Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium
Carbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO<sub>2</sub> emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the pot...
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| author | Raheem Akinosho Amr Henni Farhan Shaikh |
| author_facet | Raheem Akinosho Amr Henni Farhan Shaikh |
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| description | Carbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO<sub>2</sub> emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the potential of particular ionic liquids (ILs) in capturing CO<sub>2</sub> for the sweetening of natural and other gases. The solubility of CO<sub>2</sub> was measured in three distinct ILs, which shared a common anion (triflate, TfO) but differed in their cations. The selected ionic liquids were {1-butyl-3-methylimidazolium triflate [BMIM][TfO], 1-butyl-1-methylpyrrolidinium triflate [BMP][TfO], and 1-butyl-4-methylpyridium triflate [MBPY][TfO]}. The solvents were screened based on results from a molecular computational study that predicted low CO<sub>2</sub> Henry’s Law constants. Solubility measurements were conducted at 303.15 K, 323.15 K, and 343.15 K and pressures up to 1.5 MPa using a gravimetric microbalance (IGA-003). The CO<sub>2</sub> experimental results were modeled using the Peng–Robinson Equation of state with three mixing rules: van der Waals one (vdWI), van der Waals two (vdWII), and the non-random two-liquid (NRTL) Wong–Sandler (WS) mixing rule. For the three ILs, the NRTL-WS mixing rule regressed the data with the lowest average deviation percentage of 1.24%. The three solvents had similar alkyl chains but slightly different polarities. [MBPY][TfO], with the largest size, exhibited the highest CO<sub>2</sub> solubility at all three temperatures. Calculation of its relative polarity descriptor (N) shows it was the least polar of the three ILs. Conversely, [BMP][TfO] showed the highest Henry’s Law constant (lowest solubility) across the studied temperature range. Comparing the results to published data, the study concludes that triflate-based ionic liquids with three fluorine atoms had lower capacity for CO<sub>2</sub> compared to bis(trifluoromethylsulfonyl) imide (Tf2N)-based ionic liquids with six fluorine atoms. Additionally, the study provided data on the enthalpy and entropy of absorption. A final comparison shows that the ILs had a lower CO<sub>2</sub> capacity than Selexol, a solvent widely used in commercial carbon capture operations. Compared to other ILs, the results confirm that the type of anion had a more significant impact on solubility than the cation. |
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| spelling | doaj-art-ee98e2f956bd4f8fb6dae3d243227c1e2025-08-20T03:27:29ZengMDPI AGLiquids2673-80152025-05-01521510.3390/liquids5020015Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and PyrrolidiniumRaheem Akinosho0Amr Henni1Farhan Shaikh2Clean Energy Technologies Research Institute (CETRi), University of Regina, Regina, SK S4S0A2, CanadaClean Energy Technologies Research Institute (CETRi), University of Regina, Regina, SK S4S0A2, CanadaClean Energy Technologies Research Institute (CETRi), University of Regina, Regina, SK S4S0A2, CanadaCarbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO<sub>2</sub> emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the potential of particular ionic liquids (ILs) in capturing CO<sub>2</sub> for the sweetening of natural and other gases. The solubility of CO<sub>2</sub> was measured in three distinct ILs, which shared a common anion (triflate, TfO) but differed in their cations. The selected ionic liquids were {1-butyl-3-methylimidazolium triflate [BMIM][TfO], 1-butyl-1-methylpyrrolidinium triflate [BMP][TfO], and 1-butyl-4-methylpyridium triflate [MBPY][TfO]}. The solvents were screened based on results from a molecular computational study that predicted low CO<sub>2</sub> Henry’s Law constants. Solubility measurements were conducted at 303.15 K, 323.15 K, and 343.15 K and pressures up to 1.5 MPa using a gravimetric microbalance (IGA-003). The CO<sub>2</sub> experimental results were modeled using the Peng–Robinson Equation of state with three mixing rules: van der Waals one (vdWI), van der Waals two (vdWII), and the non-random two-liquid (NRTL) Wong–Sandler (WS) mixing rule. For the three ILs, the NRTL-WS mixing rule regressed the data with the lowest average deviation percentage of 1.24%. The three solvents had similar alkyl chains but slightly different polarities. [MBPY][TfO], with the largest size, exhibited the highest CO<sub>2</sub> solubility at all three temperatures. Calculation of its relative polarity descriptor (N) shows it was the least polar of the three ILs. Conversely, [BMP][TfO] showed the highest Henry’s Law constant (lowest solubility) across the studied temperature range. Comparing the results to published data, the study concludes that triflate-based ionic liquids with three fluorine atoms had lower capacity for CO<sub>2</sub> compared to bis(trifluoromethylsulfonyl) imide (Tf2N)-based ionic liquids with six fluorine atoms. Additionally, the study provided data on the enthalpy and entropy of absorption. A final comparison shows that the ILs had a lower CO<sub>2</sub> capacity than Selexol, a solvent widely used in commercial carbon capture operations. Compared to other ILs, the results confirm that the type of anion had a more significant impact on solubility than the cation.https://www.mdpi.com/2673-8015/5/2/15carbon dioxideionic liquidstriflatePeng–Robinson EoS |
| spellingShingle | Raheem Akinosho Amr Henni Farhan Shaikh Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium Liquids carbon dioxide ionic liquids triflate Peng–Robinson EoS |
| title | Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium |
| title_full | Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium |
| title_fullStr | Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium |
| title_full_unstemmed | Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium |
| title_short | Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium |
| title_sort | measurement and modelling of carbon dioxide in triflate based ionic liquids imidazolium pyridinium and pyrrolidinium |
| topic | carbon dioxide ionic liquids triflate Peng–Robinson EoS |
| url | https://www.mdpi.com/2673-8015/5/2/15 |
| work_keys_str_mv | AT raheemakinosho measurementandmodellingofcarbondioxideintriflatebasedionicliquidsimidazoliumpyridiniumandpyrrolidinium AT amrhenni measurementandmodellingofcarbondioxideintriflatebasedionicliquidsimidazoliumpyridiniumandpyrrolidinium AT farhanshaikh measurementandmodellingofcarbondioxideintriflatebasedionicliquidsimidazoliumpyridiniumandpyrrolidinium |