A study on the solubilities of amino acids in water at various pH values

• Main Author: 陳志翰
• Other Authors: 曾憲政
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/14735265791249518329

碩士 === 國立臺灣科技大學 === 化學工程系 === 92 === The objective of this study is to investigate the solubility behavior of amino acid in water at various pH values . In the experimental part, a spectrophotometer was employed to analyze the solubility data for four amino acids of DL-alanine, L-leucine, L-isoleucine and L-serine in water. It was observed that the pH effect, changing from 2 to 10 adjusted by HCl or NaOH, is very significant to the solubility data. This is due to the fact that amino acids appear in several forms, which are neutral zwitterions, amino acid cationic and anionic species, during the dissolution process. These species are not only equilibrated with each other but also with hydrogen ions. In the theoretical part, physical and chemical equilibria were considered simultaneously to model the solubility of amino acids in water. A calculation scheme combined of chemical model, activity coefficient model and equilibrium criterion was achieved. The Wilson[21]、TK-Wilson[23] or modified UNIFAC[26] model was used to describe the nonideal behavior in the solution. The calculated results agree well with the experimental data.