Experimental Investigation on Glutaric Acid Reactive Separation Using Tri-n-butyl Phosphate in Octanol and Oleyl Alcohol at 298 ± 1 K

Abstract

Glutaric acid is a fundamental precursor in a wide range of pharmaceuticals and functional chemicals. Reactive separation offers a more efficient recovery method compared to traditional techniques such as electrodialysis, distillation, and membrane separation. In this work, tri-n-butyl phosphate (TBP) at different concentrations (10–50 vol %) in oleyl alcohol and octanol is used for the reactive separation of glutaric acid (0.195 to 1.133 mol kg^–1) at 298 ± 1 K under atmospheric pressure. Key extraction process parameters, including extraction efficiency (E%), distribution coefficient (K_D), loading ratio (z), and equilibrium complexation constant (K_E), were examined. Oleyl alcohol outperformed octanol, resulting in a K_D of 8.77 and an extraction efficiency of 84.76% at a TBP concentration of 3.624 mol·kg^–1. Process design parameters, including the minimal ratio of solvent-to-feed and the number of theoretical stages, were estimated for liquid–liquid extraction column design. Equilibrium characteristics were analyzed using the mass action law, relative basicity, linear solvation energy relationship (LSER), and the Langmuir model. The relative basicity model provided the closest fit to experimental data, with an error margin under 5%. The findings offer detailed insights into equilibrium characteristics and contribute to the development of efficient reactive extraction systems for glutaric acid.