Surface Tension and Derived Surface Thermodynamic Properties of Aqueous Sodium Salt of L-Phenylalanine

Objectives: To investigate experimental data of surface tension of aqueous sodium salt of L-phenylalanine (Na-Phe) at temperatures ranging from 298.15 to 343.15 K and concentration ranging from 0.05 to 0.40 (w). Methodology: This work was carried out through an optical contact angle tensiometer (OCA 15 EC). It is a video based instrument which employs a pendant drop method for contact angle measurement. Findings: It was observed that surface tension values rise as aqueous Na-Phe concentration increases and decrease with the increase in system’s temperature. Experimental surface tension data were used to calculate the dervied surface thermodynamic properties such as surface enthalpy and entropy. Surface enthalpy was found to increase with concentration and tend to decrease with the rise in temperature. While, estimated surface entropy values were found to decrease with the increase in Na-Phe concentration. Temperature and concentration dependent empirical correlation was utilized to predict the surface tension data. A good agreement was found between the experimental and correlated data. Applications/Improvements: The findings reported in this study could be helpful significantly for the selection of appropriate solvent, and in the calculations for the efficient design of absorption column.