mim]Cl and[C_(10)mim]Cl aqueous solutions increased,while for the[C_(4)mim]BF_(4)aqueous solution,the J_(v) value increased and the R_(obs)value decreased.Furthermore,with increasing ionic strength,the J_(v) values of the[C_(4)mim]Cl and[C_(4)mim]BF_(4)aqueous solutions decreased,and their R_(obs)values increased;conversely,for the[C_(10)mim]Cl aqueous solution,the R_(obs)value decreased,and the J_(v) vale first increased and then decreased.In addition,it was found that the presence of macromolecular organic matter tends to cause membrane fouling and has a great influence on the separation of aqueous solutions of ILs by NF.In general,membrane fouling leads to an increase in the R_(obs)value but a decrease in the J_(v) value.
