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If you've ever worked with a Polyamide flat sheet membrane, there's a good probability that you may have noticed some slight discoloration on the active layer side of the filter, as seen below:

And additionally, this may have caused some uneasy speculation; is it mold? contamination? time to purchase a new membrane?

The good folks at Toray Membranes were able to shed some light on this common concern... literally.

Brown discoloration can be due to small amounts of residual amine from the manufacturing process.  The amine, (one of the building block compounds used to create the polymer constituting  the polyamide membrane family),  can turn brown with exposure to sunlight.

This effect doesn't make for a pretty membrane,  but it does not affect the performance of the membrane in any way.

Note: if it is in fact mold that you're seeing, you can try irrigating the area with dechlorinated water with a laboratory wash bottle to see if it lifts off.  Any rubbing of the membrane surface should be kept to an absolute minimum, as there is the possibility to scratch or damage the integrity of the membrane layer. And again, while not pretty, the mold shouldn't affect the integrity of the membrane.

As we’ve brought up before, the Google Science Fair has turned out some amazing projects from 13-18 year-olds all over the world, and today Google announced the very deserving winners from each age group. Taking home the top prize is Shree Bose of Fort Worth, Texas whose project seeks to improve the effectiveness of chemotherapy treatment for ovarian cancer (you know, typical kids’ stuff). The techniques she uses, such as flow cytometry, microscopy and western blotting, will no doubt be familiar to many of our visitors.

Other winning projects covered the effects of environmental pollutants on asthma patients and methods for reducing carcinogens in our food. That all three of these winners were girls is an added bonus that will hopefully dispel some poorly conceived stereotypes about women in science.

All in all, there were some mind-bendingly impressive projects and the participants can look forward to bright futures as innovators in their chosen fields.

This study from the ACS journal Applied Materials & Interfaces has been making headlines recently for introducing a new way to purify drinking water. Scientists from Rice University have created a new filter material, dubbed “super sand,” by coating regular sand with the nanomaterial graphite oxide. Their tests have shown that this super sand has the potential to be a cheap form of water filtration for developing areas.

The use of sand as a water filter isn’t anything new – it’s actually been done for around 6,000 years. However, by combining this old world technique with cutting edge nanotechnology scientists have made sand filtration at least 5 times more efficient. Their report indicates that the modified sand adsorbed 6 times the amount of liquid mercury and 5 times as much heavy metal and organic dye than regular sand.

In addition to the improved filtration capacity, there are other benefits of super sand that increase its prospects for real-world integration. The materials needed to make super sand, graphite and regular sand, are inexpensive and readily available. Another crucial advantage is that super sand can be created around room temperatures. These factors lead experts to believe that super sand could become a cost-efficient and viable method of water filtration in the future.

Move over Copernicium! A collaboration of scientists from the Lawrence Livermore National Laboratory in California (one of our customers - we're so proud!), and the Joint Institute for Nuclear Research in Russia are being recognized today for officially creating two new elements! Scientists first created these elements in 1999 and 2000, respectively, by slamming lighter atoms together to see if they would stick. After a lengthy experimentation and review process by the International Unions of Pure and Applied Chemistry and Physics they are now certified and ready to take their rightful spots as the heaviest members of the periodic table.

Both of these elements are radioactive and exist for less than a second before decaying into lighter atoms. For now the elements are being referred to by their element numbers, 114 and 116, since the discovers are still in the process of submitting their recommendations.

It's probably a good thing that the naming process is limited only to the researchers that actually discovered the elements. Somehow I think if it was left up to an online poll our kids would be learning the atomic weight of "Bieberum."

Read more about the announcement here.

We all know oil and water don’t mix. Same goes for acids and bases. But what about Kerosene and cellulose acetate? Or Trichloroethylene and silver?

To answer these questions we have our frequently referenced Chemical Compatibility Chart for general laboratory filtration products. Since using the correct filter material is vital to the success of a separation process we are constantly expanding our knowledge base of chemicals used with our filtration products. We currently have data on over 70 chemicals and their recommendation level for filtration materials such as Polycarbonate, Nylon and Teflon.

Curious about a chemical that isn’t listed yet? Just ask us about it we’ll be happy to help you out.

