Improving the performance of membrane contactors for carbon dioxide stripping from water: Experimental and theoretical analysis

Carbon capture and storage (CCS) and industrial processes are driving the demand for CO₂ stripping from water. Membrane contactors are considered a favorable solution to the conventional challenges of CO₂ stripping from water, such as inefficiency and high space occupancy. However, the factors affecting membrane contactor performance have not been systemically investigated in the context of efficient CO₂ stripping. This study analyzed the factors affecting the membrane contactors for the CO₂ stripping process based on experiments and theoretical modeling. The factors are classified according to advection (e.g., liquid flow rate), diffusion (e.g., vacuum pressure and pH), and membrane (e.g., long-term operation and arrangement). A high liquid flow rate increased the CO₂ stripping flux, whereas it decreased the CO₂ removal efficiency. At vacuum pressure, CO₂ stripping depended on the vacuum pressure but it was not effective in the air-combination mode. It is also important to maintain pH 5 as pH significantly affects the diffusion. In the long-term experiment, membrane fouling and pore swelling were not observed to cause performance degradation. Further, parallel and series designs for membrane contactors were compared, the parallel design exhibits superior CO₂ stripping performance. This study provides strategies for using membrane contactors for efficient CO₂ stripping.