Process-Oriented Evaluation and Thermodynamic Modeling of Adsorption-Based Regeneration of Contaminated MDEA Solvents in Gas Sweetening Units

The accumulation of heat-stable salts (HSS), total organic acid (TOA) anions, and corrosion-derived metal ions in methyldiethanolamine (MDEA) solvents significantly reduces the efficiency of natural gas sweetening processes. Conventional reclamation techniques such as activated carbon adsorption and ion exchange suffer from limited selectivity and operational drawbacks under industrial conditions. This study presents a process-oriented evaluation and thermodynamic modeling of interpenetrating polymer network (IPN) nanocomposite hydrogels as advanced adsorbents for lean MDEA purification. Alginate–polyacrylamide-based hydrogels reinforced with inorganic and carbonaceous nanofillers were analyzed from a chemical engineering perspective focusing on adsorption equilibrium, thermodynamic feasibility, and process applicability. Adsorption performance toward TOA anions and heavy metals (Fe and Cr) was evaluated at multiple operating temperatures representative of industrial regeneration conditions. The adsorption behavior followed the Langmuir isotherm model, indicating monolayer adsorption dominance with increasing adsorption capacity at elevated temperatures. Thermodynamic analysis confirmed spontaneous and endothermic adsorption processes, suggesting improved regeneration efficiency under realistic plant conditions. The incorporation of nanofillers enhanced adsorption kinetics and improved structural stability by reducing excessive swelling while maintaining accessible active sites. Comparative assessment demonstrated superior impurity removal performance relative to conventional adsorbents currently used in gas processing units. The results provide a bridge between laboratory-scale material development and industrial solvent management strategies. The proposed adsorption framework enables integration of nanocomposite hydrogels into continuous MDEA reclamation systems, offering potential reductions in corrosion, foaming, and solvent degradation. This work contributes to sustainable gas processing by introducing a scalable adsorption-based regeneration concept supported by thermodynamic and process modeling analysis.