Surfactant addition to alkali solutions for increased carbon dioxide absorption rates

To meet the growing need for CO₂ capture and storage technology, Michigan Technological University is studying CO₂ capture using alkali-based solvents. The objective of the present study was to find a way to increase the absorption rate of CO₂ into an alkali solution without reducing the absorption capacity of the solution. One approach to increasing absorption rate is to use a surfactant to chemically alter the gas bubble size. The surfactant chosen for the study was a neutral-charge polypropylene glycol methyl ether (PPGME) with a molecular weight of 200. Experiments were conducted to study the absorption rate of CO₂ at varying surfactant concentrations. Results showed that as the concentration of PPGME increased in solution, the absorption rate also increased. The CO₂ absorption rate increased from 3.45 × 10^-3 mol/min CO₂ at 0g/L PPGME to 3.92 × 10^-3 mol/min CO₂ at 0.48 g/L PPGME. This amounted to a 14% increase in the CO₂ absorption rate with no decrease in the absorption capacity of the solution.