New spheres trick trap and terminate water contaminant

center_img AddThis Rice University researchers have enhanced micron-sized titanium dioxide particles to trap and destroy BPA, a water contaminant with health implications. Cyclodextrin molecules on the surface trap BPA, which is then degraded by reactive oxygen species (ROS) produced by the light-activated particles. (Credit: Danning Zhang/Rice University) Rice University graduate student Danning Zhang, who led the development of a particle that attracts and degrades contaminants in water, checks a sample in a Rice environmental lab. (Credit: Jeff Fitlow/Rice University) http://news.rice.edu/files/2018/10/1008_WATER-2-WEB-uv6qff.jpg“Petals” of a titanium dioxide sphere enhanced with cyclodextrin as seen under a scanning electron microscope. When triggered by ultraviolet light, the spheres created at Rice University are effective at removing bisphenol A contaminants from water. (Credit: Alvarez Lab/Rice University) http://news.rice.edu/files/2018/10/1008_WATER-3-WEB-qtgfbg.jpgTitanium dioxide spheres enhanced with cyclodextrin created at Rice University are effective at removing bisphenol A from water. The micron-scale spheres are large enough to be easily removed from treated water for reuse. (Credit: Alvarez Lab/Rice University) Return to article. Long Description Return to article. Long DescriptionRice University researchers have enhanced micron-sized titanium dioxide particles to trap and destroy BPA, a water contaminant with health implications. Cyclodextrin molecules on the surface trap BPA, which is then degraded by reactive oxygen species (ROS) produced by the light-activated particles. Illustration by Danning ZhangMicron-sized spheres created in the lab of Rice environmental engineer Pedro Alvarez are built to catch and destroy bisphenol A (BPA), a synthetic chemical used to make plastics.The research is detailed in the American Chemical Society journal Environmental Science & Technology.BPA is commonly used to coat the insides of food cans, bottle tops and water supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.The good news is that reactive oxygen species (ROS) – in this case, hydroxyl radicals – are bad news for BPA. Inexpensive titanium dioxide releases ROS when triggered by ultraviolet light. But because oxidating molecules fade quickly, BPA has to be close enough to attack.That’s where the trap comes in.Close up, the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Rice researchers to anchor cyclodextrin molecules.Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. BPA is also hydrophobic and naturally attracted to the cavity. Once trapped, ROS produced by the spheres degrades BPA into harmless chemicals.In the lab, the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.last_img