Modeling and Optimization of Reactive Extraction of Citric Acid

TLDR

The study examined reactive extraction of citric acid from dilute aqueous solutions using TBP, TOA, and A336 in butyl acetate, decanol, and benzene, performing isothermal batch equilibrium experiments at 300.15 K and optimizing complex stoichiometry with differential evolution. Maximum extraction efficiency of 95.5 % was achieved with 20 % TOA in butyl acetate, and the linear solvation energy relationship model accurately predicted distribution coefficients, with experimental and model values closely matching, while FTIR confirmed amine overloading in the citric acid–TOA–decanol system.

Abstract

Reactive extraction of citric acid from dilute aqueous solutions was studied using three different extractants, namely tri-n-butylphosphate (TBP), tri-n-octylamine (TOA), and Aliquat 336 (A336), dissolved in three different diluents: butyl acetate, decanol, and benzene. The isothermal batch equilibrium experiments were carried out at T = 300.15 ± 1 K. The extraction was interpreted in terms of the distribution coefficient (KD). Maximum extraction efficiency (E = 95.5%) was obtained at 20% (v/v) TOA in butyl acetate with complexation constant KE2 = 1039.7 (kg mol–1)2 for the (2:1) complex. In addition to having a higher loading ratio (Z > 0.5), the overloading of amine(TOA) in the case of the citric acid + TOA + decanol system was also confirmed by spectroscopic (FTIR) analysis. The linear solvation energy relationship model was successfully applied to predict the distribution coefficient. The complex stoichiometry was also optimized using differential evolution. A close resemblance was observed between experimental and model values.