Utilisation of supercritical fluids for the effective extraction of waxes and Cannabidiol (CBD) from hemp wastes

Up to 33% of hemp by mass can be lost in the form of dust during processing for fibre production. Heptane Soxhlet extractions and supercritical carbon dioxide extractions (scCO2) of hemp dust samples yielded significant quantities of high value lipophilic molecules including fatty acids, policosanols (fatty alcohols), fatty aldehydes, hydrocarbons, sterols, triterpenoids and cannabinoids (cannabidiol (CBD)). Dust collected from different stages of the mechanical processing of hemp fibres gave rise to lipophilic extractives with varying compositions, thus making the isolation and purification of these compounds easier. Of particular interest is CBD (5832.5 ± 118.9 μg/g of dust), which has attracted much attention for clinical-level studies due to its therapeutic efficacy in the treatment of a variety of central nervous system (CNS) disorders. Factorial experimental design was carried out to optimise the scCO2 extraction, with 350 bar and 50 °C yielding the selective extraction of higher value components.