Liquid-liquid extraction of lactic acid with alamine 336

The extraction of lactic acid (HL) from aqueous solutions by Alamine 336 (B) dissolved in toluene was studied. Experiments were performed in the temperature range of 25-60 degrees C and for two amine concentrations of 20 and 40% (v/v) in toluene. The extent to which the organic phase (amine + toluene) may be loaded with lactic acid is expressed as a loading ratio, Z = C(<(HL)over bar>)/C-B. Z values are independent of the amine concentration and, hence, the extracted complex contains only one molecule of amine. Z decreases with increasing temperature. Experimental results indicate that the system presents overloading, i.e. Z > 1. The extraction equilibrium may be interpreted as a result of consecutive formation of three acid-amine species with stoichiometries of 1:1, 2:1 and 3:1.