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.