Optimization of wiped-film short path molecular distillation for recovery of cannabinoids from cannabis oil using response surface methodology

Abstract

Few studies have explored the molecular distillation techniques that can improve the recovery of cannabinoids from crude cannabis oil with scale-up potential. Wiped-film short path molecular distillation is commonly employed in the cannabis industry for separating cannabinoids from terpenes and heavy compounds. It is a two-cut process, where the distillation of terpenes and cannabinoids occurs at the first and second cuts, respectively. In this experiment, the effects of the distillation parameters in the second cut, including feed flow rate (35–55 Hz) (41.6–71.3 mL min−1) and internal condensation temperature (60–90 °C), were examined and optimized using a central composite rotatable design towards maximizing cannabinoid mass and recovery efficiency in the distillate and minimizing cannabinoid mass in the residue. Results show that irrespective of internal condensation temperature, reducing feed flow rate increased the cannabinoid's yield and recovery. Although long distillation time was observed at low feed flow rates, the quality of cannabinoids remained unaffected. Response surface methodology was used to optimize the wiped-film short path molecular distillation of cannabis oil. The predicted optimal conditions were a feed flow rate of 35 Hz (41.6 mL min−1) and an internal condensation temperature of 75 °C. At these optimized conditions, the recovery efficiency of tetrahydrocannabinol was 93.4% in the distillate. To this end, this study provides distillation conditions to be considered by the cannabis industry if aiming for a cannabinoid-rich distillate from the molecular distillation process without affecting cannabinoid quality.