Efficiency Leap in Separating Para-xylene Using New Carbon Membranes The petrol industry recognizes the importance of para-xylene, given its many uses in everyday products, from plastic soda bottles to polyester fiber. The challenge is that xylenes travel in threes and are virtually identical, making it extremely difficult to efficiently separate and purify para-xylene from its less used siblings such as ortho-xylene. These molecules’ size differs by one-tenth of a nanometer. However, membranes with tiny pores engineered to differentiate these molecules can potentially enable this important separation. Georgia Tech researchers have uncovered new insights into the fab-
thin layers of materials in such a way as to drive off all the atoms other than carbon, resulting in a charcoallike substance that has moleculesized holes. In 2016, researchers at Georgia Tech and Exxon Mobil first demonstrated that a new carbonbased molecular sieve membrane could successfully separate xylene molecules and extract the super-useful para-xylene from the pack. Now rication of carbon membranes that have the potential to drive significant they have advanced this work. “We have made more stable macost savings once the solution for terials by changing the polymer prexylene isolation separation is scaled cursor we use. Then by changing how for industrial use. we transform the polymer into the The work, published in the Proceedings of the National Academy of carbon, we’ve made the membranes more productive,” said Associate Sciences, focuses on “carbon-based Professor Ryan Lively. molecular sieves,” made by heating
Covid-19 Mask Study Finds Layering, Material Choice Matter Wearing a face mask can protect you and others from Covid-19, but the type of material and number of fabric layers used can significantly affect exposure risk, a Georgia Tech study found. The study measured the filtration efficiency of submicron particles passing through a variety of different materials. For comparison, a human hair is about 50 microns in diameter while 1 millimeter is 1,000 microns. “A submicron particle can stay in the air for hours and days, depending on the ventilation, so if you have a room that is not ventilated or poorly ventilated, then these small particles can stay there for a very long period of time,” said Associate Professor Nga Lee (Sally) Ng. Published in Aerosol Science and Technology, the study was conducted during spring 2020, when the pandemic triggered a global shutdown of most institutions. Communities faced massive shortages of personal protective equipment, prompting many people to make their own homemade masks. Georgia Tech quickly set up the study since it already had “a great system for testing filtration efficiency using existing instruments in the lab,” Ng said.
Biomolecular Engineer Wins Grant to Make MicroorganismInspired Machines What do the cylinder in an internal combustion engine and the four-millimeterlong creature, Spirostomum ambiguum, have in common? Surprisingly, quite a bit. Both are similarly shaped. Both shrink to a fraction of their size in an instant. And both release about the same amount of power output per cubic centimeter in volume. But for all we know about the engine, we know relatively little about the living organism. Assistant Professor Saad Bhamla recently received an Outstanding Investigator Award from the National Institute of General Medical Sciences, part of the National Institutes of Health, to continue studying Spirostomum and attempt to build machines based on similar principles. The grant will provide his research group with $1.98 million in funding over five years. For Bhamla, the comparison between the organism and the engine is more than just an analogy. He is now working to build something directly akin to a micro-engine, with pistons and cylinders made out of synthetic cells similar to Spirostomum. CHBE.GATECH.EDU
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