3-Dimethylaminopropylamine (DMAPA) mixed with glycine (GLY) as an absorbent for carbon dioxide capture and subsequent utilization

3-dimethylaminopropylamine (DMAPA) and glycine (GLY) mixture was studied as a potential absorbent for carbon dioxide (CO2) capture and utilization. The solubility of CO2 in aqueous GLY-DMAPA solutions within the range of 0.1-2.0 mol/L (M) were measured experimentally using pressure differential technique. Utilization of CO2 was also studied by mixing the CO2-saturated absorbent with ethanol. The final products obtained were characterized by using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The solubility study revealed that the CO2 loading capacity increased as pressure of CO2 increased. In contrast, the loading capacity decreased when concentration of the absorbent and temperature in equilibrium cell increased. However, the total moles of CO2 absorbed showed an opposite trend such that net CO2 absorbed increased as concentration of absorbent increased. The chemical interactions between CO2 and GLY-DMAPA molecules were studied by analyzing the changes of characteristic peaks observed form the FTIR spectra. For CO2 utilization, the addition of ethanol as a reagent into 0.1 M CO2-saturated GLY-DMAPA solution did not produced any precipitate. Nonetheless, as the concentration of GLY-DMAPA increased from 0.5 M to 2.0 M, white precipitates were produced, indicated that the conversion of CO2 into solid compounds occurred instantaneously after the CO2 capture. The optimum concentration of GLY-DMAPA for CO2 capture and utilization depends on the amount of solids generated and the CO2 loading capacity of the absorbent. At 5 bar, the optimum concentration was found to be 1.0 M with 45 mg/g of solids recovered and CO2 loading capacity of 1.6 mol CO2/mol absorbent. The final product was identified as carbamate salt based on the main characteristic peaks present on the FTIR and XPS spectra.