Extraction Equilibria of Amino Acids and Dipeptides in Various Organic Solutions

Abstract

Experimental data on the partitioning of amino acids (tryptophan, phenylalanine) and dipeptides (tryptophan-leucine, phenylalanine-leucine) between the aqueous feed phase and the organic solvent phase are presented. The organic solvent phase consists ofa carrier, sodium di-2-ethylhexyl sulfosuccinate/ quaternary ammonium salt/dioleyl phosphoric acid, dissolved in (Z)-9-octadecen-1-ol (an organic solvent). The equilibrium distribution coefficient for extractions is determined by varying the following experimental conditions: feed solution pH, initial feed phase concentration, and composition of organic phase. The partition coefficient for the stripping process is also determined by varying the stripping agent (sodium hydroxide, sodium chloride, sodium carbonate), the concentration, and the pH of the stripping solution. The extraction and stripping reaction coefficients are calculated by combining the experimental data and the kinetic expressions for interfacial reactions. The variation of the values of the coefficients with the solute type (i.e. amino acid or dipeptide) and with the operating conditions of the system di-2-ethylhexyl sulfosuccinate in (Z)-9-octadecen-1-ol is presented.