Research On Dynamic Of Extraction Diosgenin By Supercritical Fluid

According to the principle of mass conservation, the dynamic model of SCF-CO₂ is set up on differential extraction base on determining the extracted conditions. The influence of every factor to supercritical SCF-CO₂ is analyzed, and the main parameters of these models are discussed.The paper is composed of four parts:1)The extraction of diosgenin from dioscorea particle using supercritical carbon dioxide is investigated. The extraction rate is analyzed as a function of the extraction pressure, temperature, flow rate and particle size distribution through the orthogonal and single factor experiment2)The experiment results show that the extraction pressure and temperature have a crossover effect on extraction rate. The augment of temperature is good for extraction rate rising when the pressure is smaller than 30MPa. But when the pressure is bigger than 30MPa, there is a contrary phenomenon. The flow rate, particle size distribution and void fraction of the extraction bed have the complicated effect.3)Based on the broken-intact cells model, a dynamic model based on differential mass balance equation is developed according to the law of conservation mass. The expression of mass transfer flux is given by the analysis the process and the necessary hypotheses. The extraction process is described, and the expression of extraction rate of diosgenin is given。4)The main parameters of models include density of supercritical CO₂ fluid, solubility of supercritical CO₂ fluid, viscosity of supercritical CO₂ fluid, diffusion coefficient of solute in supercritical CO₂ fluid, bed void age, density of insoluble solid, velocity of flow of supercritical CO₂ fluid and equilibrium constant. The calculation methods and experiment data of parameters are given.