Leaching of cannabinoids from cannabis sativa flowers using a pH-controlled aqueous solvent: Study of important parameters

<p dir="ltr">This study investigates the leaching of cannabinoids, primarily in their acidic forms, from Cannabis sativa using a pH-controlled aqueous solvent. Key factors including the initial form of cannabis biomass (fresh vs. dry, ground vs. unground), solvent pH and ionic concentration (NaCl content), solid-to-liquid (S/L) ratio, leaching kinetics and temperature were assessed. The results indicated that the highest cannabinoid yield is obtained from fresh flowers, eliminating the need for drying and grinding, pre-treatment steps that are both time-consuming and energy-intensive. Peleg's model was applied to describe the leaching kinetics, demonstrating a high correlation (R²≥ 0.98) with experimental data. The model's parameters indicated rapid leaching, requiring less than 10 min for whole fresh and dried flowers and less than 30 sec for ground dried samples. Temperature analysis showed that heating was not preferred as elevated temperature converted acidic cannabinoids to neutral forms, lowering leaching yields. Thermodynamic analysis indicated an exothermic reaction. Additionally, salt addition of 0.5 % (w/v) NaCl to the pH 13.0 aqueous solvent enhanced the yield, while higher concentrations led to a sharp decrease in leaching yield due to cannabinoid precipitation. These findings demonstrate the efficiency of this method as a viable alternative for industrial cannabinoid extraction, reducing both energy use and process complexity.</p>