Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




DISASTER MANAGEMENT
'Ship in a bottle' detects dangerous vapors
by Staff Writers
Houston TX (SPX) Oct 15, 2013


A rhenium-based complex trapped inside zeolite is able to warn of the presence of dangerous fumes from solvents. The Rice University researchers used a "ship-in-a-bottle" type of chemical assembly to create the promising material. Courtesy of the Marti Lab.

Rice University scientists took a lesson from craftsmen of old to assemble microscopic compounds that warn of the presence of dangerous fumes from solvents. The researchers combined a common mineral, zeolite, with a metallic compound based on rhenium to make an "artificial nose" that can sniff out solvent gases.

They found that in the presence of the compound, each gas had a photoluminescent "fingerprint" with a specific intensity, lifetime and color. Rice chemist Angel Marti and his students reported their results this month in the journal Angewandte Chemie.

The challenge for Marti and his team was to get their large metallic particles through the much smaller pores of a zeolite cage. The answer: Do it old-school. In their process, small chemical components enter the cage, find each other and self-assemble into rhenium complexes. Then they're stuck -- like a ship in a bottle.

"We sequentially load the individual parts of the complex into the zeolite," Marti said. "The parts are smaller than the pores, but when they self-assemble inside the zeolite, they're trapped." Once washed to eliminate complexes that form outside the zeolites, the compound is ready for use.

The relatively simple technique, which was initially developed and studied by two Rice alumni while they were undergraduate students in Marti's lab, could provide a scalable, inexpensive platform to monitor toxic vapors from industrial solvents.

Solvents are liquid chemicals, often petroleum-based, that are widely used to dissolve solid materials. They are found in paints, thinners, aerosol sprays, dyes, marking pens, adhesives and many other products.

They also evaporate quickly. Solvent vapors, which are hazardous to inhale and can be highly flammable, are often denser than air and gather at floor level, where they can build to dangerous amounts unless detected.

Marti said platinum, gold, palladium and copper salts are often used to detect vapors, because they change color in the presence of solvents. The rhenium-based supramolecular complex was known to fluoresce in the presence of some solvents, but dealing with vapors is a different story.

"If the complexes are in a solid state, they are too close to each other and gases can't interact with them," he said. "So we started thinking of ways to create space between them."

Enter zeolites. "These zeolites are cages with big cavities and small pores," Marti said. "The pores are big enough -- at about 7.4 angstroms -- for most gas-phase molecules to enter. The question was how to trap the bigger rhenium complexes inside."

Other groups have trapped ruthenium complexes in zeolites, but these complexes were not ideal to detect solvents. Then-undergraduates Ty Hanna and, later, Zack Panos developed the method to put rhenium complexes inside zeolites. The results were outstanding, Marti said.

Like canaries in a coalmine, the caged complexes strongly signal the presence of a vapor by the color and intensity of their photoluminescent glow in ultraviolet light.

Marti said nobody had studied the third key property -- the amount of time the complex remains in an excited state. That ranges from less than 1,000 nanoseconds for water and ammonia to "a quite long" 4,000-plus nanoseconds for pyridine. It's different for every type of vapor, he said.

"We concluded that every individual vapor has a set of photophysical properties that is unique for that solvent," he said. "Each one has a unique fingerprint."

With the ability to detect three distinct characteristics for each vapor, a team led by graduate student Avishek Saha built a three-dimensional plot to map the fingerprints of 17 types of solvents. They found categories of solvents -- nonpolar, alcohols, protics (which include water) and aprotics -- tended to gather in their own areas.

"That's another interesting thing," Marti said. "Different solvent groups occupy different areas in the map. So even if a solvent hasn't been studied, our material will help people recognize the category it falls into."

He said the group plans to test more solvents and suggested the material may also be useful for detecting the presence of other volatile species like explosives.

Rice graduate students Kewei Huang and Mayra Hernandez-Rivera are co-authors of the paper. Marti is an assistant professor of chemistry and bioengineering at Rice. Read the abstract here.

.


Related Links
Rice University
Marti Group
Bringing Order To A World Of Disasters
A world of storm and tempest
When the Earth Quakes






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





DISASTER MANAGEMENT
India, US trying to hamper Pakistan quake relief: top militant
Islamabad (AFP) Oct 14, 2013
The founder of a militant Islamist group blamed for the 2008 Mumbai attacks Monday accused the US and India of trying to hamper efforts to help victims of Pakistan's earthquake. Hafiz Mohammad Saeed, who has a $10 million US government bounty on his head, said joint US-Indian efforts to block funds for his Jamat-ud-Dawa (JuD) organisation were aimed at stopping its relief work in Baluchistan ... read more


DISASTER MANAGEMENT
'Ship in a bottle' detects dangerous vapors

Satellite flood maps reach crisis teams via Internet

US banks $584 mln in Egypt aid for safe-keeping

China launches satellite to monitor natural disaster

DISASTER MANAGEMENT
A thermoelectric materials emulator

Lockheed Martin and Concord Blue to Deploy Advanced Gasification Technology Globally

Lockheed Martin Powers on First GOES-R Weather Satellite

How to make ceramics that bend without breaking

DISASTER MANAGEMENT
Scientists warn of 'deadly trio' risk to ailing oceans

Dams provide resilience to Columbia from climate change impacts

South Atlantic fish resources at risk from warmer climate

Pacific's Palau mulls drone patrols to monitor waters

DISASTER MANAGEMENT
Russia to charge Greenpeace activists with piracy: report

Largest ice mass in California's Yosemite park melting, disappearing

Europe's top court rejects Inuit appeal against seal fur ban

Traces of immense prehistoric ice sheets: the climate history of the Arctic Ocean needs to be rewritten

DISASTER MANAGEMENT
Understanding soil nitrogen management using synchrotron technology

Protecting the weedy and wild kin of globally important crops

Hotpots and snake blood: Asia's libido-boosting foods

Farmers need help to plow through new food safety regulations

DISASTER MANAGEMENT
Crystals point to 'recycled' super-volcanic magma chambers

Scientists tag Indonesian volcano as source of 13th century eruption

Pakistan quake death toll rises to 376

Disaster officials warn New Orleans, Gulf coast over storm Karen

DISASTER MANAGEMENT
Nigeria bombs Boko Haram 'camp' near site of massacre

Canada reinforces African Union forces in Somalia

Disgruntled Malian troops fire weapons, kidnap officer

Ugandan officers court-martialed over alleged coup plot

DISASTER MANAGEMENT
Ancient sagas show Vikings more social, less warlike

Einstein's genius put down to 'well-connected' brain halves

Roma families face wholesale expulsion from France

Genetic study pushes back timeline for first significant human population expansion




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement