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Josie Giles, School of Chemical & Biomolecular Engineering
Contact Josie Giles josie.giles@chbe.gatech.edu
404-385-2299
Researchers Address Practical Solutions to Water and Gas Crises
Atlanta (July 16, 2008) — Dr. William Koros recently gave an interview to Atlanta television station WXIA reporter Marc Pickard. What was the topic? Precisely what is on every Georgian’s mind right now: the continuing drought and what to do about the state’s water resources. Dr. Koros’ research involves the complicated science of membrane-based gas separation and selected liquid separation topics. As an expert on using high-tech membranes to filter impurities from water, Dr. Koros commented on the feasibility of Georgia employing desalination of ocean water to help solve its water-shortage crisis.
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“Desalination is really just a super-fine filtration that’s actually able to pull even ions out of the water, and ions are incredibly small entities,” Dr. Koros says. However, although desalination is a relatively simple process that has been used since the end of World War II, he does not believe that it is an economically realistic option for Georgia.
Dr. Koros explains that for every 100 gallons of untreated ocean water that come into the filter, 60 gallons come out and return to the ocean, but the remaining 40 gallons come out as purified fresh water. It takes ten times the energy to desalinate ocean water than to purify ground or surface water, and because Atlanta is landlocked, piping it into the city would be an expensive operation. Atlanta is approximately 250 miles from the shores of Savannah, Ga. and almost 300 miles from Panama City, Fla. Although it is reasonable to understand why desalination is a viable solution for coastal cities like Tampa, Fla., which provides 10% of the city’s 2.4 million inhabitants with fresh water, Dr. Koros says that “I think the wisest thing is not to try to run off and spend a lot of money doing that but rather to figure out how to do things more efficiently.”
Although membranes can be used for water purification, Dr. Koros is currently using water to help solve another crisis on the minds of Georgians, the rising cost of gas. Dr. Koros, along with Dr. Sankar Nair and a team of researchers, is working on two separation projects aimed at improving the energy efficiency of the biofuel process so as to eliminate the expensive and energy-intensive distillation process. A membrane-based approach minimizes the need to supply heat energy, and instead relies on differences in the transport rates of the components through a membrane to achieve separation. The challenge is in producing selective membrane systems that can produce pure ethanol.
Currently, Drs. Koros and Nair are exploring membranes that contain nanoparticles of porous inorganic materials called zeolites that are so small they can be dispersed efficiently into a polymer matrix. The very specific porosity of the zeolite should allow separation of ethanol from water. By using two membranes in series—the first hydrophobic to remove ethanol from a large mass of water and the second hydrophilic to remove any trace water in the ethanol product from the first membrane—it may be possible to design an economical membrane process for biofuel separation from water.
Related Links
Dr. William Koros
http://www.chbe.gatech.edu/fac_staff/faculty/koros.php
Dr. Sankar Nair
http://www.chbe.gatech.edu/fac_staff/faculty/nair.php
School of Chemical & Biomolecular Engineering
http://www.chbe.gatech.edu
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