Green Chemistry: Recycle Your Solvents

Everyone is making an effort to be environmentally friendly. We recycle our glass, cans, and newspapers, we take our travel mugs to the coffee shop, and take cloth bags to the grocery store… why not recycle solvents? Wait, recycle solvents?

Instead of using traditional solvents, which are costly and really cannot be recycled, use supercritical carbon dioxide. Carbon dioxide is one of the most commonly used supercritical fluids. CO₂ is:

• Safe
• Inexpensive
• Readily available
• An ideal substitute for many hazardous and toxic solvents

By controlling or regulating pressure and temperature, the density, or solvent strength, of supercritical fluids can be altered to simulate organic solvents ranging from chloroform to methylene chloride to hexane. This dissolving power can be applied to purify, extract, fractionate, infuse, and recrystallize a wide array of materials.

CO₂ is not produced in the SCF process. Existing CO₂ is used. There is NO addition to the greenhouse effect.

For more information about how you can use green chemistry for your process, visit the Applied Separations website.
http://appliedseparations.com/Supercritical/

“Green” Alternative to Soxhlet for Fat Determination in Food

Supercritical fluid extraction (SFE) was used to determine total fat and fat-soluble vitamins in Parmigiano cheese and salami. The results were compared with results obtained by traditional methods (Soxhlet). The quantity collected by SFE was statistically equivalent to the Soxhlet extraction.

For more information about the process or the specific application, contact Applied Separations
or visit the SCF section of the Applied Separations website.

Medical Implant Cleaning Using Supercritical Fluids

Today’s modern medicine allows many of us to have longer, healthier and more productive lives than our ancestors ever could have dreamed. One key part of this advancement is the use of medical implants that are made to replace and act as a missing biological structure within the body. Since the implants are placed inside the body, the cleanliness of the implant must be beyond compare. Contaminants can be introduced into the implant both in the processing of the implant and in the post-production handling.

For more information about cleaning medical implants with supercritical fluids, visit the SCF section of Applied Separations' website.

http://appliedseparations.com/Supercritical/SCF_Uses/SCF_for_Medical_Implant_Cleaning.asp

Using Supercritical Fluids to Dry Aerogels

Aerogels are highly porous materials with large internal surface area and large pore volumes. Their densities are as low as 3 kg/m3 and have porosities as high as 99.9%. This makes them excellent thermal insulators. In fact, aerogels are listed in the Guinness Book of World Records for the being the best insulators and the lowest-density solids.

In addition to their thermal insulating capabilities, aerogels have structural strength and impressive load-bearing ability, exceptional absorptive properties, and acoustic insulating capabilities. A short list of specific applications:

• Thermal insulation to windows and skylights
• Chemical absorber for cleaning up spills
• Thickening agents in paints and cosmetics
• Commercial manufacture of aerogel "blankets"
• NASA used aerogels to trap space dust particles aboard Stardust spacecraft
• NASA also used aerogel for thermal insulation of the Mars Rover space suits
• US Navy is evaluating aerogel undergarments as passive thermal protection for divers
• Use as a drug delivery system due to its biocompatibility. (Due to its high surface area and porous structure, drugs can be adsorbed from supercritical CO₂)

For more information, visit the SCF for Aerogels page.
http://appliedseparations.com/Supercritical/SCF_Uses/SCF_for_Aerogels.asp

New Papers Posted to ASinteractive Section of the Website

Applied Separations recently exhibited their Solid Phase Extraction and Supercritical Fluid product lines at Pittcon in Orlando. In addition, Applied Separations presented several papers. Reprints of the papers are posted to the ASinteractive section of the Applied Separations website.

• Metal Artifact Preservation Using the Subcritical Water Extraction Technique
http://appliedseparations.com/ASInteractive/Posters/pittcon10/asi_hunley.pdf
• A New Instrument to Teach “Green Chemistry” Analytical Techniques in Food Science Using the Example of the Determination of Total Fat in Snack Foods
http://appliedseparations.com/ASInteractive/Posters/pittcon10/asi_hunley.pdf
• Supercritical Fluid Extraction of Irganox 1076 and Irgafos 168 from Polyethylene
http://appliedseparations.com/ASInteractive/Posters/pittcon10/asi_scf_irgafos_poly.pdf
• Supercritical Fluid Deposition of Metals on Polymer and Composite Materials
http://appliedseparations.com/ASInteractive/Posters/pittcon10/asi_scf_metal_poly.pdf

Producing Nanoparticles Using Supercritical Fluids

Traditional means
Traditional means of making specifically sized material involves several techniques. These include:
• Milling
• Grinding or
• Crushing

But each of these has problems such as thermal and chemical degradation. Crystallization by adjusting supersaturation, using anti-solvents, or employing reactions and precipitations also have shortcomings:
• Product contamination
• High energy requirements
• Waste solvents
• Low yields
• Non-uniform particles

Using Supercritical Fluids
The use of Supercritical Fluids to make particles eliminates these shortcomings. There are number of SCF techniques to produce particles of controlled size and morphology for organic molecules in the sub micron range:
• RESS-Rapid Expansion of a Supercritical Solution
• GAS- Gas Anti-Solvent
• PCA- Precipitation by Compressed Fluid Anti-Solvent
• SEDS -Solution Enhanced Dispersion of Supercritical Fluids

RESS-Rapid Expansion of a Supercritical Solution
With RESS, material is dissolved in the SCF and then depressurized though a nozzle.

GAS- Gas Anti-Solvent
Here the compound is dissolved in an organic solvent, a supercritical fluid is introduced, expanding the volume and lowering the solvents solvent strength causing the compound to precipitate under controlled conditions of particle formation.

PCA- Precipitation by Compressed Fluid Anti-Solvent
With PCA, the compound dissolved in an organic solvent is sprayed into a SCF, casuing supersaturation and solute precipitation.

SEDS -Solution Enhanced Dispersion of Supercritical Fluids
Using SEDS, the compound is dissolved in an aqueous solution and the simultaneously sprayed through a coaxial nozzle with an organic solvent into the supercritical fluid. The water is dissolved into the solvent and SCF causing supersaturation and precipitation.

Nanoparticles of inorganic compounds can also be produced using supercritical fluids and sub-critical fluids. Thermal decomposition and hydrothermal syntheses are but two ways to accomplish this.

Applied Separations can provide you with the means to make both organic and inorganic particles.

Using SCF to Create Biofuel

Recently, yourgreenlife.org posted an article about Biofuels, which are currently one of the most discussed renewable fuel sources. One of the alternative fuel sources being researched is Biodiesel algae.


Supercritical fluids are being used as one of the methods of removing the oil from the algae. SCF removes 100% of the oil from the algae.


To read the full article:


http://www.yourgreenlife.org/2010/02/renewable-fuel-sources-biodiesel-algae/