Ionic liquids simultaneously used as accelerants, stabilizers and extractants for improving the cannabidiol extraction from industrial hemp

Abstract

Recently, cannabidiol (CBD) has attracted more attention owing to its application in pharmaceuticals, food, cosmetics and other industries. However, the conventional organic solvents are still used as the common extractants in the CBD extraction. In this work, ionic liquids (ILs) were used as the alternative solvents for the CBD extraction. Simultaneously, ILs can be used as accelerants for promoting the conversion of cannabidiolic acid (CBDA) to CBD by decarboxylation. Moreover, ILs can enhance the stability of CBD in the extraction process. The factors affecting the extraction were investigated, including liquid-solid ratio, extraction time, and extraction temperature. The maximum extraction yield was obtained using 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][NTf2]) as the extractant under the optimal conditions, which is nearly double as high as that using methanol as the extractant. Further studies of density functional theory (DFT) had illuminated that ILs can accelerate the decarboxylation of CBDA owing to the solvation effect of ILs. Furthermore, the DFT calculations proved that ILs can prevent CBD from being degraded and enhance its stability by the weak interactions between CBD and its contactants. Finally, the back-extraction had been done for the recovery of CBD and recycling of ILs. This study provides a green and effective method for improving the extraction of CBD from industrial hemp.