The complex compound of dithizone-Co(Ⅱ) was separated and concentrated from the aqueous phase to n-octanol by solvent sublation. From the analysis of the coalescence behavior of bubbles on water-organic interface, the conception of critical bubble radius was proposed, and the value of the critical bubble radius in the water-octanol system was obtained: 1.196 × 10-3 m. The simulation of the mathematical model using CBR and experimental data is completed with perfect results, and the simulation of the mathematical model using CBR is very different with the classic one. The analytical results proved that the critical bubble radius should be adequately considered in mathematical model of solvent sublation.