Study On The Surface Tension Of Amine Aqueous Solution For CO₂ Capture

In recent decades, atmospheric levels of CO₂ have increased rapidly due to the utilization of grand amount of fossil fuel. The reduction of CO₂ emission became a global issue. The surface tensions of the aqueous solutions of amines are required when designing or simulating an absorption column for CO₂ absorption associated with chemical reactions. However, few experiments concerning the surface tensions of the aqueous solutions of amines have been reported by far, and the temperature and concentration dependences of the thermodynamic properties like surface tensions, surface enthalpy and surface entropy have not been well documented.In this thesis, the surface tensions of the binary mixtures of DEA-water and ternary mixture of MDEA-DEA-water at different concentrations and temperatures were respectively measured by using an automatic surface tension-meter. The experimental data were correlated with an linear empirical model and the agreement was satisfactory. The surface enthalpy and surface entropy were determined. The temperature and concentration dependence of surface tensions, surface enthalpy and surface entropy were analyzed.Our results show that without absorbing CO₂, both the surface tension-concentration and surface tension-temperature relationships can be well described by linear functions. The surface tensions increase with the increase of amine concentration while decrease with increasing temperature. Moreover, both the surface enthalpy and surface entropy are dependent on the concentration of amines (w), and they tend to increase with increasing w when w is low, but decrease with the increase of w when w is high.