Résumé
The study on the performance of amino acid adsorption, activation and thermal condensation on inorganic oxides is helpful to make clear the essential function of silica, alumina and clay during the prebiotic chemical evolution, such as the formation of peptide bonds. In this work, the adsorption and thermal condensation performance of glycine on silica were investigated. Glycine was adsorbed on the surface of silica from aqueous solutions with various concentrations and pHs, and the samples were characterized by DTG, XRD, FT-IR and TPD-MS. It is shown by DTG results that the adsorption performance does not meet the Langmuir model. XRD and FT-IR results indicate that when the equilibrium concentration is below 0.073 mol/L, the adsorption may take place only on specific sites; and it is probably resulted from the interaction between the NH3+ moiety of glycine and the silanolate group ( Si-O-) of silica. At higher equilibrium concentrations (> 0.073 mol/L), the precipitation of beta-glycine on silica surface was