Improved organic acid purification through wafer enhanced electrodeionization utilizing ionic liquids

Abstract

Purification of organic acids through electrodialysis has been studied extensively over the past two decades; however, little work has been done on attempting to utilize electrodialysis for solvent replacement for improved acid recovery. This study presents the use of ionic liquids as a secondary electrodialysis solvent in order to transport organic acids from a water phase into an ionic liquid phase. Specifically, the use of wafer enhanced electrodeionization techniques with ionic liquids is investigated to improve system performance. Incorporation of ionic liquids allows continuous separation with high solvent recyclability and low operation hazards. Through the use of wafer technology, current efficiencies reached 37–90% with energy consumption rates of approximately 1.25–2.80kWh/kg acid recovered. Improved separation efficiencies were due to improved electrical conductance of the solutions provided by addition of the resin wafer into the cell compartments. The influence of solution conductivity and current density on separation performance was also studied. It was found that high current densities resulted in higher ion and water transport. Solubility of products, ionic liquid solution characteristics, and water contamination were also found to have a significant impact on current efficiency and power consumption. Through this project, separation of organic acids into ionic liquids with low energy requirements and high separation efficiencies was achieved.