CO2 Absorption by Ethanolamine-Based Ternary Deep Eutectic Solvents
Ternary deep eutectic solvents(DES)comprising choline chloride(ChCl),glycerol(Gly)and ethanolamine(MEA)with different molar ratios were prepared.The CO2 absorption ability of the ternary DES was investigated at room temperature and under atmospheric pressure.Among four ternary DES samples prepared with different molar ratios,a ChCl-Gly-MEA(1∶1∶10)ternary DES was found to absorb the most CO2 at a capacity of 0.18 g CO2(DES per gram)at 298 K and 101.3 kPa.The experimental results showed that the CO2 absorption capacity of ChCl-Gly-MEA(1∶1∶10)ternary DES increased with an increase in gas flow rate and a decrease in water content.The gas flow rate improved the mass transfer efficiency of CO2 in the ternary DES system,and shortened the time required for CO2 absorption to reach equilibrium.However,the addition of water could weaken the hydrogen bonding interaction among the three components in the DES system.Results from Fourier transform infrared(FT-IR)and nuclear magnetic resonance(NMR)spectroscopy indicated that CO2 interacted with the amino groups in DES to form carbamates.The absorption of CO2 by ChCl-Gly-MEA underwent both physical and chemical absorption,and the chemical absorption was significantly enhanced by the addition of MEA.A recovery experiment showed that no obvious loss in CO2 absorption was detected after five absorption/desorption cycles with an absorption rate of 97.3％being retained.
deep eutectic solvent(DES)carbon dioxidephysical absorptionchemical absorptionreproducibility
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