Liquid-Liquid Equilibrium of Water+ 1-Butanol+ Amino Acid (Glycine or DL-Alanine or L-Leucine)

Abstract

Amino acids play an important role both in animal metabolism and in industrial processes. Since they are rarely found in nature in a free form, they must be obtained from hydrolysis of protein-containing materials, or by fermentation. These production methods often result in aqueous mixtures containing various solutes including several types of amino acids. As a consequence, the cost of the separation processes and concentration of biomolecules from the media can be as high as 90 per cent of their total manufacturing cost. In this way, the design of such processes requires the knowledge of the partitioning behaviour in two-phase systems and thermodynamic models should support this optimization procedure. However, both the complexity of biomolecules, due to their multiple functional groups, and the crucial role of water, make the standard available thermodynamic models unattractive for the computation of phase behaviour. Therefore, new thermodynamic models for the description of the phase behaviour of systems containing biomolecules are required. In this work, liquid-liquid equilibria (LLE) of the ternary systems 1-butanol/water/amino acid (glycine, DL-alanine or L-leucine) were measured at 40 o C. The experimental results were correlated and interaction parameters for the modified-NRTL, UNIFAC and UNIFACCampinas models were estimated.