A rotating packed bed (RPB) was employed as a highly effective reactor to intensify CO, capture in a green and natural amino acid salt absorbent, potassium sarcosine (KSAR), from the flue gas containing a low CO, concentration. Experimental results show that a good CO, capture performance, presented in terms of CO, capture efficiency and overall volumetric mass transfer coefficient (K(G)a), can be obtained at a low CO2 concentration of 2-6%. CO2 capture efficiency could reach higher than 80% at a relatively high gas-liquid ratio, with CO2 loading up to 0.17 mol of CO2/mol of KSAR. Comparison results with a packed column show that a RPB can obtain higher CO2 capture performance with a smaller device size. Moreover, a mathematical model was developed to describe the mass transfer process in a RPB. Calculated values of KGa agreed well with experimental data, with a deviation within +/- 25%, and the tendency of the CO2 concentration at the outlet of the RPB can be well-predicted under a high liquid flow rate and high rotation speed. The model provides a view on the mass transfer process of CO2 capture in the RPB and offers a theoretical basis for the design and application of a RPB in the future.