Capacitive deionization (CDI) technology, which uses carbon aerogels as the basis for its desalination processes, is one step closer to full commercialization as its government licensee seeks to finalize arrangements to begin volume production of CDI modules by mid-2004.

Capacitive Deionization Technology Systems, Inc. (CDT) licensed CDI and aerogel technology in 1997 from the Lawrence Livermore National Laboratory, which had originally developed aerogels to use as insulating agents in aerospace programs. CDT has spent the intervening years refining the manufacturing process to lower the cost of aerogel and optimizing CDI's desalination efficiency.

CDI technology uses almost weightless carbon aerogel - open-cell polymers with pores less than 50 nanometers in diameter that are created through a process known as sol-gel polymerization. Simple molecules called monomers are suspended in solution and react with one another to form a sol, or collection, of colloidal clusters. The macromolecules become bonded and cross-linked, forming a nearly solid, transparent sol-gel. An aerogel is produced by carefully drying the sol-gel so that the fragile network does not collapse. The complicated, cross-linked internal structure gives aerogels the highest internal surface area per gram of material of any known material.

In the CDI desalination process, solution is passed between aerogel sheets in which electrodes have been embedded. Ions such as sodium and chloride are removed from the flow by becoming attracted to the positive or negatively charged aerogel sheets and held in an electric field on the surface of the aerogel. After a suitable period of time, the electrical current is reversed and the ions rinsed off into a concentrate stream.

CDT says one AquaCell module can remove 1,000 ppm of suspended solids from about 3,800 liters of water daily. Company officials say the methodology is "scaleable," simply putting more modules in parallel to raise the volume or placing modules in parallel to raise the volume or placing modules in series to raise the purity. CDT says the design does not require pre-treating the water, and that the modules take no more power than a 100-watt light bulb.

CDT says it will initially target applications treating brackish water with solids concentrations of 8,000 ppm or less; by contrast, seawater has salt levels of about 32,000 ppm. The company says these applications include brackish aquifers as well as the water produced by coal bed methane extraction or other petroleum operations.

The company estimates that water at around 3,000 ppm salt concentrations can be treated at an operating cost of 9 cents per thousand liters - half or less of the cost of current reverse osmosis plants handling similar jobs.

CDT says it expects to sell its modules in the range of $1,200 to $1,500, which Livermore officials note is only about 2% of the manufacturing cost when the company acquired the technology from the lab.

The technology can be used for water purification applications, including brackish water desalination, pure water for power plant and boiler water polishing, ultra pure water for electronic, medical and food productions, and ground water remediation for industrial and agriculture requirements. CDI can be used also in the removal of nuclear elements.

CONTACT: Dallas Talley, Capacitive Deionization Technology Systems, Inc., 13636 Neutron Road, Dallas, TX 75244; 972-934-1586, Fax 972-934-1592.