CO₂ Extraction Explained

Supercritical CO₂ (SC-CO₂) extraction uses carbon dioxide above its critical point, where it behaves partly like a gas and partly like a liquid. It can move through plant material like a gas while dissolving aromatic and bioactive compounds like a liquid solvent.

The process, step by step

1. Loading: Raw botanical material is loaded into a pressurised extraction vessel.
2. Pressurisation: CO₂ is brought above its critical point, roughly 31°C and 74 bar, becoming a supercritical fluid.
3. Extraction: Supercritical CO₂ circulates through the material and selectively dissolves target compounds. Fractional separation can provide finer selectivity.
4. Separation: Pressure is reduced. CO₂ returns to a gas and separates from the extract; no chemical-solvent evaporation step is required.
5. Recovery: The CO₂ gas can be recovered and recompressed for reuse rather than released as waste.

Why pressure and temperature matter

Changing pressure and temperature changes what CO₂ can dissolve. Lower combinations favour light, volatile aromatics; higher combinations pull heavier compounds such as waxes and resins. This tunability lets one method serve very different applications.

Why this matters for procurement

Because no organic solvent such as hexane or ethanol enters the confirmed process, there is no organic residual solvent from the extraction step to manage in downstream safety documentation.