Investigation of CO2 solubility in monoethanolamine hydrochloride based deep eutectic solvents and physical properties measurements

Deep eutectic solvents(DESs) have drawn a growing research interest for applications in a wide range of scientific and industrial arenas. However, a limited effort has been reported in the area of gas separation processes and particularly the carbon dioxide capture. This study introduces a novel set of DESs that were prepared by complexing ethylenediamine(EDA), monoethanolamine(MEA), tetraethylenepentamine(TEPA), triethylenetetramine(TETA) and diethylenetriamine(DETA) as hydrogen bond donors to monoethanolamide hydrochloride(EAHC) salt as a hydrogen bond acceptor. The absorption capacity of COwas evaluated by exploiting a method based on measuring the pressure drop during the absorption process. The solubility of different DESs was studied at a temperature of 313.15 K and initial pressure of 0.8 MPa. The DES systems 1 EAHC:9 DETA, 1 EAHC:9 TETA and 1 EAHC:9 TEPA achieved the highest COsolubility of 0.6611, 0.6572 and 0.7017 mol CO·(mole DES)respectively. The results showed that COsolubility in the DESs increased with increasing the molar ratio of hydrogen bond donor. In addition, the COsolubility increased as the number of amine groups in the solvent increases, therefore, increasing the alkyl chain length in the DESs, resulted in increasing the COsolubility. FTIR analysis confirms the DES synthesis since no new functional group was identified. The FTIR spectra also revealed the carbamate formation in DES-COmixtures. In addition, the densities and viscosities of the synthesized DESs were also measured.The COinitial investigation of reported DESs shows that these can be potential alternative for conventional solvents in COcapture processes.