Controllable Design of Poly(ionic liquid) coatings for enhanced artemisinin purification

Artemisinin is primarily derived from Artemisia annua L. However, due to the complex composition of its leaf extract, the purification and separation of artemisinin remain a significant challenge. In this work, various poly(ionic liquid)s (PILs) containing polar ester groups and non-polar long-chain alkyl groups were synthesized through radical polymerization. Subsequently, these PILs were made into coatings with controllable pore sizes and adjustable hydrophobicity. The ethyl octadecanoate based PIL coating showed excellent capability to intensify this purification process. The product purity could reach 96.8% after one crystallization step under the optimal conditions, approximately 30.8% higher than the traditional method. And the product purity could reach 99.9% after three sequential separation processes. In addition, the adsorption kinetics of wax oil on the PIL coating were studied, and the results indicated that it followed a pseudo-first-order kinetic model with a maximum adsorption capacity of 226.33 mg/g. Mechanism analysis demonstrated that hydrogen bonding and van der Waals forces between the wax oil and PIL facilitated the adsorption of the wax oil, thereby increasing the purity of artemisinin.