Lactic Acid Extraction in Systems Containing Organic Amines

A new high-performance system for lactic acid (HL) extraction from glucose-containing solutions is proposed. Trialkylbenzylammonium sulfate (C7–C9 fraction) with p-tert-butyl phenol in a diluent is used as the extractant. The maximum extraction region for HL is found to be at pH = 5.0–7.0, which coincides with the range of optimal pH values for glucose conversion to lactic acid. In five extraction stages, at an organic to aqueous phase ratio of 1:1, the acid recovery is 96.7%. HL stripping is carried out with 2.0–3.0 M NaOH solutions, which achieves a significant increase in HL concentration. The stripping process in alkaline medium is easy (not less than 93.45% in one stage) due to the formation of trialkylbenzylammonium phenolate in the organic phase. Regeneration and conversion of the extractant to the SO4-form (TABAS) are carried out by treating the organic phase with sulfuric acid.