Researchers Use Gold to Detect, Clean Mercury-Polluted Water

Tiny pieces of gold and the properties of light can help scientists find and remove mercury from polluted water, two University of Central Florida chemistry professors have found.

Professors Florencio E. Hernández and Andres Campiglia can quickly and inexpensively detect even trace amounts of mercury in less than 10 minutes by mixing small amounts of gold with water. The gold absorbs the mercury while the researchers monitor changes in the amount of light through a hand-held device called an optical spectrometer. This process can be used to create water filters and reclaim contaminated water.

Florida’s soil and water, especially in the Everglades, contain some of the highest levels of mercury in the world. 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 people or animals that eat the fish.

The first step to cleaning polluted water is detecting it. Hernández and Campiglia’s mercury detection method uses gold nanoparticles, each of which is 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. Because mercury has such a strong affinity for gold, any mercury in the water quickly binds with the gold.

Next, the scientists use the portable 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 10 minutes and is highly accurate. Even small amounts of mercury can be detected.

Hernández and Campiglia are 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 Environmental Protection Agency, mercury pollution presents a serious health hazard to humans. Although most people have small, safe amounts of mercury in their bodies, large amounts 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.

It is difficult to detect mercury in contaminated water. Commonly used detection equipment is bulky, and it cannot detect small amounts of the pollutant. Hernández and Campiglia hope to obtain support from the state of Florida and the Environmental Protection Agency as they continue to refine their approach to detecting mercury.

For more information on Hernández and Campiglia, go to http://chemistry.cos.ucf.edu . To learn more about mercury pollution and its impact on people and the environment, go to http://www.epa.gov/mercury.