Subcritical CO2 Extraction of Cannabidiol from Hemp
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Solution Overview
Problem
Existing methods for extracting cannabidiol (CBD) from hemp are inefficient, costly, and can damage the product due to harsh extraction conditions, leaving toxic residues or imparting unwanted flavors, while existing supercritical carbon dioxide methods require harsh conditions for less soluble acid forms, risking degradation.
Innovation Solution
A method using subcritical liquid carbon dioxide at mild conditions (65 bars, <31°C) followed by separation on inert supports like celite, alumina, or silica, to extract and purify CBD, converting acid forms to neutral forms before extraction, and using sequential supercritical carbon dioxide for further separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional distillation extraction is used, then CBD oil can be separated from hemp plant extract, but the CBD oil is damaged by heating necessary for the process
Solution Approach 1:
The patent changes the extraction parameters from thermal-based distillation to pressure-based supercritical fluid extraction. By using supercritical carbon dioxide at elevated pressures (73-300 bars) and controlled temperatures (31-40°C), the process achieves CBD extraction without requiring the high heating temperatures that damage CBD oil integrity during conventional distillation.
Solution Approach 2:
The patent replaces the thermal-mechanical distillation system with a supercritical fluid extraction system. Instead of using heat and mechanical separation, the process uses supercritical carbon dioxide's unique physical properties (combining gas-like diffusivity with liquid-like solubility) to selectively extract CBD compounds from hemp plant material, avoiding thermal damage.
2Productivity
If hydrocarbon solvents are used for extraction, then the process is inexpensive, efficient and consistent, but toxic residues are left
Solution Approach 1:
The patent changes the solvent parameter from hydrocarbon-based to carbon dioxide-based extraction. By adjusting CO2 pressure and temperature parameters to achieve supercritical or subcritical states, the process maintains high extraction efficiency while eliminating toxic residues, as CO2 is inert, non-toxic, and can be easily separated from the extract by pressure reduction.
Solution Approach 2:
The patent uses carbon dioxide as a temporary, disposable extraction medium that can be safely discarded or recycled. Unlike hydrocarbon solvents that leave persistent toxic residues, CO2 serves its extraction function and then simply needs to be depressurized and vented, eliminating contamination issues.
3Productivity
If natural solvents are used for extraction, then the process is inexpensive and fairly efficient, but chlorophyll taste is imparted and lower CBD concentration is produced
Solution Approach 1:
The patent changes the extraction parameters by using supercritical or subcritical CO2 at specifically controlled temperatures (31-40°C) and pressures (73-300 bars). These parameter controls enable selective extraction of CBD compounds while excluding chlorophyll and other unwanted plant materials, achieving high CBD concentration without chlorophyll contamination.
Solution Approach 2:
The patent applies local quality by selectively extracting specific compounds (CBD) while excluding others (chlorophyll, fatty acids) through controlled supercritical fluid conditions. The supercritical CO2's tunable solubility parameters allow it to selectively interact with CBD molecules while leaving chlorophyll and other compounds in the plant matrix.
4Quantity of substance
If supercritical carbon dioxide extraction is used on acid forms CBDA and THCA, then extraction can be carried out, but harsh conditions are required which could damage or degrade the extracted products
Solution Approach 1:
The patent applies preliminary action by performing decarboxylation of the hemp plant material before supercritical CO2 extraction. This preliminary thermal treatment (typically 100-200°C for 1-3 hours) converts the acid forms (CBDA, THCA) into their neutral forms (CBD, THC), which are much more soluble in supercritical CO2, thereby enabling extraction under milder conditions that preserve product integrity.
Solution Approach 2:
The patent changes the extraction parameters by first modifying the chemical form of the target compounds through decarboxylation. This preliminary chemical change enables subsequent extraction at lower pressures and temperatures compared to extracting the acid forms directly, reducing the harshness of the extraction conditions and protecting the extracted CBD from degradation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves high extraction efficiency (>90%) and purity of CBD, removing THC and other cannabinoids, while minimizing degradation and residue, with a cost-effective and safe process.
Implementation Method 1
extracting cannabidiol from hemp with carbon dioxide... extraction can be carried out by distillation... or with a solvent... subcritical liquid carbon dioxide
Implementation Method 2
separation of the extract... sequential supercritical carbon dioxide for further separation... depressurisation, thereby returning carbon dioxide to gas state
Data Source
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AI summary
The present invention discloses a method for extracting cannabidiol from dried, milled and decarboxylated hemp by submitting to a subcritical liquid carbon dioxide extraction followed by a mild liquid carbon dioxide separation.