Some folks still think that processing with supercritical fluids is not economical. Unfortunately, the general impression still exists among chemists and chemical engineers that supercritical fluid processing is associated with high costs. In reality, you only need to look at CO2-decaffeinated coffee and tea and CO2-extracted hops, which are being sold at prices competitive with their organic solvent extracted counterparts, and this fact alone contradicts the high cost association.
The erroneous association of high cost with supercritical fluid processes derived from the fate of several widely publicized (but ill-advised) studies in the late 1970s and early 1980s, when their lack of industrial viability was attributed solely to a "high processing cost." In actuality, there were technical limitations to the applications at the time and when they weren't industrially successful, it was easy to ascribe the blame to "high costs."
To sort out some of the economic misgivings, here's our take on the myths surrounding supercritical fluids, and the actual facts on the matter:
Myth: Supercritical fluid extraction is always more expensive.
Fact: Today, commodity items such as coffee, hops, and spices are processed by SFE and are economically competitive with traditional organic solvent extraction. Supercritical fluid extraction of nutraceuticals such as saw palmetto, antioxidants, and omega-3 concentrates can, in many instances, be even less expensive than traditional solvent extraction processes due to the elimination of solvent recovery steps.
Myth: Researching supercritical fluid applications is way too time-consuming.
Fact: SFE is simpler than traditional extraction processes, because clean-up and recovery of the SCF solvent occur in a single-step extraction.
Myth: You need your own processing equipment to take advantage of supercritical fluids.
Fact: Our ability to process 1,000, 10,000 or 100,000 kg campaigns enables our clients to evaluate supercritical fluids for their applications with no early-stage, high-risk capital investment. Let our expertise in Toll Processing provide you with rapid process/product development and scale-up, thus minimizing your costs and decreasing your time to market.
Supercritical fluids have been frequently proven to be excellent - often superior - solvents with far ranging attributes for many purification problems. If you are considering the application of supercritical fluids to your extraction, purification, or fractionation process, we can help you assess the merits completely free of charge. Try our No Cost Test today.
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In our line of work, we try to direct the many unique attributes of supercritical fluids to the solution of difficult processing problems across industries. We've worked with pharmaceuticals, foods, natural products, polymers, and fine chemicals. One day we will be extracting residual raw materials and solvents from medical polymers, and the next day, we'll be extracting volatile materials from high vacuum adhesives.
Today scores of large scale industrial applications have emerged, ranging from coffee decaffeination, to extraction of hops and nutraceuticals, to purification of medical polymers. At Phasex, we've done them all. Whereas supercritical fluid technology was once viewed as a "laboratory curiosity," it has earned credibility as an effective and efficient industrial operation around the world.
We often encounter completely new applications and, because we are supercritical fluids specialists, we know exactly when using supercritical fluids will be the best option. While applications vary, it is the unique combination of physical properties that afford supercritical fluids many unique capabilities when compared to traditional liquid solvents. Some of these physical properties and attributes are:
- Low viscosity
- Low diffusivity
- Liquid-like density
- Absence of surface tension limitations
- Absence of solvent residues
Supercritical CO2 and other gases have huge potential in many industrial applications because of these unique characteristics. We hear from people every day who are interested in learning more about supercritical fluid principles and practice. Usually the people we talk to are trying to figure out if supercritical fluids will help them achieve a goal such as increased yields or higher purity. Supercritical fluids can also help enhance characteristics of many different consumer or industrial products, and these products are always free of solvent residues. We offer the industry's only No Cost Test to help you learn if supercritical fluids will help you.
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More than 130 years ago, two Scottish researchers reported on an interesting phenomenon - that supercritical fluids could dissolve select compounds and that their dissolving power was pressure-dependent. This meant that the higher the pressure, the higher the dissolving power of these solvents. Subsequent work by the authors substantiated that a supercritical fluid can dissolve many compounds and that these principles apply to many gases and to organic compounds as well.
Slowly but surely, many research groups in the early 1900s studied the properties of supercritical fluids, investigating primarily thermodynamic phase behavior. Researchers kept expanding the list of supercritical gases and solutes. Finally, by the 1950s, the first description of a supercritical fluid extraction (SFE) process appeared in a US scientific journal. Meanwhile in Europe, especially in Germany, many engineers were spearheading the industrial development of SFE.
By the 1970s these processes were being applied to coffee production and beer brewing across Europe. Where chlorinated solvents had been used in coffee decaffeination, SFE decaffeination had the advantage of leaving behind no solvent residues and producing a superior flavor profile. In beer brewing, the hops flavor can come directly from boiled hops, or it can be derived more efficiently as an extract from hops using supercritical CO2 extraction.
These SFE decaffeination and SFE hops extraction processes are happening at industrial-scale production levels around the world. One plant in Bremen, Germany, decaffeinates coffee at 60,000 metric tons per year using supercritical CO2. A similarly large decaffeination plant exists in Houston, Texas. There are many hops extraction plans operating in Washington State, Europe, Asia, and Australia. Most of the world's decaf coffee is now decaffeinated with CO2, and most of the world's beer is flavored with CO2-extracted hops.
