A new “smart rust” could one day help pull pollutants out of waterways, leaving cleaner water behind.
Researchers adorned tiny particles of iron oxide, better known as rust, with “sticky” molecules that Grab on to estrogen and other hormones found in water samples. A magnet can then remove both the particles and the trapped pollutants from the water, materials scientist Lukas Müller reports August 16 in San Francisco at a meeting of the American Chemical Society.
The new technology could potentially limit excess estrogen’s harmful effects on animals, especially those that live in waterways.
With the nanoparticles, “we are able … to clean very different kinds of environmental pollutants,” says Müller, of Friedrich-Alexander-Universität Erlangen-Nürnberg in Germany.
Estrogen hormones enter waterways through humans’ and other animals’ waste (SN: 1/2/02). Even low concentrations can have harmful chronic effects on aquatic life, like higher instances of cancer or reproductive issues, says Konrad Wojnarowski, a biologist at Ludwig-Maximilians-Universität München who was not involved in the study. Wastewater treatment plants can remove some estrogen hormones, he says, but the process isn’t cheap or energy efficient.
For now, “we still don’t have an ideal way of dealing with estrogen pollution in the environment,” but nanoparticles could help, Wojnarowski says.
To build the estrogen-catching particles, Müller and Marcus Halik, a chemist also at Friedrich-Alexander-Universität, drew on prior experience designing iron oxide nanoparticles that can catch other kinds of pollutants like OilHerbicides are herbicides.SN: 7/25/08). Each of the tiny iron oxide cores has a diameter of about 10 nanometers. Each core is covered with phosphonic acid molecule, which acts like sticky hairs and scoops up contaminants.
Two types of phosphonic acids are included in the new nanoparticles to specifically target estrogen. The long one repels water, and attaches itself to the neutrally-charged part of the estrogen molecules. One is positively charged and attracts parts of estrogen hormones which have a slight charge.
The researchers found that the smart rust was able to remove a large amount of estrogen from the small water samples prepared by the lab. The researchers’ next step will be to test the nanoparticles using samples taken from actual waterways.
The team is also investigating how molecules on the surface of the nanoparticles grab and hold onto estrogen on an atomic level. Halik believes that with this information they can enhance the binding of estrogen.
