Effect of physical properties of synthesized protic ionic liquid on carbon dioxide absorption rate

The concentration of carbon dioxide gas has accelerated over the last two decades which cause drastic changes in the climatic conditions. In industries, carbon capture plants use a volatile organic solvent which causes many environmental threats. So, a low-cost green absorbent has been formulated with nontoxicity and high selectivity properties for absorbing carbon dioxide gas. This paper contains the synthesis process along with the structure confirmation using ¹H NMR, ¹³C NMR, FT-IR, and mass spectroscopy. Density, viscosity, and diffusivity are measured at different ranges with standard instruments. The kinetic studies were also conducted in a standard predefined-interface stirred cell reactor. The kinetic parameters were calculated at different parameters like agitation speeds, absorption temperature, initial concentrations of ionic liquid, and partial pressure of carbon dioxide. The reaction regime of carbon dioxide absorption is found to be in fast reaction kinetics with pseudo-first-order. The reaction rate and the activation energy of CO₂ absorption are experimentally determined in the range of 299 to 333 K with different initial concentrations of ionic liquid (0.1-1.1 kmol/m³). The second-order rate constant and activation energy of carbon dioxide absorption in the synthesized ionic liquid is found to be 9.48 × 10³ m³ mol^-1 s^-1 and 16.61 kJ mol^-1 respectively. On increasing the viscosity of the reacting solvent, the diffusivity of CO₂ gas molecules decreases, and thus the rate of absorption decreases. This solvent has shown great potential to absorb CO₂ at a large scale.