Hybrid solar-electric thermal dehydration and oxidation of Cannabis sativa L. leaves. Prospecting of CBD, THC and CBN concentration

Abstract

This study presents a hybrid thermal dehydration and oxidation process (solar-electric) applied to Cannabis sativa L leaves, a common by-product of cannabis cultivation. The research aims to assess the viability of utilizing the leaves as raw material by quantifying the concentration of Cannabidiol (CBD), Tetrahydrocannabinol (THC), and Cannabinol (CBN). Experimental trials revealed that the thermal treatment not only effectively removes moisture but also induces desirable chemical transformations, particularly the oxidative degradation of THC to CBN while successfully preserving the CBD. The process was determined to comprise two distinct stages: an initial dehydration phase lasting 5 to 6 hours, followed by a final thermal oxidation phase. The quantitative results are significant: fresh leaves, initially containing 12 mg/g of CBD, reached final concentrations of up to 53.05 mg/g of CBD after 30 hours of thermal dehydration and oxidation treatment. This outcome suggests a substantial economic potential, as discarding the leaves implies a significant loss of active compounds, estimated at a 1:4 ratio (grams of CBD in floral apices relative to grams of CBD in treated leaves). Ultimately, this method is concluded to be an effective strategy for waste valorisation, thereby enhancing the sustainability and profitability of cannabis production.