Adsorption equilibrium and diffusion coefficient of baicalein and wogonin in supercritical CO2/methanol

Baicalein, which exhibits antioxidant activity and wogonin, with anticancer activity, can be extracted from Scutellaria baicalensis Georgi. Their similar structures pose a challenge to further isolation. Supercritical Fluid-Simulated Moving Bed (SF-SMB) can function as a large-scale green separation process based on the adsorptive difference between them. The adsorption data of baicalein and wogonin on ZorBax SB-CN column in supercritical carbon dioxide/methanol were determined using the Elution by Characteristic Points method and could be well fitted by Langmuir model. At lower temperature or lower density of mobile phase, the adsorption capacity increased, with the maximum being 70.10 kg/m³ for baicalein and 45.25 kg/m³ for wogonin. The diffusion coefficients of the baicalein and wogonin were determined by the Taylor-Aris peak broadening method. They decreased with higher pressure, lower temperature, or higher density of the mobile phase. This work offers basic data support for the design of SF-SMB systems and industrial platform technology.