Breakthrough in hydrogen fuel cells: Chemists develop way to safely store, extract hydrogen

 A team of USC scientists has developed a robust, efficient method of using hydrogen as a fuel source.

Hydrogen makes a great fuel because of it can easily be converted to electricity in a fuel cell and because it is carbon free. The downside of hydrogen is that, because it is a gas, it can only be stored in high pressure or cryogenic tanks.

In a vehicle with a tank full of hydrogen, "if you got into a wreck, you'd have a problem," said Travis Williams, assistant professor of chemistry at the USC Dornsife College.

A possible solution is to store hydrogen in a safe chemical form. Earlier this year, Williams and his team figured out a way to release hydrogen from an innocuous chemical material — a nitrogen-boron complex, ammonia borane — that can be stored as a stable solid.

Now the team has developed a catalyst system that releases enough hydrogen from its storage in ammonia borane to make it usable as a fuel source. Moreover, the system is air-stable and re-usable, unlike other systems for hydrogen storage on boron and metal hydrides.

The research was published this month in the Journal of the American Chemical Society.

"Ours is the first game in town for reusable, air stabile ammonia borane dehydrogenation," Williams said, adding that the USC Stevens Institute is in the process of patenting the system.

The system is sufficiently lightweight and efficient to have potential fuel applications ranging from motor-driven cycles to small aircraft, he said.

More information: A Robust, Air-Stable, Reusable Ruthenium Catalyst for Dehydrogenation of Ammonia Borane, J. Am. Chem. Soc., Article ASAP.
DOI: 10.1021/ja2058154

Abstract
We describe an efficient homogeneous ruthenium catalyst for the dehydrogenation of ammonia borane (AB). This catalyst liberates more than 2 equiv of H2 and up to 4.6 system wt % H2 from concentrated AB suspensions under air. Importantly, this catalyst is robust, delivering several cycles of dehydrogenation at high [AB] without loss of catalytic activity, even with exposure to air and water.

Provided by University of Southern California (news : web)

Breakthrough in hydrogen fuel cells: Chemists develop way to safely store, extract hydrogen

A team of USC scientists has developed a robust, efficient method of using hydrogen as a fuel source.

Hydrogen makes a great fuel because of it can easily be converted to electricity in a fuel cell and because it is carbon free. The downside of hydrogen is that, because it is a gas, it can only be stored in high pressure or cryogenic tanks.

In a vehicle with a tank full of hydrogen, "if you got into a wreck, you'd have a problem," said Travis Williams, assistant professor of chemistry at the USC Dornsife College.

A possible solution is to store hydrogen in a safe chemical form. Earlier this year, Williams and his team figured out a way to release hydrogen from an innocuous chemical material -- a nitrogen-boron complex, ammonia borane -- that can be stored as a stable solid.

Now the team has developed a catalyst system that releases enough hydrogen from its storage in ammonia borane to make it usable as a fuel source. Moreover, the system is air-stable and re-usable, unlike other systems for hydrogen storage on boron and metal hydrides.

The research was published this month in the Journal of the American Chemical Society.

"Ours is the first game in town for reusable, air stabile ammonia borane dehydrogenation," Williams said, adding that the USC Stevens Institute is in the process of patenting the system.

The system is sufficiently lightweight and efficient to have potential fuel applications ranging from motor-driven cycles to small aircraft, he said.

The research was funded by the Hydrocarbon Research Foundation and the National Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Southern California. The original article was written by Robert Perkins.

Journal Reference:

Brian L. Conley, Denver Guess, Travis J. Williams. A Robust, Air-Stable, Reusable Ruthenium Catalyst for Dehydrogenation of Ammonia Borane. Journal of the American Chemical Society, 2011; 110818113439060 DOI: 10.1021/ja2058154

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Poplar tree leaf bud extract could fight skin aging

Antioxidants are popular anti-aging ingredients in skin creams, and now scientists are reporting a new source of these healthful substances — leaf buds of poplar trees. Their study appears in the ACS' Journal of Agricultural and Food Chemistry.

