Supercritical Fluid Extraction (SFE) is globally recognized as the most advanced physical separation technology. In SFE operation, the fluid transforms from a gaseous/liquid phase to a supercritical state. Utilizing the superior diffusivity and permeability of supercritical fluids, it thoroughly and uniformly contacts the raw material from the surface to the interior. Then, leveraging the excellent dissolving capacity of supercritical fluids, it fully mixes and dissolves with the target components in the raw material. The supercritical fluid, now fully mixed with the target components, enters the separation unit. Due to changes in environmental parameters, the supercritical fluid reverts to a gaseous state, breaking the previously good dissolution state with the target components. The gaseous fluid is expelled upwards through the pipeline, while the target components dissolved in it are completely separated from the gas and settle at the bottom of the container, thus obtaining the purest extracted components. 

Technical Features

Since the density of supercritical fluids is highly sensitive to changes in temperature and pressure, adjusting the pressure or temperature of the supercritical fluid, according to the principle of “like dissolves like”, alters the density of the supercritical fluid, thereby adjusting its dissolving capacity for the target components in the raw material. If the temperature remains unchanged beyond the critical point, merely changing the pressure can significantly increase the fluid's density (for example, the density of CO2 can be increased by more than six times), thus changing the fluid's dissolving capacity and turning it into a solvent with different dissolving properties. Therefore, supercritical fluid extraction is selective, allowing for the sequential extraction of different target components from the raw material by altering parameters.

The extracts obtained at various pressure or temperature ranges during the supercritical extraction process are all mixtures. Operators can control the appropriate proportions of the mixed components by adjusting parameter conditions. Adding a small amount of polar solvent to the supercritical fluid can also alter its dissolving capacity for solutes. 

Technical Advantages

Supercritical fluids can perform extraction at temperatures close to human body temperature, effectively protecting various heat-sensitive, low-boiling-point volatile or physiologically active components in natural products from damage. Compared to traditional solvent extraction methods using organic solvents or water, supercritical extraction offers higher or comparable yields, but the product composition is entirely different. The components extracted by supercritical methods are richer and closer to the original, authentic state of the components in the raw material. Moreover, supercritical extraction is selective, allowing operators to specifically extract a particular segment of components through parameter control. The products of supercritical extraction are of high purity, free from organic solvent residues. The industrial application process is simple, with short operation times, low energy consumption, no risk of flammability or explosion, and no emission of waste, making it internationally recognized as an “environmentally friendly” and “green” high-tech.