FILTERED FUME ENCLOSURE SAFETY continued


protecting the main filters from contaminants (Figure 3). A back-up safety filter offers additional protection. Safety is guaranteed by meeting and exceeding all requirements of OSHA and ANZI Z9.5 standards.


High-capacity carbon filtration


High-capacity activated carbon and specially treated carbon filters are also available for the containment of fumes and vapors in the most demand- ing applications. Although activated carbon can be manufactured from a variety of raw materials, only activated carbon derived from high-grade coconut shell is used in ISOLA filtered chemical workstations. High- temperature steam activation of coconut shell carbon leads to a slow and controlled destruction of the solid carbon mass, producing millions of pores. It is the microporous nature of this carbon product that ensures an extremely large internal adsorption surface. This steam-activated car- bon is effective in adsorbing most commonly found organic compounds from the air, including aliphatic and aromatic hydrocarbons, solvents, or- ganic acids, aldehydes and ketones, alcohols, esters, and many halogen and nitrogen compounds.


Some substances are not physically adsorbed by activated carbon, such as lower-molecular-weight compounds and inorganic gases. To address this, special impregnated chemisorptive carbon filters are recommended for the treatment of chemically reactive gases. These treated carbon filters combine a chemical reaction with the carbon’s adsorptive activ- ity, thereby breaking down compounds into their individual elements for easy adsorption. In essence, the addition of impregnates, such as a neutralizing or oxidizing agent, enhances the rate and effectiveness of adsorption. Even compounds with low adsorption ratings—such as ammonia, hydrogen sulfide, inorganic acid vapors, radioactive iodine, mercury vapors, and formaldehyde—can be effectively trapped and


rendered harmless by means of the chemisorptive carbon filters. In addition, there are specialized filters for sulfur compounds, where the activated carbon is impregnated with sodium sulfate to enhance chemi- cal adsorption.


HEPA filters


While standard filtered fume enclosure applications, such as contain- ment of acid spills or protection from harmful fumes, require both pre-filter and carbon filtration, high-efficiency particulate air (HEPA) filters are also available for specified cleanroom applications. Originally developed by the military for nuclear particle filtration, HEPA filters are specially designed air-cleaning devices that demonstrate filtration ef- ficiencies of 99.97%, for removal of particles ≥0.3 microns in diameter. Used in combination with pre-filters, HEPA filters are an effective way to capture particulates in smoke, dust, fingerprinting powders, asbestos, mold spores, bacteria, and other pathogens and high-risk cleanroom substances. The Mystaire portfolio of products combines active carbon filters with HEPA filters, enabling users to combine effective hazard containment with demanding cleanroom requirements.


Conclusion


When deciding upon a suitable filtered fume enclosure for the laboratory, each of the factors discussed should be considered. A well-designed ductless filtered fume enclosure will provide a safe and effective means of containing a wide range of fumes and applicable powders and particu- lates. The overall benefit is operator safety, environmental protection, and improvements in the overall function and efficiency of the laboratory.


Science News continued from page 8


Nanoparticle-Infused Wood Filters Impurities From Water


Engineers from the Maryland NanoCenter developed a method that uses wood to remove toxic dyes from water. They soaked a block of linden wood in palladium, which bonds to particles of dye. The wood’s natural channels, which once transported water and nutrients between the leaves and roots, now allow the water to flow past the nanoparticles for efficient removal of the toxic dye particles. The water, tinted with methylene blue, slowly drips through the wood and emerges clear. “We are currently working on using a wood filter to remove heavy metals, such as lead and copper, from water,” explained Liangbing Hu, professor of materials science and lead researcher on the project. “We are also interested in scaling up the technology for real industry applications.”


AMERICAN LABORATORY 46


Cinnamon May Reduce Effects of High-Fat Diet


A new study from the American Heart Association found that cinnamon stimulates antioxidant and anti-inflammatory systems and retards the body’s fat-storage process, thus lowering the risk of cardiovascular damage. One group of rats were given cinnamon supplements for 12 weeks in conjunction with a high-fat diet; the other group had high-fat foods with no supplement. The group that received cinnamon weighed less and had less belly fat and healthier levels of sugar, insulin, and fat in their blood than those that were not fed cinnamon. In addition, the animals that were given cinnamon had fewer molecules involved in the body’s fat-storing process and more antioxidant and anti-inflammatory molecules, which protect the body from the damages of stress.


JUNE/JULY 2017


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