Isotherm, Kinetic, and Thermodynamic Studies for Negative Pressure Cavitation Adsorption of Paclitaxel from Culture Supernatants of Taxus chinensis onto Diaion HP-20

Abstract

In this study, a negative pressure cavitation adsorption method was developed to efficiently recover paclitaxel from Taxus chinensis culture supernatants using Diaion HP-20 as an adsorbent. The equilibrium adsorption data were applied to Langmuir, Freundlich, Dubinin–Radushkevich, and Elovich isotherms, and the Langmuir isotherm was found to be the most feasible. The kinetic data were in good agreement with the pseudo-second-order model, and intraparticle diffusion played a dominant role in the adsorption rate of paclitaxel according to the intraparticle diffusion model. The time for the adsorption to reach equilibrium was shortened by more than eight times at all negative pressures (− 50 to − 200 mmHg) compared to the conventional adsorption. In addition, as the negative pressure increased, the maximum adsorption capacity, adsorption rate constant, intraparticle diffusion rate constant, and intraparticle diffusion coefficient increased. The values of the thermodynamic parameters indicated that the adsorption was endothermic and spontaneous. As the negative pressure intensity increased at a given adsorption capacity (q_e = 60–100 mg/g), the isosteric heat of adsorption decreased and the adsorbent surface became more energetically homogeneous.