Temperature and Concentration Effects on Physical and Thermodynamic Properties of Unloaded and CO2‐Loaded Aqueous Solutions: Experiments and Empirical Modeling

Amines are widely used in carbon capture, and high temperatures during stripping operations alter the solvent's nature. The study explores the physical and thermodynamic property changes of aqueous monoethanolamine (MEA), piperazine (PZ), and potassium carbonate (K2CO3) solutions, as these properties influence the CO2 absorption kinetics and regeneration of solvent. The solutions were tested from 283 to 333 K at varying concentrations. CO2 dissolution in aqueous solutions was assessed at room temperature and 0.0344 bar pressure. The density (ρ), viscosity (μ), and surface tension (σ) decrease with temperature increase for unloaded and CO2‐loaded solutions; while these properties increase with concentration. The thermal expansion coefficient (βρ) increases with temperature. A data‐based model was developed to predict ρ, μ, and σ as a function of CO2 loading, temperature, average solvent molecular weight, and concentration. The data‐based models predicted the properties with over 95% accuracy. Volumetric properties, viscosity deviation, and excess Gibbs free energy of activation are calculated for MEA to study intermolecular interactions. The thermodynamic results of MEA indicate the solvent behaves more ideally as concentration and temperature increas.