Pressurized Liquid Extraction of Hemp Residue and Purification of the Extract with Liquid-Liquid Extraction

The first semi-continuous Pressurized Liquid Extraction (PLE) of hemp threshing residue with ethanol was carried out according to a 32 full factorial experimental design with pressure and temperature as independent variables at 8-10-12 MPa and 323-333-343 K, respectively. The total-and cannabidiol (CBD) yield curves were fitted to the modified two-parameter Brunner equation. Best results, concerning CBD, can be achieved at 12 MPa and 343 K. Solvent mass-consumption and operation time were considerably decreased compared to a previous supercritical fluid extraction study on the same material. Furthermore, the concentration profiles were evaluated to study the mass transfer. The winterized dry extracts were further studied in a methanol-hexane-water ternary system concerning CBD distribution ratio, showing high methanol dependency.

Automated summary

The study conducted the first semi-continuous Pressurized Liquid Extraction (PLE) of hemp threshing residue with ethanol, achieving high CBD yield and efficiency. Results showed that the optimal CBD yield can be achieved at 12 MPa and 343 K under certain pressure and temperature conditions. Moreover, compared to the previous supercritical fluid extraction method, solvent consumption and operation time were significantly reduced.