Novel aqueous amine blend of 2-(Butylamino)ethanol and 2-Dimethylaminoethanol for CO2 capture: Equilibrium CO2 loading, RSM optimization, desorption study, characterization and toxicity assessment

Abstract

This research is necessary to provide a potential aqueous amine blend solvent for industrial application to help in overcoming the challenges of drastic climate change. The performance of a novel aqueous amine blend of 2-(butylamino)ethanol (BAE) and 2-Dimethylaminoethanol (DMAE) in terms of CO2 absorption and desorption was investigated. This study focused on aspects such as equilibrium CO2 loading, absorption capacity, empirical modeling, cyclic equilibrium CO2 loading, cyclic capacity, heat duty, regeneration efficiency, pH effect, heat of absorption, toxicity assessment, 13C NMR and FTIR speciation, response surface methodology (RSM) modeling, and optimization. The entire CO2 absorption experiment was performed in the temperature (T) ranging from 298.15 to 333.15 K, CO2 partial pressure (PCO2) ranged from 10.13 to 25.33 kPa, mole fraction of BAE (mBAE) changed from 0.05 to 0.20, and solution concentration (C) varied from 1 to 3 mol/L. Desorption experiments were carried out at a constant temperature of 393.15 K and a constant pressure of 25.33 kPa. At T = 313.15 K, PCO2 = 25.33 kPa, mBAE = 0.20, and C = 1 mol/L, CO2 absorption experiments yielded a maximum equilibrium CO2 loading of 0.9365 mol CO2/mol amine. At C = 3 mol/L, this novel blend exhibited 71.23 % higher cyclic capacity than conventional 30 wt% monoethanolamine (MEA). Heat duty and regeneration efficiency of 3 mol/L solution were found to be 112.96 kJ/mol CO2 and 83.27 %, respectively. This amine blend's heat of CO2 absorption was determined to be −72.74 kJ/mol. RSM predicted optimum equilibrium CO2 loading of 0.829265 mol CO2/mol amine at T = 306.90 K, PCO2 = 21.22 kPa, mBAE = 0.16, and C = 1.5 mol/L.