Advancing Carbon Neutrality through a Novel Aqueous Tetraethylenepentamine (TEPA) and 2-Dimethylaminoethanol (DMAE) Amine Blend for Postcombustion CO ₂ Capture

In this investigation, a novel aqueous amine blend comprising Tetraethylenepentamine (TEPA) and 2-Dimethylaminoethanol (DMAE) was formulated and systematically evaluated for postcombustion CO2 capture. The purpose of the study is to provide a potential solvent that would assist in achieving India’s vision of carbon neutrality and net-zero emissions by 2070. Response surface methodology (RSM) with a central composite design (CCD) was employed to optimize the operating parameters within the ranges: temperature (T) = 298.15–333.15 K, CO2 partial pressure (PCO2) = 10.13–25.33 kPa, mole fraction of TEPA (mTEPA) = 0.05–0.20, and solution concentration (C) = 1–3 mol/L. A quadratic model was developed, and analysis of variance (ANOVA) confirmed its significance with R2 = 0.9955 and predicted R2 = 0.9841, indicating excellent agreement between experimental and predicted values. The maximum equilibrium CO2 loading (α = 0.9978 mol of CO2/mol of amine) was observed at T = 306.90 K, PCO2 = 21.53 kPa, mTEPA = 0.16, and C = 1.50 mol/L. RSM prediction for optimization: α value = 0.997879 mol of CO2/mol of amine at T = 307.12 K, PCO2 = 21.53 kPa, mTEPA = 0.16, and C = 1.5 mol/L. RSM predictions were validated experimentally, showing deviations below 1%. The reaction mechanism and its authentication by speciation analysis were done by an 13C NMR investigation. Gibbs–Helmholtz approach yielded a heat of absorption of −54.15 kJ/mol, suggesting moderate energy requirement. Toxicity assessment revealed that the novel TEPA + DMAE amine blend has a slightly toxic nature (lethal dose value, LD50 = 2420 mg/kg).