Tag Archives: nanotechnology

Shorter fibers: key to safer carbon nanotubes?

Synopsis by Marty Mulvihill Feb 05, 2013

Ali-Boucetta, H, A Nunes, R Sainz, MA Herrero, B Tian, M Prato, A Bianco and K Kostarelos, 2013. Asbestos-like pathogenicity of long carbon nanotubes alleviated by chemical functionalization, Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.201207664.

A shorter carbon nanotube may be a safer one, according to a group of European researchers who varied the materials’ structural fibers and tested their health effects in mice.

Carbon nanotubes are one of the most common and exciting examples of nanotechnology with potential uses in electronics and medicine, but they are made of fibers that resemble asbestos. The modified nanotubes with shorter fibers were less irritating to the mouse lung and showed no signs of cancer when compared to traditional carbon nanotubes.

This work demonstrates the importance of researchers from different disciplines teaming up to solve problems. When applied to green chemistry, toxicologists and chemists working together can create safer materials to help avoid unintended health and environmental consequences of new chemicals.

Many scientists predict that carbon nanotubes will have many useful applications. The nanomaterials could boost performance of our electronic devices, deliver drugs directly to cells and even enable more affordable space travel through lighter materials.

At the same time, other scientists and health experts worry that carbon nanotubes could create health problems in people. In particular, the fibrous structure of these tubes closely resembles the potent carcinogen asbestos. In fact, lab and animal studies have shown that carbon nanotubes do irritate lung tissue in the same way and lead to lung cancer in exposed animals.

Asbestos has been used in building materials, auto parts and coatings as an insulator and fire retardant. Asbestos fibers are released when products containing asbestos age or are disturbed in remodeling or replacement. When breathed in, the fibers can irritate lung tissue, causing cancer and other lung disease.

Now, a group of scientists report that they can make carbon nanotubes – picture sheets of carbon rolled into a cylinder – that are much safer and have fewer asbestos-like health effects.

By chemically modifying the surface of the very small carbon nanotubes, the researchers created fibers that are 10 times shorter than typical nanotube fibers. They tested these new materials head-to-head in mice with both untreated nanotubes and asbestos fibers.

They found that the chemical treatment produces fibers that caused much less irritation in the mouse lungs and did not show signs of cancer development during the seven days after injecting the nanotubes into the lungs.

More work and further testing are needed to understand the long-term impact of the modified nanotubes, including more details about biological interactions with the new nanomaterials.

 

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Silver from nanoparticles found in plants and animals.

Synopsis by Marty Mulvihill and Wendy Hessler

2012-0613mesocosm
Benjamin Espinasse, CEINT, Duke University
Mesocosms provided outdoor labs to study silver nanoparticles.

The silver from tiny particles used to kill microbes in clothing and other consumer goods may wind up in plants, insects and fish, according to new research. The study is the first to track how silver nanoparticles react, change and move through ecosystems, and it adds to a growing number of studies that raise concerns about their widespread use as anti-microbial agents. Researchers have not yet studied their potential effect on plants and animals.

 

Context

Manufacturers are putting silver nanoparticles into a growing list of consumer products despite the fact that little is known about their health or environmental impacts. The Project on Emerging Nanotechnologies estimates that as of 2010, more than 300 products use sliver nanoparticles as an antimicrobial agent. These items include clothing, food storage containers, pharmaceuticals, cosmetics, electronics and optical devices.Silver nanoparticles are very small chunks of silver metal made up of thousands of silver atoms. They are so small that 400 million would fit in the period at the end of this sentence. A chemical coat is often added to prevent clumping and protect their silver core.The element silver discourages the growth of bacteria and other pathogens. The U.S. Environmental Protection Agency regulates silver and some related compounds as pesticides. The agency supports health and safety testing of the highly used silver nanoparticles but does not regulate their specific use.Like most nanoparticles, silver varieties have benefits and risks. Their unique size gives them properties different from both large pieces of silver and individual silver ions. As antibacterial agents, the silver nanoparticles are far more effective, cheaper and use less silver than many alternatives.Silver’s ability to kill bacteria has raised concerns that the nanomaterials may affect beneficial bacteria and the plants and animals essential to a healthy ecosystem. While it is not considered toxic to people, invertebrates and fish are far more sensitive to silver.Cell studies suggest silver affects nerve cells, while silver nanoparticles have been shown to interfere with human sperm development. It is known that fish are vulnerable to even low doses of silver, andstudies indicate that silver nanoparticles can cause malformations and death in embryos exposed to the materials (Bar-Ilan et al. 2009). Exposure to silver also affects reproduction in clams (Brown et al. 2003).Silver nanoparticles are released from products during normal use and washing. They enter the environment through wastewater, as water treatment facilities do not always remove them completely (Keagi et al. 2011).Researchers are rushing to understand what happens to nanoparticles after they are released. Initial studies suggest they can clump together to make larger particles, dissolve to release silver ions and react with oxygen and sulfur to form new types of particles.

