Experimental study on CO₂ absorption in aqueous solutions and water–oil emulsions of TEA and blended MEA/DEA–TEA

The CO₂ absorptions in aqueous solutions and water-in-oil (W/O) emulsions of TEA, MEA–TEA, and DEA–TEA were investigated. By applying an experimental setup, the effects of reactant concentration (0.25–1 M for TEA, 0.1–0.3 M for MEA/DEA), temperature (15–35°C), volume fraction of the dispersed phase (0.4–0.6), and pressure (100–400 kPa) on capacity and rate of CO₂ absorption were measured and compared. The CO₂ absorption capacity in a TEA solution with a low/medium concentration (0.25–0.5 M) is more than the theoretical value while these values are approached to each other in the high concentration (1 M). The CO₂ absorption capacity of blended solutions (MEA/DEA–TEA) is higher than that of the TEA solution. By increasing the temperature, the CO₂ absorption capacities of the TEA and blended solutions are decreased by increasing the temperature. For the emulsion solutions, increasing the volume fraction of the dispersed phase causes a decrement in the capacity of absorption. In the low concentration of MEA/DEA (0.1 M), the aqueous solution has a higher absorption capacity than that of the emulsion while this trend is reverse in the high concentration of MEA/DEA (0.2–0.3 M). The CO₂ absorption rates of emulsions are higher than the rates of their corresponding aqueous solutions. For the TEA solutions, the rate of CO₂ absorption is controlled by the reaction rate while the shuttle mechanism enhances the absorption rate for the blended solutions. The CO₂ absorption capacity and rate for the TEA and blended solutions are increased by pressure while this increment is more significant for the emulsions.