Separation of Pimelic Acid Using Tri-n-octylamine in Various Organic Solvents by Reactive Extraction: Equilibrium and Modeling

Separation of carboxylic acids from dilute aqueous solutions is a challenging problem, and reactive extraction has been examined as an attractive alternative for this process. This study aims to investigate the reactive extraction of pimelic acid (PA) using tri-n-octylamine (TOA) in 1-hexanol, 1-octanol, xylene, and n-hexane. The highest extraction efficiency (E (%)) and distribution coefficient (K D) were obtained at pH 3, which is the unadjusted pH of the aqueous PA solution. Extractive efficiency varied inversely with temperature and initial PA concentration but increased with the increase in TOA amount. The highest E (%) and K D values (98.5% and 67.2, respectively) were obtained with 1-hexanol at initial TOA and PA concentrations of 0.2700 and 0.0375 mol/kg, respectively. The process was modeled using multilinear regression, and the model closely correlated with experimental results for all organic solvents tested.