Analysis of CO₂ equilibrium solubility of seven tertiary amine solvents using thermodynamic and ANN models

This work investigates the carbon dioxide (CO₂) equilibrium solubility of seven novel tertiary amines, which include 1-(2-Hydroxyethyl)pyrrolidine (1-(2-HE)PRLD), 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB), 3-diethylamino-1,2-propanediol (DE-1,2-PD), 4-(dipropylamino)-2-butanol (DPAB), 1-(2-Hydroxyethyl)-piperidine (1-(2-HE)PP), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-(dimethylamino)-2-butanol (DMAB). This analysis study was conducted at the amine concentration of 2.0 mol/L, over the temperature range of 298–333 K, and over the CO₂ partial pressure range of 3–101 kPa. Two approaches were adopted in this study. Some thermodynamic models were employed to correlate and predict the experimental results of CO₂ equilibrium solubility in the seven novel tertiary amines solution. The new Helei-Liu model and Liu et al. model for K₂ correlation were also developed. A comparison of the performances of these models in predicting CO₂ solubility showed that the Liu et al. model, which included the significant parameters of temperature, concentration of amine solution, physical solubility of CO₂, and total pressure, gave the best performance in predicting CO₂ equilibrium solubility in the newly formulated amine solutions. In addition, the artificial neutral network (ANN) approach was adopted for predicting the CO₂ equilibrium solubility of the seven tertiary amines. The predicted values of CO₂ solubility extracted from the ANN models were compared with those from the thermodynamic models in terms of the absolute average deviation (AAD).