These clear successes in the application of SFE have motivated the further application of supercritical CO2 to a wide range of botanical and biological substrates, especially to nutraceuticals and essential oils. A cursory examination of the products at nutritional stores and a glance at the contents listed on the labels shows you the many products that contain or consist of supercritical CO2 extracts.
More than 100 million people in the US alone are using nutraceutical products. Consumers' strong belief in the efficacy of these products originates from a potent combination of modern-day science and ancient natural healing practice. Seeing the clear commercial opportunity, food marketers' have even created the "functional foods" category of enhanced beverages, snacks, and meals, to push nutraceuticals even further into the daily lives of consumers. Some Wall Street analysts have gone so far as to call the nutraceuticals industry "recession-proof" owing to its global reach in a world of consumers who are getting older and more concerned with their health.
What does this mean for supercritical fluids specialists? Through SFE we can gain phytosterols, carotenoids, xanthophylls, specialty lipids, and antioxidants, all from botanical, biological, and marine sources. A gas like CO2 can extract, concentrate, or purify these substances while at the same time producing an extract product with no solvent residues and no impact on the environment. With Americans spending $86 billion a year on nutraceuticals, these products are on track to become as common in our daily lives as coffee, tea, and beer. Supercritical fluid science is essential to the growth of this industry.
Photo credit: Bradley J
Even before testing supercritical fluid extraction on their products or raw materials, prospects frequently ask questions about costs and safety.
Q: Is supercritical fluid extraction (SFE) expensive compared to other extraction methods?
A: Today, commodity items such as coffee, hops, and spices are processed by SFE and are economically competitive with traditional organic solvent extraction. Supercritical fluid extraction of nutraceuticals such as saw palmetto, antioxidants, and omega-3 concentrates can, in many instances, be even less expensive than traditional solvent extraction processes due to the elimination of solvent recovery steps.
Q: Is SFE complex?
A: Customarily SFE is simpler than traditional extraction processes: simplified clean-up and recovery of the SCF solvent, single-step extraction yielding often highly concentrated actives due to high selectivity of CO2, and elimination of solvent residues in the product.
Q: Is high pressure operation hazardous?
A: With proper standard operating procedures and abiding by ASME standards, working at high pressure is a safe operation. Supercritical CO2 plants have been in operation in the US, Europe, and Asia since the late 1970s. Additionally, CO2 is non-toxic and non-flammable, unlike many organic solvents.
Q: Will CO2 emissions from SFE processes contribute to global warming?
A: Industrial scale SFE does not generate any CO2. The CO2 used for SFE is sourced from existing processes such as fermentation, and, thus, does not add emissions.
Q: Is SFE equipment expensive?
A: As in any commercial operation, equipment costs depend on many factors such as plant size and throughput, operating conditions, feed characteristics, markets, and selling price. Case-by-case economic evaluations point out the commercial viability of products produced by SFE.
Q: Will the SFE be too harsh on my material?
A: Extractions can be carried out at much lower temperatures as compared to other separation or purification methods, such as molecular distillation and wiped film evaporation. CO2 extraction is often the preferred method for sensitive raw materials products.
Phasex Corporation has developed a series of Top Ten Lists that provide interesting information and insight about supercritical fluids; this one is about Applications and we continue to Discover What's Possible.
- Medical Polymers - Residual monomers/by products are extracted near ambient temperature avoiding polymer degradation.
- Nutraceuticals (phytosterols, carotenoids, specialty oils) - Concentrated active fractions are produced with simple sequential pressure reduction eliminating multiple solvent/distillation steps.
- Implantable Tissue Scaffolds - Lubricants and surfactants are extracted without degradation of fiber networks.
- Titanium and Ceramic Implants - Machining oils and lubricants are removed from porous surfaces without the use of detergents.
- Reactive/heat labile compounds - Extraction of residual raw materials and by-products is accomplished near ambient temperature, eliminating possible reactions during high vacuum, high temperature wiped film evaporation.
- Omega-3 Oils (EPA, DHA, GLA) - Extraction from yeast, fungal, botanical substrates using CO2 eliminates regulatory, technical, and purity issues present with hexane/heptane solvent processes.
- Pharma and Agricultural Compounds - Nanoparticles are formed free of grinding media and surfactants.
- Biofuels - Solvent-free extraction of products from sustainable sources.
- High Performance Surfactants and Lubricants - Extraction of impurities and fractionation can tailor product properties and improve performance.
- Advanced Materials - Deposition of coatings onto surfaces and impregnation of APIs into porous substrates are accomplished with no diffusional limitations.
Phasex Corporation has developed a Top Ten List providing interesting information and insight about supercritical fluid extraction services.
- 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.