Browsing by Author "Quaye, Eric Nii Annang"

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    Carbon dioxide and ethane solubility in bis tri (fluromethylsulfonyl) imide-based ionic liquids: Selectivity measurements and modelling
    (Faculty of Graduate Studies and Research, University of Regina, 2024-05) Quaye, Eric Nii Annang; Henni, Amr; Ibrahim, Hussameldin; Kabir, Golam
    The urgent need to address carbon dioxide (CO2) emissions, a critical factor in escalating greenhouse gas levels and global warming, underscores the significance of effective capture and reduction methods. This research investigates the absorption of Carbon Dioxide and Ethane in three ionic liquids: 1-Decyl-3-MethylimidazoliumBis (Trifluromethylsulfonyl Imide) [IL1], 1-Hexadecyl-3-Methyl imidazoliumBis (Trifluromethylsulfonyl Imide) [IL2] and Triethytetradecyl Ammonium Bis (Trifluromethylsulfonyl Imide) [IL3]. Solubility measurements of CO2 were conducted from 303.15K to 343.15K and pressures up to 1.5 MPa, utilizing a gravimetric microbalance. The acquired solubility values were correlated with the Peng Robinson (PR) equation of state (EoS) using three mixing rules: Single - van Der Waals one (VDW1), Binary - van Der Waals two (VDW2), and the Wong-Sandler combined with the non-random two-liquid model (WS-NRTL). From the experimental findings, the ILs studied in this research showed the lowest Henry's Law constant (H) i.e. higher solubility of CO2 when compared to all Ionic Liquids in the Literature and even Selexol/ Genesorb 1753, a benchmark physical solvent in Industry. It only appeared less effective than 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide, a solvent with high molecular weight and viscosity, making them promising solvents for CO2 removal. [IL2] exhibited the lowest Henry's Law constant (H) i.e. the highest solubility among the studied ionic liquids (ILs) for CO2 absorption, The observed experimental trend wherein [IL1] and [IL3] capture relatively less CO2 than [IL2] up to 1.5 MPa at 30 ℃, 50 ℃, 60 ℃ and 70 ℃, and can be attributed to various factors inherent to the intermolecular structures and properties of these ionic liquids (ILs). Typically, the longer alkyl chains are associated with increased van der Waals interactions and higher solubility for gases like CO2. Thus, the longer alkyl chain in [IL2, 1-Hexa decyl-3-Methyl imidazolium Bis (Trifluromethyl-sulfonyl Imide)] facilitates a more effective CO2 absorption. Additionally, the larger molecular volume and increased surface area of the Hexadecyl-based IL provide more interaction sites for CO2 molecules. Furthermore, Henry’s law constant for Ethane in [IL1] was the highest (lowest solubility) relative to the two other ILs studied. The selectivity of CO2 over C2H6 was obtained and the overall selectivity was in the following order: [IL1] > [IL3]> [IL2]. Comparing this selectivity data to published ILs revealed they are only attractive when used for CO2 capture with no ethane present as in the case of flue gases. Furthermore, insights into the enthalpy and entropy of absorption underscored CO2 stronger interactions and higher solubility than Ethane. These results highlight the significant impact of IL structure on CO2 solubility, confirming the potential of tailored ILs for enhanced carbon capture strategies. In summary, the best ionic liquid amongst the three studied for CO2 capture is therefore [IL2] due to its lowest Henry’s law constant towards CO2 absorption, however [IL1] would be the best ionic liquid provided C2H6 co-absorption is of crucial importance and needs not to be avoided.