Fitting of moisture adsorption models for Astragali Radix aqueous extract / 中成药

ABSTRACT

AIM To fit the moisture adsorption models for Astragali Radix aqueous extract.METHODS For the aqueous extract prepared by decocting,the moisture adsorption kinetics curve and adsorption/desorption isotherms were drawn by gravimetry,and then the data on moisture adsorption were fitted.The fitted models were optimized according to evaluation indices of root mean square error (RMSE),residual sum of squares (RSS) and coefficient of determination (R2).RESULTS The double exponential model for moisture adsorption kinetics curve and Peleg model for adsorption/desorption isotherms were considered as the two best models with regard to their fitting effects (R2 values were the closest to 1,RMSE and RSS values were the closest to 0).Among them,various adsorption/desorption isotherms all belonged to type Ⅱ ("S" isotherm),while the higher equilibrium moisture content of desorption isotherm than that of adsorption isotherm contributed to obvious type H3 hysteresis phenomenon.CONCLUSION Double exponential model and Peleg model can well fit the moisture adsorption kinetics curve and adsorption/desorption isotherms of Astragali Radix aqueous extract,respectively.