Skip to main content

Building a better salt trap: Scientists synthesize a molecular 'cage' to trap chloride !!

Indiana University researchers have created a powerful new molecule for the extraction of salt from liquid. The work has potential to help increase the amount of drinkable water on Earth.

Built using chemical bonds previously regarded as too weak, the new molecule is about ten billion times improved compared to a similar structure created over 10 years ago at IU. The molecules' design was reported May 23 in the journal Science.
"If you were to place one-millionth of a gram of this molecule in a metric ton of water, 100 percent of them will still be able to capture a salt," said Yun Liu, who led the study as a Ph.D. student in the lab of Amar Flood, the James F. Jackson Professor of Chemistry and Luther Dana Waterman Professor in the IU Bloomington College of Arts and Sciences' Department of Chemistry.
The molecule is designed to capture chloride, which is formed when the element chlorine pairs with another element to gain an electron. The most familiar chloride salt is sodium chloride, or common table salt. Other chloride salts are potassium chloride, calcium chloride and ammonium chloride.
At the same time that the human population continues to grow, the seepage of salt into fresh water systems is reducing access to drinkable water across the globe. In the U.S. alone, the U.S. Geological Survey estimates 271 metric tons of dissolved solids, including salts, enter freshwater streams per year. Contributing factors include the chemical processes involved in oil extraction, the use of road salts and water softeners, and the natural weathering of rock. It only takes one teaspoon of salt to permanently pollute five gallons of water.
The new salt-extraction molecule created at IU is comprised of six triazole "motifs" -- five-membered rings comprised of nitrogen, carbon and hydrogen -- which together form a three-dimensional "cage" perfectly shaped to trap chloride. In 2008, Flood's lab created a two-dimensional molecule, shaped like a flat donut, which used four triazoles. The two extra triazoles give the new molecule its three-dimensional shape, and ten billion-fold boost in efficacy.
The molecule is also unique because it binds chloride using carbon-hydrogen bonds, previously regarded as too weak to create stable interactions with chloride compared to the traditional use of nitrogen-hydrogen bonds. Despite expectations, the researchers found the use of triazoles created a cage so rigid as to form a vacuum in the center, which draws in chloride ions.
By contrast, cages with nitrogen-hydrogen bonds are often more flexible -- and the vacuum-like center needed for chloride capture requires energy input, lowering their efficiency compared to a triazole-based cage.
"If you were to take our molecule and stack it up against other cages that use [stronger] bonds, we're talking many of orders of magnitude of performance increase," said Flood. "This study really shows that rigidity is underappreciated in the design of molecular cages."
The rigidity also enables the molecule to retain its shape after the central chloride has been lost, compared to other designs that collapse under the same circumstances due to their flexibility. This provides the molecule greater efficacy and versatility.
The work is also reproducible. The first molecule took nearly a year to synthesize, said Liu, who was shocked to discover the crystals required to confirm the molecule's unique structure formed after the experiment was left alone in the lab for several months -- a surprising occurrence since this process typically requires careful monitoring.
The formation of the crystal represented a "eureka" moment, proving the molecule's unique design was actually viable. Later, Wei Zhao, a postdoctoral researcher in Flood's lab, was able to re-create the molecule in several months.
The final author on the study is Chun-Hsing "Josh" Chen, an associate scientist at the IU Molecular Structure Center at the at the time of the study, who confirmed the molecule's structure using x-ray crystallography.
Liu is currently a postdoctoral research associate at the University of Illinois-Urbana Champaign. This work was supported in part by the U.S. Department of Energy. A patent on the work has been filed by IU's Innovation and Commercialization Office.
Article Source:
Materials provided by Indiana University
Note: Content may be edited

Comments

Post a Comment

Popular posts from this blog

Dark matter may be older than the Big Bang

Dark matter, which researchers believe make up about 80% of the universe's mass, is one of the most elusive mysteries in modern physics. What exactly it is and how it came to be is a mystery, but a new Johns Hopkins University study now suggests that dark matter may have existed before the Big Bang. The study, published August 7 in  Physical Review Letters , presents a new idea of how dark matter was born and how to identify it with astronomical observations. "The study revealed a new connection between particle physics and astronomy. If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way. This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too," says Tommi Tenkanen, a postdoctoral fellow in Physics and Astronomy at the Johns Hopkins University and the study's author. While not much is known about its origins,...
Post a Comment
Read more

Home births as safe as hospital births: International study suggests

A large international study led by McMaster University shows that low risk pregnant women who intend to give birth at home have no increased chance of the baby's perinatal or neonatal death compared to other low risk women who intend to give birth in a hospital. The results have been published by  The Lancet 's  EClinicalMedicine  journal. "More women in well-resourced countries are choosing birth at home, but concerns have persisted about their safety," said Eileen Hutton, professor emeritus of obstetrics and gynecology at McMaster, founding director of the McMaster Midwifery Research Centre and first author of the paper. "This research clearly demonstrates the risk is no different when the birth is intended to be at home or in hospital." The study examined the safety of place of birth by reporting on the risk of death at the time of birth or within the first four weeks, and found no clinically important or statistically different risk between home...
Post a Comment
Read more

GSAT-11 satellite to be launched from French Guiana on Dec 5th

GSAT-11 satellite to be launched from French Guiana on Dec 5th GSAT-11 would be located at 74 East and is the fore-runner in a series of advanced communications satellite with multi-spot beam antenna coverage over Indian mainland and Islands, ISRO said. GSAT-11 is the next generation “high throughput” communication satellite configured around ISRO’s I-6K Bus. (PTI/Representational). Indian space agency ISRO is scheduled to launch GSAT-11, the “heaviest” satellite built by it, on-board Ariane-5 rocket of Arianespace from French Guiana on December 5. Weighing about 5,854 kg, GSAT-11 would play a vital role in providing broadband services across the country, and also provide a platform to demonstrate new generation applications, the Indian Space Research Organisation (ISRO) said. It is the “heaviest” satellite built by ISRO, the space agency said. GSAT-11 is the next generation “high throughput” communication satellite configured around ISRO’s  I-6K Bus, and it...
Post a Comment
Read more