Ultrasonic velocity models in liquids (micro- and nanofluids): theoretical validations

Thermally induced characterization and modeling of physicochemical, acoustic, rheological, and thermodynamic properties of novel blends of (HEF + AEP) and (HEF + AMP) for CO2/H2S absorption

CO₂ and H₂S removal from flue gases is indispensable to be done for protection of environment with respect to global warming as well as clean air. Chemical absorption is one of the most developed and capable techniques for the removal of these sour gases. Among the many solvents, ionic liquids (ILs) are more capable due to their desirable green solvent properties. However, ILs being usually costlier, the blends of ILs and amines are more suggestive for absorption. In the present work, various essential characterization properties such as density, viscosity, sound velocity, and refractive index of two ionic liquid-amine blend systems viz. (1) 2-Hydroxy ethyl ammonium formate (HEF) + 1-(2-aminoethyl) piperazine (AEP) and (2) 2-Hydroxy ethyl ammonium formate (HEF) + 2-Amino-2-methyl-1-propanol (AMP) are reported. The temperature range for which all the measurements were conducted is 298.15 to 333.15 K. For both systems of (HEF + AEP) and (HEF + AMP), HEF mass fractions were varied from 0.2 to 0.8.The density and viscosity results were correlated as a function of temperature and concentration of ionic liquid and amine with Redlich-Kister and Grunberg-Nissan models, respectively. Moreover, feed forward neural network model (ANN) is explored for correlating experimentally determined sound velocity and refractive index data. The measured properties are further analyzed to estimate various thermodynamic as well as transport properties such as diffusivity of CO₂/H₂S in the (HEF + AEP) and (HEF + AMP), thermal expansion coefficients, and isentropic compressibility, ΔG⁰, ΔS⁰, ΔH⁰, using the available models in the literature.