Integrated green processing for cannabidiol production: Supercritical CO₂ extraction followed by optimized thin-film distillation and crystallization

Supercritical carbon dioxide (scCO 2 ) extraction has emerged as a promising green technology for extracting cannabinoids because it does not require any solvents and is environmentally friendly. However, the resulting scCO 2 crude extracts often contain high levels of co-extracted impurities, such as waxes and pigments, which hinder direct crystallization and necessitate efficient downstream purification. Cannabidiol (CBD) is a pharmacologically significant cannabinoid; however, achieving high-purity production sustainably remains challenging. This study presents a comprehensive and eco-friendly biorefinery framework for CBD purification that integrates scCO 2 extraction with optimized thin-film distillation (TFD) and crystallization. Crude oil from the 'Pink Pepper' hemp variety, extracted using scCO 2 , was subjected to pretreatments followed by TFD optimization using response surface methodology (RSM) with a Box-Behnken design. Three independent variables, evaporation zone temperature, vacuum pressure, and feed rate were evaluated. The optimal TFD conditions were determined to be an evaporation temperature of 207.57 °C, a vacuum pressure of 0.050 mbar, and a feed rate of 37.47 Hz, achieving a CBD conversion rate of 68.05%. Under these conditions, CBD purity was significantly enhanced from 41.56% in the scCO 2 crude oil to 72.89% in the distillate, providing a refined feedstock for subsequent processing. High-purity CBD crystals (>99.0%) were successfully obtained through solvent-minimal crystallization using pentane at −10 °C. This integrated scCO 2 -TFD approach offers a robust and sustainable industrial paradigm for high-purity CBD production, significantly reducing reliance on organic solvents and highlighting the effectiveness of CO 2 -based processing in the cannabinoid industry.