Producing Nanoparticles Using Supercritical Fluids

The use of nanoparticles in all areas is ever increasing. While the existence of nanoparticles is not new, using Supercritical Fluids (SCF) to create them is.

Traditional means

Traditional means of making specifically sized material involves several techniques. These include:

• Milling
• Grinding or
• Crushing.

Unfortunately, each of these traditional techniques 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
  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.

Want to learn more? Contact us and we'll help you incorporate Green Chemistry with Supercritical Fluids into your processes!

Read about the other ways SCF is being used. Supercritical Fluids will change the way you work!

Applied Separations offers a full line of SFE systems to meet the needs in your laboratory.

Spe-ed SFE Prime
Applied Separations has created the first teaching tool for Supercritical Fluids. Safe and affordable, this instrument is perfect for the classroom.

Supercritical Fluids (SCF) Education
As thought-leaders in the world of Supercritical Fluids, Applied Separations strikes to share its knowledge and experience to further the use of Supercricial Fluids.

Laboratory Instruments
Applied Separations has the instruments you need in your laboratory to handle the most complex to the most straight-forward SCF projects.

Pilot Plants: Small Production
The basic supercritical pilot plant is a "no frills" caster-mounted system for the budgetminded. You, as the user, determine the size of the system...

Industrial Scale Production
Applied Separations will work with you to pin-point your needs and determine the feasibility of your project.

Metal Injection Molding
Supercritical Fluids will revolutionize the debinding process.

Accessories
Not only do we offer SCF instruments, but a full line of accessories the customize your SCF instruments are also available.

Applications
We have compiled a comprehensive list of SCF applications available for free. Click here to view the list of the SCF applications you can put to use immediately in your lab.

Let Green-I-Am introduce you to the world of SCF!

Virtual Video Warehouse What is Supercritical Fluid Extraction: A look at this green technology that uses SCF How to pack a vessel: Learn how to effectively pack a vessel for any of the Spe-edSFE instruments in our line. The Spe-ed SFE Prime from Applied Separations: Learn about this low cost instrument, created especially for the educational market. Teaching Environmentally Benign Extraction Technologies with a Cost Effective, User Friendly Instrument: This paper, presented at ACS 2008, describes the fundamentals of the supercritical fluid extraction process and the implementation of this environmentally friendly, green chemistry technique, using the low cost, student-friendly Spe-ed SFE Prime. The "Green" Extraction of Oils from Natural Products Using Supercritical Fluids: Learn how to use SCF for natural product extractions from this poster, presented at ACS 2008. SCF Product Line from Applied Separations: Check out the extensive line of Spe-edSFE instruments available from Applied Separations.    More on ASInteractive...

What is SCF? Carbon dioxide is in its supercritical fluid state when both the temperature and pressure equal or exceed the critical point of 31°C and 73 atm (see diagram). In its supercritical state, CO2 has both gas-like and liquid-like qualities, and it is this dual characteristic of supercritical fluids that provides the ideal conditions for extracting compounds with a high degree of recovery in a short period of time. 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. Because CO2 is non-polar, a polar organic co-solvent (or modifier) can be added to the supercritical fluid for processing polar compounds. By controlling the level of pressure/ temperature/ modifier, supercritical CO2 can dissolve a broad range of compounds, both polar and non-polar.