Extraction equilibria of propionic acid from aqueous solutions by Amberlite LA-2 in diluent solvents

Amberlite LA-2 (a secondary amine) was studied for its ability to extract propionic acid at different amine concentrations. The extraction of propionic acid by Amberlite LA-2 dissolved in seven single solvents (cyclohexane, 2-octanone, toluene, methyl isobutyl ketone, isooctane, haxane and 1-octanol) was investigated under various amine concentrations at 298.15 K. Using Bizek's approach, two acids: amine complexes, (HO):(R2N) and (HO):(R2N)2, are assumed to exist in the organic phase in case of proton-donating diluents, while the complexes (HO):(R2N) and (HO)2:(R2N)3 are suggested in the case of non-proton-donating diluents. Important data for design of separation units have been obtained as a result of batch experiments. These data are distribution coefficients (D), loading factors (Z), extraction efficiency (E) and overall extraction constants (K11, K12, K23). The maximum removal of glycolic acid is 94.68% with MIBK and 0.93 mol L−1 initial concentration of Amberlite LA-2.