Sterlitech Newsletter - June 2011

 In This Issue…

• What's New in June?
• June Promotion - Save Big on Vacuum Pumps
• Carbon Nanotubes for RO Desalination
• FAQ: What's the Difference Between Cellulose Acetate and Regenerated Cellulose?
• Purifying Biodiesel Through Membrane Separation

What's New in June?

In June we're expanding our knowledge base with more detailed information on product applications, frequently asked questions, technical specs and more! If you've got a question or a topic you'd like for us to cover let us know by replying back to this email or bringing it up on Twitter (@sterlitech).

Carbon Nanotubes for RO Desalination
There have been some exciting developments recently in the field of reverse osmosis desalination. For years scientists have experimented with carbon nanotube (CNT) infused membranes that could theoretically improve the efficiency of RO desalination to the point where it could be viable as a large-scale water purification process. The current process is expensive and new membrane technology could dramatically lower costs to pave the way for more desalination plants.
 
Simulations have shown that CNT’s have 20 times greater water permeability (what’s this?) than current membranes. The CNT manufacturing process also allows the maker to chemically modify the material for improved salt ion rejection.

For more information you can read the most recent report, and also check out some of our blog posts on the topic (This one and this one).

Reduced Prices on Vacuum Pumps! Get pumped for summer with our huge savings on Rocker and Chemker vacuum pumps! Save hundreds of dollars on these models that you can put towards other filtration accessories. The Rocker series is for liquid vacuum filtration and stack or ambient gas sampling. The Chemker Teflon pumps are chemical-resistant and corrosion-proof for solid phase extraction, gel drying, and other filtration applications involving acidic, basic, or solvent vapors.   This sale is going on now until July 31st!

FAQ - What's the Difference Between Cellulose Acetate and Regenerated Cellulose?
Cellulose Acetate is a specific type of polymer used for low protein binding applications. The CA membranes we carry are made from cellulose diacetate (as opposed to mono- or tri-acetate).

Regenerated Cellulose on the other hand, is a pure cellulose which has been treated in a chemical bath for improved chemical resistance. It has a lower molecular weight and the structure is not as uniform as it is for other cellulose. An example of regenerated cellulose is "cellophane" used in a dialysis application for artificial kidneys.

Cellulose Acetate is a versatile material that is frequently used for sterilizing tissue culture media or biological fluids, and for protein recovery since it offers low protein binding. Regenerated Cellulose features better resistance to solvents so it is more often used for de-gassing and ultra-cleaning solvents, and for mobile phases of HPLC.

Purifying Biodiesel Through Membrane Separation
A membrane separation setup may improve the biodiesel purification process, according to a new study performed at the University of Ottawa. Researchers tested several membrane types in the ultrafiltration (UF) and microfiltration (MF) ranges and determined that a membrane separation system (which also included Sepa crossflow cells) could be used to remove glycerol from untreated biodiesel in accordance with ASTM quality standards.
 
As explained in ASTM Method D6584, “Free and bonded glycerin content reflects the quality of biodiesel. A high content of free glycerin may cause problems during storage, or in the fuel system, due to separation of the glycerin.” Glycerin appears in untreated biodiesel as a by-product of transesterification (when fats or oils are reacted with alcohol to produce untreated biodiesel). Conventional methods of biodiesel purification, such as water washing and ion exchange, often require copious amounts of energy and can be harmful to the environment, hence the need for an alternative process.
 
For this study, the University of Ottawa team tested glycerol separation with a modified Ultrafilic* polyacrylonitrile (PAN) membrane, with 100 kD (UF) molecular weight cut-off (MWCO), three types of polymeric UF membranes (PES, PVDF, and Ultrafillic) with varying MWCO, and also ceramic membranes of varying pore size in the UF and MF range. All of these membranes were purchased from Sterlitech.
 
After completing these tests the researchers concluded that a membrane separation process could meet ASTM standards for purification in a manner that is cost efficient and reduces environmental impact. They recommend continuing studies along this path with more membrane types to determine the most effective means of implementing membrane separation for future biodiesel production.

You can find the study "A Membrane Separation Process for Biodiesel Purification" on Science Direct or read the pdf version
View the ASTM Standard
*Ultrafilic is a trademark of GE Osmonics Inc.

Read the Sterlitech Blog for More News and Articles!
www.sterlitech.blogspot.com