Viscosity prediction of the carbon dioxide loaded aqueous solutions of alkanolamines: Thermodynamic approach

The Eyring absolute rate theory (EART) based methodology has been used for estimation of the dynamic viscosity of CO2 loaded aqueous solutions of a representative amine-monoethanolamine (MEA). The electrolyte-NRTL model is applied to estimate the activation free energy of the solution and consequently enable prediction of the dynamic viscosity of the electrolyte CO2:MEA:H2O system. According to EART for the dynamic viscosity of asolution, (Equation presented). η, η,₀, V, V₀, R and Δ F^≠are the dynamic viscosity of solution and pure solvent, the solution and pure solvent molar volume, gas constant and activation free energy for the flow process, respectively. The Δ F^≠was generally related to the Gibbs free energy of mixing, f(Δ G_mix ^≠). (Equation presented) (Figure presented) Solution pH and Ionic Strength, MEA 30% (Figure presented) Effects of viscosity on the liquid side mass transfer coefficient (Figure presented) In equation (2), ΔG_{id, mix} ^≠, can be calculated through the system speciation which is available from thermodynamic modeling. (e.g. Aspen Plus®). ΔG_ex ^≠, is related to the solution components (species) mole fractions and their corresponding activity coefficients. For a multicomponent mixture, Eq (1) can be written as, (Equation presented) X_i, V_i,0 and η_i are the mole fraction of component i, molar volume and viscosity of the pure chemical i, respectively.