Biodegradable functional chitosan membrane for enhancement of artemisinin purification

Artemisinin is mainly derived from Artemisia annua L. Since the leaves composition is complex, artemisinin purification faces great challenges. In this work, functional chitosan membranes were fabricated by a one-step hydrolysis method through grafting long-chain alkyl group on the surface of chitosan to increase its hydrophobicity. The as-prepared membranes were used to adsorb wax oil (i.e., the impurity components) in Artemisia annua L. and to avoid co-precipitation of wax oil along with artemisinin using the crystallization technique for purification. Octyl-trimethoxysilane modified chitosan membrane (FCM-C₈) showed excellent capability to intensify this purification process. The product purity could reach more than 98 % using one crystallization step under the optimal conditions, and in this case, adsorption capacity of FCM-C₈ for wax oil was 478.9 mg/g. In addition, the adsorption kinetics and mechanism of wax oil on FCM-C₈ were studied. The membrane can simultaneously adsorb multiple components in wax oil through interactions like electrostatic forces, hydrogen bondings.