Xavier Vitrac and colleagues note that there's a long history of using poplar buds to treat various health problems, such as colds, sinusitis, sunburn and arthritis. A substance found in beehives that is made from poplar buds (called propolis) also appears to have similar disease-fighting benefits. Propolis' effects seem to be due to poplar bud compounds, but very little is known about these substances. To see whether poplar buds are a good source of antioxidants for skin creams, the researchers decided to test an extract from the buds.

The group found that poplar bud extract had moderate antioxidant activity, and it demonstrated anti-aging effects on cells in the laboratory. "The collective antioxidant properties and transcriptional effect of this extract suggest potential anti-aging properties which could be utilized in cosmetic and nutraceutical formulations," the scientists say.

More information: “Phenolic Composition and Antioxidant Properties of Poplar Bud (Populus nigra) Extract: Individual Antioxidant Contribution of Phenolics and Transcriptional Effect on Skin Aging” J. Agric. Food Chem., 2011, 59 (9), pp 4527–4536 DOI: 10.1021/jf104791t

Abstract
The Populus species possess great potential for therapeutical applications, especially for their known anti-inflammatory properties. The antioxidant properties of propolis, a hive product collected by honey bees mainly from poplar bud exudates, suggest that poplar buds also possess antioxidant properties. Here is reported the characterization of the antioxidant properties of an aqueous poplar bud (Populus nigra) extract. It presented a high total phenolic content, and moderate antioxidant properties as determined by ORAC assay. The main phenolic compounds identified were phenolic acids and flavonoid aglycons. These phenolic compounds were analyzed by ORAC assay for their individual antioxidant activity, in order to determine the major contributors to the total antioxidant activity of the extract. Thanks to their high antioxidant activity, caffeic and p-coumaric acids were identified as the major antioxidant components. Representing only 3.5% of its dry weight, these compounds represented together about 50% of the total antioxidant activity of the extract. The antioxidant properties of poplar bud extract and the phenolic compounds identified were also analyzed by cellular antioxidant activity assay (CAA), which was weakly correlated with ORAC assay. The transcriptional effect of poplar bud extract on skin aging was evaluated in vitro on a replicative senescence model of normal human dermal fibroblasts, using a customized DNA macroarray specifically designed to investigate skin aging markers. Among the detected genes, poplar bud extract significantly regulated genes involved in antioxidant defenses, inflammatory response and cell renewal. The collective antioxidant properties and transcriptional effect of this extract suggest potential antiaging properties which could be utilized in cosmetic and nutraceutical formulations.

Provided by American Chemical Society (news : web)

A honey of a natural sunblock for UV-protective clothing: Honeysuckle extract

With those months of blazing summer sunshine head, scientists are reporting that an extract of the honeysuckle plant could make a highly-effective natural coating for clothing designed to protect people from exposure to potentially harmful ultraviolet (UV) rays from the sun. Their report appears in ACS' journal Industrial & Engineering Chemistry Research.

Ren-Cheng Tang and Sha-Sha Sun note the growing trend among consumers -- concerned about the risk of skin cancer and premature aging of the skin — toward relying on clothing for protection from the sun ultra-violet rays. Natural UV-protection coatings can have advantages, including production in a more sustainable fashion with less environmental impact. They note that honeysuckle has been used for centuries in traditional Chinese medicine to treat colds and fever. An ingredient in honeysuckle is used to preserve food and as additive in cosmetics to keep the skin looking younger. In their new study, the scientists wanted to see whether honeysuckle extract could boost wool's ability to block UV rays.

They found that wool coated with honeysuckle extract blocked UV rays much more effectively than untreated wool, giving the fabric a high UV protection factor. The extract was durable and remained active on wool, even after a long exposure to sunlight and laundering. The researchers conclude that honeysuckle extract shows significant potential as a natural UV-blocking agent for clothing.

