An optimum ethanol-water solvent system for extraction of podophyllotoxin: Experimental study, diffusivity determination and modeling

Solvent extraction of podophyllotoxin was carried out with different ethanol-water solvent systems at various extraction conditions. Maximum extraction rate and yield were obtained with a solvent system of 30 ethanol/70 water (volumetric ratio) and 53 °C for all particle moisture contents. When temperature increased from 53 to 80 °C, the extraction yield of podophyllotoxin significantly decreased due to podophyllotoxin degradation. Particle moisture content had significant effect on yield only at 100% ethanol. Also radio frequency heating had no significant effect on yield and extraction rate within 30-55 °C. A diffusional mathematical model was developed and used to determine the effective diffusivity and partition coefficient of podophyllotoxin for 14 extraction conditions. A very good agreement between predictions and observations led to reliable estimations of the effective diffusivity and partition coefficient of podophyllotoxin.