Applications:
Supercritical fluids based technologies are involved in a wide variety of industrial applications which have shown significant progress in recent years. Many industrial sectors are concerned including food, cosmetics, pharmaceutics, materials, chemistry, energy and waste treatment.The related supercrical fluid processes include extraction, impregnation, formulation, sterilization, cleaning, energy and waste treatment among others.
Some example of the industrial applications based on the utilzation of supercrical fluids are listed below:
Food industry
The use of Supercritical CO2 as an extraction solvent for natural products is the oldest and the most developed process on an industrial scale, with applications especially in the food industry.
Other examples of industrial applications in the food industry include the production natural colorants and aromas, the elimination of pesticides, the extraction of lipids, the sterilization of milk and fruit juice, the deodorization of fish oil, the encapsulation of oils, treatment and valorization of food waste …
Cosmetic industry
Antioxidant such as polyphenols, carotenoids and tocopherols (vitamin E), which are found in a wide variety of fruits and vegetables (beta carotene in carrots, lycopene in tomato…) can be selectively extracted using supercritical CO2. In addition, the textures of the extracts obtained (thyme, rosemary, lavender, chamomile…) are free from traces of organic solvents.
Pharmaceutical industry
Among the spectrum of the extracts obtained from plants, diterpenes (antioxidants), triterpenes (phytosterols), or even the tetraterpenes (carotenes) which may be of interest to the pharmaceutical sector, can be easily extracted. Supercritical fluids may also be utilised for the production of fine powders, in particular for the formulation of active principles.
How It Works:
Supercritical Fluid Extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids as the extracting solvent. Extraction is usually from a solid matrix, but can also be from liquids. SFE can be used as a sample preparation step for analytical purposes, or on a larger scale to either strip unwanted material from a product (e.g. decaffeination) or collect a desired product (e.g. essential oils). These essential oils can include limonene and other straight solvents. Carbon dioxide (CO2) is the most used supercritical fluid, sometimes modified by co-solvents such as ethanol or methanol. Extraction conditions for supercritical carbon dioxide are above the critical temperature of 31 °C and critical pressure of 74 bar. Addition of modifiers may slightly alter this. The discussion below will mainly refer to extraction with CO2, except where specified.
Advantages:
- Single step extraction is tailored to achieve highly concentrated products.
- Extracts and spent biomass are free of solvent residues.
- Mild operating temperature ensures product stability and quality.
- Supercritical CO2 is universally accepted as a “friendly” and fully recyclable solvent.
- Product recovery is accomplished via a simple pressure reduction.
- Hazardous solvent wastes are eliminated.
- Compounds in a complex mixture can be selectively separated using the pressure dependent dissolving power of supercritical fluids.
- Supercritical fluids can penetrate and extract from micro-porous substrates because of gas-like diffusion properties and the absence of surface tension limitations.
- Lower operating costs are often realized because compression energy is more efficient than distillation energy.
- Large scale supercritical fluid extraction of low price, commodity items such as coffee, tea, and saw palmetto indicates that supercritical CO2 processing can compete economically with traditional extraction and separation processes.