Investigation of carbon dioxide absorption performance in amine amino acid salts for upgrading biogas applications: Blended absorbents of piperazine and amino acid solutions

•Amine amino acid solution (AAAS) explored as an alternative benchmark MEA-based solvents.•PZ: Lys absorbent has high CO2 cyclic capacity and lower regeneration heat.•Explored the CO2 absorption mechanism in PZ: Lys and PZ: Ala using 13C NMR.•Measured density, dynamic viscosity, and vapor pressure of PZ: Lys solution at t = 303.15 K to 353.15 K. The increasing amount of CO2 in the atmosphere is a critical environmental issue, necessitating the development of efficient CO2 capture technologies. Amine amino acid solutions (AAAS) have demonstrated potential in improving CO2 absorption and desorption. This study explores the efficiency of various AAAS, including piperazine (PZ), glycine (Gly), lysine (Lys), sarcosine (Sar), and alanine (Ala), under specific experimental conditions. The CO2 absorption and desorption processes were investigated using AAAS under conditions of 45 % CO2 at 313.15 K and with pure N2 at 353.15 K, respectively. The findings obtained for CO2 loading, regeneration rate, CO2 desorption heat, and 13C nuclear magnetic resonance (NMR) are valuable for understanding their impacts on the design and improvement of energy efficiency CO2 capture techniques. Furthermore, the physicochemical properties of PZ + lysine solutions such as density, viscosity, and vapor pressure were also measured at equimolar concentration ranges such as 0.75 M, 1.0 M, 1.25 M, and 1.5 M at T = 303.15 K to 353.15 K and 0.1 MPa pressure. The study revealed significant enhancements in CO2 absorption and desorption with the addition of AAAS compared to monoethanolamine (MEA) solutions. Notably, among all the solutions, the PZ + lysine solution exhibited the maximum CO2 cyclic capacity at 0.792 mol CO2/mol absorbent, and the lowest regeneration heat. These findings provide valuable insights into the design and improvement of energy-efficient CO2 capture techniques. [Display omitted]