Insights into 1-butyl-3-methylimidazolium hydrogen sulfate recovery from wastewater by electrodialysis with heterogeneous ion-exchange membranes

Abstract

Abstract Due to the negative impact of ionic liquids (ILs) on the environment and their high cost, it is very important to examine their recovery and recycling methods. Thus, in this study, research on 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) recovery from wastewater by electrodialysis (ED) is presented. The influence of the initial [Bmim]HSO4 concentration, the voltage, and the linear flow velocity on the effective [Bmim]HSO4 recovery was examined. To assess the effectiveness of the proposed method, factors such as IL percentage recovery, degree of concentration, electric current efficiency, and energy consumption were determined. It was found that as the initial concentration of [Bmim]HSO4 in the feed solution increased from 0.01 to 0.2 M, the [Bmim]HSO4 recovery efficiency increased. A 2.3-fold concentration of the [Bmim]HSO4 in the concentrate solution with a recovery of 98.8%, a current efficiency of 67.3%, and energy consumption of 28 kWh/m3 was achieved for ED of a 0.2 M [Bmim]HSO4 solution using heterogeneous ion-exchange membranes. Additionally, the voltage and linear flow velocity affected the [Bmim]HSO4 recovery. The highest ED efficiency for the recovery and concentration of [Bmim]HSO4 was obtained at an applied potential of 4 V, a 2 cm/s linear flow velocity, and 0.2 M IL in the feed solution.