The Thermodynamic Properties And Intermolecular Interaction Research Of Amino Acid Aqueous Solution Based On Activity Model

Amino acids are the basic composition unit of protein and peptide, it is not only the raw materials of human hormones, enzymes and antibodies, but also the important material of biology, pharmaceutical, food, fine chemical industry and other industrial process. In the prosess of separation and purification of amino acids, the activity of amino acid in the amino acid aqueous solution and the microscopic interaction between molecular are also the main design basis for industrial production process. Through studying thermodynamic properties of amino acid aqueous solution, we obtained activity model of amino acid. This can help to understand the information of molecular interactions in the amino acid solution system. Specific research contents are as follows:(1) In this paper, choosing alanine and glycine, arginine, cysteine, glutamic acid, lysine, valine, leucine, serine and methionine as the main research objects, we analyzed and summarised the osmotic coefficient and activity coefficient of glycine at the temperature of288.15K,293.15K,298.15K,303.15K and alanine at the temperature of288.15K,293.15K,298.15K,303.15K,310.15K and the other amino acids in the298.15K; besides, we also analyzed and summarised the solubility data in the water of20kinds of amino acids in different temperature and pressure.It is convenient for researchers who needs this data.(2) Fitting the thermodynamic data to amino acids-water binary system by using Pitzer model, the fitting effect is good, then we got the parameter values of Pitzer model, namely the second willy coefficient BMXΦ(I)、BMXγ(l), and the third willy coefficient CMXΦ(I)、CMXγ(I).Therefore, we established the activity model of amino acids aqueous solution system on the basis of the Pitzer model with the quality of molar concentration as the unit; Fitting the thermodynamic data to amino acids water of binary system by using the regular solution model, then we got interaction energy parameters ω Therefore, we established the activity model of amino acids aqueous solution system on the basis of the regular solution model with the mole fraction of amino acids as the unit.(3) After obtainning the activity model of amino acids, then combining with the summarised solubility data, we could calculate the dissolving equilibrium constant of glycine at the temperature of288.15K,293.15K,293.15K,303.15K,310.15K and DL-alanine at the temperature of288.15K,293.15K,298.15K,303.15K, as well as arginine, glutamic acid, L-leucine, DL-serine, DL-valine, DL-methionine at the temperature of298.15K. Besides, we also got the dissolving enthalpy change of the DL-alanine and glycine.(4) We used the Pitzer model to analyze the interaction between the solute and solute of these amino acid solution, namely the interaction between amino acids amino acid. Besides, we obtained the critical concentration points of the glycine at the temperature of298.15K and293.15K (2.9mo/Kg and3.4mol/Kg), alanine at the temperature of288.15K and293.15K (1.5mol/Kg) and303.15K (0.3mol/Kg), glutamic acid at the temperature of298.15K (0.06mol/Kg); Analyzing the interaction between solute-solvent by using the regular solution model, we obtained the interaction between amino-water of glycine and alanine at different temperatures, as well as all the reseaching object amino acid at the temperature of298.15K.