More information: “Adsorption and UV Protection Properties of the Extract from Honeysuckle onto Wool”, Ind. Eng. Chem. Res., 2011, 50 (8), pp 4217–4224. DOI: 10.1021/ie101505q

Abstract
The adsorption and UV-protection properties of water-extract from honeysuckle whose main ingredient is chlorogenic acid onto wool were studied. The effect of initial pH on the adsorption was investigated, and the extent of adsorption was found to increase with decreasing pH in the range 2-7. Four kinetic equations, namely pseudo-first-order, pseudo-second-order, Elvoich, and intraparticle diffusion equations were employed to investigate the adsorption rates. The pseudo-second-order model provided the best fit to the experimental data and was indicated with the activation energy of 47.91 kJ mol-1. The equilibrium adsorption data were fitted by Freundlich, Langmuir, Redlich-Peterson, and Langmuir-Nernst isotherm models. The adsorption behavior accorded with Redlich-Peterson and Langmuir-Nernst models well. The honeysuckle extract showed good build-up properties, and the UV transmittance in the range of UVA and UVB of wool treated with honeysuckle extract decreased obviously while the ultraviolet protection factors increased. The extract of honeysuckle may be developed as a natural UV-absorbing agent applied to wool finishing.

Provided by American Chemical Society (news : web)

Fracking controversy: Using water, sand and chemicals to extract natural gas from shale

The turmoil in oil-producing nations is triggering turmoil at home, as rising oil prices force Americans to pay more at the pump. Meanwhile, there's a growing industry that's promising jobs and access to cheaper energy resources on American soil, but it's not without its controversy.

Deborah Kittner, a University of Cincinnati doctoral student in geography, presents, "What's the Fracking Problem? Extraction Industry's Neglect of the Locals in the Pennsylvania Marcellus Region," at the annual meeting of the Association of American Geographers. Kittner will be presenting April 14 at the meeting in Seattle. She is part of a large contingent of UC researchers to be presenting at the conference.

Hydraulic fracturing, or fracking, involves using millions of gallons of water, sand and a chemical cocktail to break up organic-rich shale to release natural gas resources. Kittner's research examined the industry in Pennsylvania, known as the "sweet spot" for this resource, because of the abundance of natural gas. Pittsburgh has now outlawed fracking in its city limits as has Buffalo, N.Y., amid concerns that chemical leaks could contaminate groundwater, wells and other water resources.

The EPA is now doing additional study on the relationship of hydraulic fracturing and drinking water and groundwater after congress stated its concern about the potential adverse impact that the process may have on water quality and public health. Kittner attended an EPA hearing and also interviewed people in the hydraulic fracturing industry. She says billions of dollars from domestic as well as international sources have been invested in the industry.

The chemical cocktail used in the process is actually relatively small. The mixture is about 95-percent water, nearly five percent sand, and the rest chemical, yet, Kittner says some of those chemicals are known toxins and carcinogens, hence, the "not in my backyard" backlash from communities that can be prospects for drilling. The flow-back water from drilling is naturally a very salty brine, prone to bacterial growth, and potentially contaminated with heavy metals, Kittner says. In addition, there's the question of how to properly dispose of millions of gallons of contaminated water, as well as concerns about trucking it on winding, rural back roads.

Based on her research, Kittner says that many in the industry are "working to be environmentally responsible, and become frustrated at companies that do otherwise."

"I think that the study that the EPA is doing is going to be really helpful, and the industry -- however reluctant to new regulations -- is working with the EPA on this," Kittner says.

Kittner has lived in Ft. Thomas, Ky., for two decades, but is originally from Warren, Pa. Her research took her to an EPA public meeting in Canonsburg, Pa., where she audio-taped 114 people presenting public statements of what they wanted the EPA study to examine. That study is expected to be completed in 2012 and will include an examination of what to do with millions of gallons of contaminated flow-back water.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Cincinnati.