According to a recent survey from Laboratory Equipment magazine on the usage of meters and monitors in lab experiments, most researchers do in fact trust their instrumentation; only 1% indicated that they were dissatisfied with their existing equipment. Another sign of trust: 71% of respondents plan to purchase direct replacements for their existing products when they buy new equipment.

You can take a look at these charts on what sort of meters and monitors are beings used and what they are being used for.

Scientists at Northern Illinois University recently published a new approach for fabricating hydrogen gas sensors by depositing palladium onto commercially available filtration membranes.  This creates networks of ultrasmall palladium nanowires without the traditional obstacles of nanofabrication (tedious production, potential contamination).  Palladium, besides poisoning Iron Man, is highly selective to Hydrogen gas and therefore commonly used in room-temperature solid-state Hydrogen sensors.

The new method involves a network of ultrasmall palladium nanowires (<10nm) being placed on 60 micron thick membranes with a nominal filtration pore diameter of 20nm. The end result is that this new type of fabrication method outperformed traditional hydrogen sensors, such as continuous reference film, by providing higher sensitivity and shorter response times. Better hydrogen sensing can lead to greater efficiency in areas such as steel manufacturing and clean energy research.

Have you ever wondered where you would be without Thomas Graham? If you are a chemist or membrane scientist, you probably should. Scientists of many disciplines are indebted to Thomas Graham for his groundbreaking studies on gas flow through microporous membranes. His work, which included creating Graham’s Laws of Diffusion to describe the relative permeation rate of two gases, was instrumental in the creation of colloidal chemistry and the advancement of membrane science.

In terms of real world applications, Graham’s efforts are a precursor to inventions ranging from the artificial kidney to the atomic bomb. His feats are even more impressive when you consider that in order to perform his experiments he had to first generate the necessary gases himself, and also that his selection of membrane materials was limited to whatever objects he could find, such as rubber balloons, animal bladders, and thin metal sheets.

Thomas Graham was born in Edinburgh, Scotland in 1805 and enrolled in the University of Glasgow at the tender age of 14! He went on to become Professor of Chemistry at Anderson’s College (now part of Strathclyde University) and then at University College London. In 1854, Graham was named Master of the Mint, a position once held by Sir Isaac Newton. Even though this was considered to be more of an honorary title at the time, Graham invested himself so heavily in its duties that he actually suspended his research for several years. The position was permanently retired following his death in 1869.

Thomas Graham’s influence has grown considerably since his passing. In addition to Graham’s Laws for diffusion and effusion of gases, he introduced the terms gel, sol, colloids, crystalloids, and dialyzer into the scientific lexicon. Other important contributions include his determining the formulas of the PxOy polyatomic ions, and in the 1850’s he hypothesized that a membrane machine could be created that would separate the blood toxins that built up in kidney failure, paving the way for modern kidney dialysis. His tenacity was rewarded with several honors in his lifetime, including the Copley Medal of the Royal Society, the Royal Medal of the Royal Society (twice), and the Prix Jecker of the Paris Academy of Sciences.

Sources:
“Thomas Graham,” D. Lane and J. Solon, Woodrow Wilson Leadership Program in Chemistry, The Woodrow Wilson National Fellowship Foundation, CN 5281, Princeton, NJ 08543; http://www.woodrow.org/teachers/ci/1992/Graham.html.

“Membrane Pioneers: Thomas Graham,” S. Alexander Stern and Richard W. Baker. Membrane Quarterly. Volume 25, Number 1, January 2010, pgs. 17-19.

Is nothing sacred? In the news today came word that the period table is changing the atomic weights of 10 elements. Instead of being listed as one static value, the atomic weight for these elements will now be displayed as a a range that will more accurately reflect how the elements actually appear in nature.

The change is being made after decades of study and this is the first time in the history of the periodic table that any atomic weights will be altered. Measuring the variance of atomic weights is being used in real world applications for everything from analyzing food purity, to determining which athletes are using performance enhancing drugs!

The elements being changed are: Boron, carbon, chlorine, hydrogen, lithium, nitrogen, oxygen, silicon, sulfur, and thallium.

I hope this doesn't mean we'll have to memorize the table all over again...

You can read more about the change here or here.

Here is an article that does a great job of explaining what efficiency ratings mean on a filter and how they are calculated, courtesy of the American Filtration & Separation Society.  This is very useful information for filter users and purchasing agents on the practical effects the filter efficiency will have in a real world setting.