Evaluation of the efficiency of reactive extraction of malic acid using TPA or TOPO in imidazolium-based ionic liquid or conventional solvents

Abstract

Malic acid (H₂mA), which is one of the dicarboxylic acids, plays a vital role in the food industry. In this extraction study, the separation of malic acid from its aqueous medium using an effective solvent-extractant mixture was investigated. This article aims to emphasize the efficacy of ionic liquids (IL), which are green solvents especially 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆) against conventional solvents. Some of these solvents are methyl isobutyl ketone (MIBK), toluene, cyclohexyl acetate (CHA), 1-decanol, dimethyl phthalate (DMP). Tri-n-propylamine (TPA) and tri-n-octylphosphine oxide (TOPO) were used as extractants in the experiments. The distribution coefficient (D), extraction efficiency (E%), and loading factor (Z) were calculated. In the physical extraction experiments, the extraction efficiency was observed to be in the range of 43.30–47.67 %. The reactive extraction results showed that high extraction efficiency was obtained with organic phases prepared with TPA and diluent. The extraction efficiency reached around 99 % at a TPA concentration of 1.78 mol.L⁻¹ in MIBK. Although the results with conventional solvents and BMIM-PF₆ are close to each other, it can be stated that the high regeneration capacity and low volatility of ionic liquids may be the reason for preference compared to conventional solvents.