Kinetic and equilibrium study of the chromatographic separation of glycine and ammonium

Abstract

Abstract Background Glycine is extensively applied in the field of food, medicine, agrochemistry, etc. It is usually commercially produced by the chemosynthesis method, which generates large amounts of by-product ammonium chloride. Methods In this paper, the separation of glycine and ammonium chloride was performed with chromatographic column, and deionized water as eluent. The adsorption equilibrium constant K of glycine and ammonium chloride was evaluated by frontal analysis. Based on the equilibrium-dispersive model and a linear driving force of chromatography, the overall mass transfer coefficient k m , axial dispersion coefficient D L , and bed voidage ε t of the column were obtained by moment analysis. Results At 50°C, the equilibrium constants measured were found to be 0.72 and 0.19 for glycine and ammonium chloride, respectively. At 60°C, the equilibrium constants increased to 0.80 and 0.21 for glycine and ammonium chloride, respectively. The value of axial dispersion coefficient D L of glycine had the same order of magnitude with ammonium chloride and was about two times larger than that of ammonium chloride. Their k m at 50°C and 60°C were 1.30 and 0.77 and 2.41 and 0.84 min−1 for glycine and ammonium chloride, respectively. Conclusions The obtained parameters used to simulate the elution curve and the simulation and experimental results matched well, which showed that the parameters obtained were effective. The results make foundation for further study on large-scale separation of glycine from ammonium chloride by SMB chromatography.