Estrogen can harm aquatic plants and animals when passed into waterways via human and agricultural waste streams. Researchers have now developed a new way of removing the hormone from water, however, using what's known as "smart rust."
Developed by scientists at Germany's University of Erlangen-Nuremberg, smart rust takes the form of spherical iron oxide (aka rust) nanoparticles that are covered in phosphonic acid molecules. The molecules protrude from the surface of the spheres like hairs. By binding different compounds to the ends of those hairs, it's possible to make them adsorb different types of waterborne pollutants.
The iron oxide particles themselves are superparamagnetic, meaning they're attracted to magnets but not to one another. This quality keeps them from clumping together – so they can be thoroughly mixed into tainted water – while also making it possible to subsequently remove them from that water simply by swirling a magnet through the liquid.
As the smart rust nanoparticles are taken out of the water, they take the adsorbed pollutants with them. It's even possible to later release the pollutants from the particles so the former can be safely disposed of, and the latter can be reused.
In previous lab tests, smart rust had been used to remove crude oil, microplastic particles and the herbicide glyphosate from water samples. More recently, Erlangen-Nuremberg graduate student Lukas Müller wondered if the technology could also be utilized to remove natural and synthetic estrogen.
Due to the fact that estrogen molecules consist of a large steroid body with a slight negative charge, he coated smart rust particles with two types of molecules. One of these has particularly long "hairs," while the other is positively charged. When combined on the surface of the iron oxide spheres, these molecules form multitudes of estrogen-trapping pockets.
When tested on water spiked with estradiol, which is the most potent type of estrogen, the new form of smart rust successfully removed the hormone from that water. Further research will now explore how well the technology works in real-world conditions, and how many times the particles can be reused.
The complete findings of the study, which was led by Dr. Marcus Halik, are being presented this week at the fall meeting of the American Chemical Society.
Source: American Chemical Society via EurekAlert