Experimental optimization of a short-path distillation of alcoholic extracts from hemp

• Short-path distillation of ethanol extracts of Sannabis sativa were conducted. • Simplex design was experimentally implemented to optimize the process. • Operating pressures was the key variable to ensure high CBD recovery. • Under optimal conditions, 97% recovery of CBD and 95% cannabinoids were obtained. • Final distillate contained nearly 90 wt.% CBD. Short-path vacuum distillation is a key step for the recovery of high purity cannabinoids from cannabis extracts. Although the technique is readily available, it requires strict control to ensure efficient solvent recovery, high purity of terpene and cannabinoid fractions, minimal thermal degradation, and reduced energy use. This study presents an experimental optimization of short-path distillation for cannabis extracts using a simplex design. Ethanolic extracts from a non-psychoactive cannabis variety grown in Colombia were processed to maximize cannabidiol (CBD) and cannabinoids concentration and yield. Operating variables of the short-path distillation process included pressure (< 20 kPa), heating ramp (0.5–1.5 ºC/min), and Vigreux column length expressed as the number of indentations (2–4). Optimal conditions were reached after seven experiments, and they corresponded to a working pressure of 1.33 kPa, a heating rate of 1 °C/min, and using 3 rows of Vigreux points. Under these conditions, it was found that, by processing an ethanolic extract containing 3.6 wt.% CBD and 0.2 wt.% THC, it was possible to reach a 97% recovery of CBD, a total recovery of cannabinoids of 95%, with a distillate containing nearly 90 wt.% CBD. Obtained results could be used for further process modeling and development of optimal control strategies.