Kinetics of static layer melt crystallization of honokiol

Honokiol （HNK） is a significant natural pharmaceutical active ingredient. To solve the problems of high solvent residue and low efficiency in its traditional purification methods, an efficient and green static layer melt crystallization purification process was explored. Focusing on the HNK melt crystallization process, this study established a mathematical model based on the heat transfer theory of boundary layer movement, solved the model using an analytical iterative method, and designed experiments for verification to study the kinetics of HNK static layer melt crystallization. In the study, the specific heat capacity, enthalpy of fusion, and thermal conductivity of HNK were measured, while the variation law of the solid-liquid phase interface temperature with the coolant temperature was considered. The results showed that the model could well predict the crystal layer growth trend under different coolant temperatures （79~83 ℃） and cooling rates （1~4 ℃·h⁻¹）. Decreasing the coolant temperature or increasing the cooling rate could significantly enhance the crystallization rate, with the best fitting effect achieved at a coolant temperature of 82 ℃ and a cooling rate of 2 ℃·h⁻¹. The conclusions provide a theoretical support for the optimization of high-purity melt crystallization processes and reactor design for HNK.