A golden opportunity to detect, clean mercury-polluted waters

Diagram of the process

ORLANDO, July 29, 2005 -- Two University of Central Florida scientists have developed a new way to find and remove mercury from mercury-polluted water. Using tiny pieces of gold and the properties of light, chemistry professors Florencio E. Hernández and Andres Campiglia can now quickly and inexpensively detect even trace amounts of the pollutant. In the near future, this process can be used to create water filters and reclaim contaminated water.

Florida's soil and water contain some of the highest levels of mercury in the world, especially in the Everglades. Mercury pollution often comes from coal-burning power plants, waste incinerators and certain manufacturing processes. The mercury from these industries is absorbed into the atmosphere where precipitation deposits it in streams, lakes, and oceans. Once in the water, bacteria change the mercury into methylmercury, which is absorbed by fish and transferred to animals that eat the fish -- like birds, bears, or humans.

The first step to cleaning polluted water is detecting it. Hernández and Campiglia's mercury detection method uses gold nanoparticles, each about 2,000 times smaller than the width of a human hair. First, a liquid solution containing gold nanoparticles is mixed with a sample of the possibly-contaminated water. Then, because mercury has such a strong affinity for gold, any mercury in the water quickly binds with the gold.

Next, the scientists use a small portable device, called an optical spectrometer, to monitor the way the gold absorbs light. By observing the changes in the light, they can determine how much mercury the gold absorbed and, consequently, how much mercury was present in the water. The process takes less than ten minutes and is highly accurate. Even very small amounts of mercury can be detected.

Hernández and Campligia are currently applying these techniques to the removal of mercury from water systems. The same technology used to create the gold nanoparticles for detection can also be used to produce water filters on both large and small scales. These filters could be fitted in drainage systems that lead to major waterways, in residential sinks, and at power plants.

According to the EPA, mercury-pollution presents a serious health hazard to humans. Although most people have small, safe amounts of mercury in their bodies, large amounts of it can cause injury to the brain, kidneys, heart, lungs, or immune system. Mercury is especially damaging to unborn children, who can develop permanent mental problems from exposure to mercury while in the womb.

Currently, it is difficult to detect mercury in contaminated water. The detection equipment is bulky and it cannot detect small amounts of the pollutant. Hernández and Campiglia expect to continue refining their mercury-pollution efforts with support from the State of Florida and the U.S. Environmental Protection Agency.

For more information on Hernández and Campiglia, go to the UCF Chemistry Department website at www.cas.ucf.edu/chemistry. To learn more about mercury pollution, its impact on people and the environment, and ways to protect yourself from it, go to the EPA's mercury website: www.epa.gov/mercury.

For More Information
     Florencio Eloy Hernández, Andres D. Campiglia
     Department of Chemistry, CH 117
     University of Central Florida
     Orlando, FL 32816