Characteristics and Mechanism of Microwave-assisted Drying of Amorphous Paclitaxel for Removal of Residual Solvent

We investigated the characteristics and mechanism of microwave-assisted drying of amorphous paclitaxel for the removal of residual solvent, acetonitrile. The removal efficiency of residual acetonitrile increased with increasing drying temperature from 35 to 55°C. When the experimental data were applied to typical kinetic models, the Page model was determined to be the most suitable. Thermodynamic parameters revealed the spontaneous and endothermic nature of microwave-assisted drying. The effective diffusion coefficient of acetonitrile (0.865 × 10 −8 ∼ 1.553 × 10 −8 m 2 /s) and the convective mass transfer coefficient (2.138 × 10 −7 ∼7.656 × 10 −7 m/s) increased with increasing drying temperature. The small Biot number (0.001975∼ 0.003939) indicated that the process of mass transfer was externally controlled.