Removal of acetic acid from aqueous solutions containing succinic acid and acetic acid by amine extractants

Extraction of succinic acid and acetic acid by tertiary and quaternary amine was investigated under various pHs. For both amines and for all amine concentrations, the distribution coefficients for both acids decreased with increasing values of pH. The extractability of tertiary amine (tri-n-octylamine) for both acids was higher than that of quaternary amine (Aliquat 336) at all pHs. The sharp decrease in distribution coefficients with increasing pH was begun at pKA of succinic acid and acetic acid, respectively. Based on the different extractability for succinic acid and acetic acid with pH, the selective removal of acetic acid from succinic and acetic acid aqueous mixture was carried out. In the case of extraction by 0.25 mol/kg trioctylamine dissolved in 1-octanol at pH 5.1, most of acetic acid from aqueous acid mixture could be removed.