A simple technique to make a common virus-killing material significantly more effective is a breakthrough from the Rice University labs of Andrew Barron and Qilin Li.
Rather than trying to turn the process into profit, the researchers have put it into the public domain. They hope wide adoption will save time, money and perhaps even lives.
The Rice professors and their team reported in Environmental Science and Technology, an American Chemical Society journal, that adding silicone to titanium dioxide, a common disinfectant, dramatically increases its ability to degrade aerosol- and water-borne viruses.
"We're taking a nanoparticle that everyone's been using for years and, with a very simple treatment, we've improved its performance by more than three times without any real cost," said Barron, Rice's Charles W. Duncan Jr.-Welch Professor of Chemistry and a professor of materials science. Barron described himself as a "serial entrepreneur," but saw the discovery's potential benefits to society as being far more important than any thoughts of commercialization.
Barron said titanium dioxide is used to kill viruses and bacteria and to decompose organics via photocatalysis (exposure to light, usually ultraviolet). The naturally occurring material is also used as a pigment in paints, in sunscreen and even as food coloring.
"If you're using titanium dioxide, just take it, treat it for a few minutes with silicone grease or silica or silicic acid, and you will increase its efficiency as a catalyst," he said.
Barron's lab uses "a pinch" of silicon dioxide to treat a commercial form of titanium dioxide called P25. "Basically, we're taking white paint pigment and functionalizing it with sand," he said.
Disinfecting a volume of water that once took an hour would now take minutes because of the material's enhanced catalytic punch, Barron said. "We chose the Yangtze River as our baseline for testing, because it's considered the most polluted river in the world, with the highest viral content," he said. "Even at that level of viral contamination, we're getting complete destruction of the viruses in water that matches the level of pollution in the Yangtze."
Using a smaller amount of treated P25 takes longer but works just as well, he said. "Either way, it's green and it's cheap."
The team started modifying titanium dioxide two years ago. Li, an assistant professor in civil and environmental engineering whose specialties include water and wastewater treatment, approached Barron to help search for new photocatalytic nanomaterials to disinfect drinking water.
The revelation came when students in Barron's lab heated titanium dioxide, but it wasn't quite the classic "aha!" moment. Graduate student and co-author Michael Liga saw the data showing greatly enhanced performance and asked fellow graduate student Huma Jafry what she had done. Jafry, the paper's first author, said, "I didn't do anything," Barron recalled.
When Barron questioned Jafry, who has since earned her doctorate, he discovered she used silicone grease to seal the vessel of P25 before heating it. Subsequent testing with nonsilicone grease revealed no change in P25's properties, whether the sample was heated or not. Remarkably, Barron said, further work with varying combinations of titanium dioxide and silicone dioxide found the balance between the two at the time of the discovery was nearly spot-on for maximum impact.
Barron said binding just the right amount of silica to P25 creates an effect at the molecular level called band bending. "Because the silicone-oxygen bond is very strong, you can think of it as a dielectric," he said. "If you put a dielectric next to a semiconductor, you bend the conduction and valence bands. And therefore, you shift the absorption of the ultraviolet (used to activate the catalyst)."
Bending the bands creates a path for electrons freed by the UV to go forth and react with water to create hydroxyl radicals, an oxidant responsible for contaminant degradation and the most significant reactive agent created by titanium dioxide. "If your conduction band bends to the degree that electrons find it easier to pop out and do something else, your process becomes more efficient," Barron said.
Li saw great potential for enhanced P25. In developed countries, photo reactors designed to take advantage of the new material in centralized treatment plants could more efficiently kill bacteria and inactivate viruses in water supplies while minimizing the formation of harmful disinfection byproducts, she said.
But the greatest impact may be in developing nations where water is typically disinfected through the SODIS method, in which water is exposed to sunlight for its heat and ultraviolet radiation.
"In places where they don't have treatment plants or even electricity, the SODIS method is great, but it takes a very long time to make water safe to drink," Li said. "Our goal is to incorporate this photocatalyst so that instead of taking six hours, it only takes 15 minutes."
Barron wants to spread the good news. "Here's a way of taking what is already a very good environmental catalyst and making it better," he said. "It works consistently, and we've done batch after batch after batch of it now. The methodology in the paper is the one we routinely use. As soon as we buy P25, we treat it."
The Robert A. Welch Foundation, the U.S. Navy and the National Science Foundation Center for Biological and Environmental Nanotechnology supported the research.
Read the abstract at http://pubs.acs.org/doi/abs/10.1021/es102749e
A high-resolution photo of the authors is available at http://www.media.rice.edu/images/media/NEWSRELS/TiO2team.jpg
CAPTION: From left, Professor Qilin Li, graduate student Michael Liga, alumna Huma Jafry and Professor Andrew Barron have published a paper outlining their method to dramatically improve the effectiveness of a common disinfectant. (Credit: Jeff Fitlow/Rice University)
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,279 undergraduates and 2,277 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of under 6-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.
David Ruth | EurekAlert!
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research