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Optimizing Supercritical CO2 Extraction: Understanding the Kinetic Curve and Biomass Characteristics

CBD Oil CO2 Extraction

In Supercritical CO2 extraction, the total cannabinoid content in biomass and its distribution play a crucial role in determining the required solvent volume and processing time. Understanding the kinetic curve, which encompasses three distinct stages, allows operators to customize their extraction runs based on the remaining target compounds in the biomass.

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The Three Stages of the Kinetic Curve

The kinetic curve comprises three stages: the Constant Extraction Rate (CER) stage, the Falling Extraction Rate (FER) stage, and the Diffusion Controlled (DC) stage. Each stage represents a unique phase of the extraction process and influences the overall efficiency.
Key points to consider:

  • Constant Extraction Rate (CER) Stage: In this initial stage, the extraction rate is high as the target solute molecules are predominantly located on or near the surface of the biomass particles. The solvent easily accesses and interacts with these molecules, resulting in a linear extraction phase.
  • Falling Extraction Rate (FER) Stage: As the CER stage progresses, the free surface solutes become depleted, and the unsaturated solvent starts saturating into the solid particles. The extraction rate gradually decreases during this stage, leading to diminishing yields.
  • Diffusion Controlled (DC) Stage: In the final stage, all the remaining free solutes have been extracted, and only the solutes bound within the biomass particles remain. This stage is highly inefficient, and minimizing the time spent in this phase is crucial for optimizing extraction processes.

Bud vs. Trim: Impact on the Kinetic Curve

The cannabinoid distribution and accessibility differ between cannabis bud and trim, leading to variations in the kinetic curve and extraction characteristics.
Key points to consider:

Bud Biomass: Cannabis buds contain a higher concentration of cannabinoids in the trichomes, making them easily accessible for the solvent. Consequently, bud extraction exhibits a longer CER stage, resulting in higher yields per unit of time. However, it requires more solvent and longer processing times.
Trim Biomass: Trim material has fewer cannabinoids on the surface, necessitating the solvent to diffuse deeper into the plant matter to solubilize the cannabinoids within. As a result, trim extraction shows a shorter, lower-yield CER stage and longer, more pronounced FER and DC stages.

Importance of Biomass Type and Cannabinoid Load

The type of biomass and its cannabinoid load significantly impact the total solvent required and overall run time for extraction. No standardized run time can be applied universally due to the variability of marijuana and hemp.
Key points to consider:

Optimizing Solvent Amount: Insufficient solvent volume may leave cannabinoids behind, reducing extraction efficiency. Conversely, excessively long extraction times may lead to wastage and inefficiency.
Analytics for Maximum Efficiency: Analyzing the initial biomass composition is crucial to ensure maximum efficiency and minimize cannabinoid loss. Relying on static run times without considering biomass characteristics and using analytics can result in unnecessary expenses and suboptimal extraction outcomes.
Decarboxylation Considerations: Decarboxylation, the conversion of acid forms (THCa or CBDa) into neutral forms (THC or CBD) through heating, affects extraction dynamics. Decarboxylated cannabis exhibits better solubility, enabling faster extractions. However, this method may degrade the terpene profile. Decarboxylation and preserving terpenes depend on the biomass type and desired end product.


Understanding the kinetic curve and the influence of biomass characteristics is crucial for optimizing Supercritical CO2 extraction. By customizing extraction runs based on the remaining target compounds, operators can enhance efficiency, yields, and product quality. Whether it’s a bud or trim biomass, considering the kinetic curve and cannabinoid distribution allows for informed decision-making regarding solvent volume, processing time, and potential decarboxylation. Integrating analytics throughout the extraction process ensures maximum efficiency and cannabinoid preservation.