Comprehensive analysis of thermodynamic models for CO₂ absorption into a blended N,N-diethylethanolamine-1,6-hexamethyl diamine (DEEA-HMDA) amine

In this work, CO₂ equilibrium solubility of 1M N,N-diethylethanolamine (DEEA):2M 1,6-hexamethyl diamine (HMDA), 1.5M DEEA:1.5M HMDA and 2M DEEA:1M HMDA was studied with a temperature range of 298–333 K and CO₂ partial pressure range of 8–100 kPa. Seven thermodynamic models including Empirical model, Kent and Eisenberg (KE) model, Hu–Chakma model, Austgen model, Helei Liu model, Liu et al. model, and Li–Shen model were developed by correlating reaction equilibrium constants with observed equilibrium solubility of CO₂ in mixed amine solvents. The evaluation of those models was conducted in terms of the average absolute relative deviation (AARD). The results indicated that Liu et al. model considering T, [Amine], P_total and [CO₂(aq)] can better represent this complex system with an AARD of 8.06%. Meanwhile, comprehensive comparison and analysis were also performed to identify the contribution of parameters to develop models, which could provide a guideline for the development of accurate thermodynamic models for representation of thermodynamic behaviors.