 

 

What did they do?

Silver nanoparticles were sprayed onto soil and water in simulated terrestrial and wetland habitats to determine how the particles might change chemically, move through the ecosystems and interact with plants and animals after they get into the environment.The researchers built the habitats (called mesocosms) in open boxes and left them outside in Duke Forest – a Duke University research area in North Carolina – for 18 months. They added wetland plants typical to the southern United States. Mosquitofish and insects were accidentally introduced with the plants and soils. Other wild insects colonized the ecosystems. Many of the species completed their life cycles during the project.They regularly sampled the soil, water and fish to follow how the silver moved through the constructed environment. At the end, silver levels were analyzed in the soil, water, plants and animals – the fish, fish embryos and insects. They also measured distinct silver compounds to determine how the silver ions reacted with oxygen, sulfur and chlorine in the soils and water.Silver levels measured in the dosed plots were compared to the levels measured in the control plots where silver nanoparticles had not been applied.

 

 

What did they find?

Researchers found silver accumulated in both the terrestrial plants (up to 3 percent of the total added) and the aquatic animals.Plants growing in soil that had been dosed with nanoparticles had up to 18 parts per million silver while lower silver levels – ranging from 1 – 7 parts per million – were measured in the plants growing near the water that was dosed with the silver nanoparticles. In all cases, silver was measured in plants that started growing 6 months or more after the application of silver nanoparticles, indicating that the plants could absorb the silver from the soil.They also measured levels of silver in the fish and insects, which included mosquitofish, dragonfly larvae and midges. The mosquitofish had 20 – 30 times higher silver levels than fish in the control plots.More troubling were the high levels (10 – 20 times higher than control) of silver that passed from female mosquitofish to their developing embryos. However, the majority of the silver – about 70 percent of the total put into the systems – was recovered from the soils and the wetland sediments. In addition, for silver nanoparticles applied to the terrestrial environment, erosion and runoff carried some of the metal from the soils into the water where it mostly settled in the sediments.The silver nanoparticles reacted and changed after they were released, but differed between the terrestrial and water habitats. By the end of the study only 18 percent of the silver that was added to the water remained in the original form. The majority – 55 percent – had reacted with sulfur to form silver sulfide, while about 27 percent bound to the organic matter in the bottom sediment.Particles applied to the terrestrial environment were slightly less reactive. Forty-seven percent remained in the original form, while 52 percent reacted to form silver sulfide. These reactions happened more slowly than predicted by laboratory experiments, showing that lab studies do not always accurately predict what happens in the environment.

 

What does it mean?

In terrestrial soil and water, silver nanoparticles can chemically change and contaminate plants and animals with silver. Any health effects from exposures to the metal in this way are not known.The outdoor study from North Carolina is one of the first long term ones to examine how silver nanoparticles change in the environment, specifically in soils, sediments and water. It is also a first step to clarifying where the silver nanoparticles move to after they enter the environment. One surprise was that they tend to settle in the soil and in the sediments underwater.The researchers demonstrated that under realistic conditions the majority of the silver nanoparticles reacted with sulfur and oxygen, changing their structure and function. These newly created silver compounds can be more stable and less toxic than the silver nanoparticles.Over time, though, they may build up in the environment, providing relatively large quantities of silver that can be incorporated into plants and animals. These long-term reservoirs of silver in soils and sediments may lead to increased exposures. For example, silver was found in plants that started growing six months after the nanoparticles were applied.Once changed, the newly formed silver compounds migrated through the soil and water. Runoff and erosion also moved the metal compounds and the nanoparticles. Eventually, the silver was taken up by the plants, insects and fish living in the mock ecosystems.Silver also passed from the mother fish to her embryos. The transfer of contaminants from one generation to the next exposes the embryos early in development and can have long-term effects on health, reproduction and populations (Wu et al. 2010).The effects on plants and other animals in this study are still unknown. Previous research indicates silver can harm fish, clams and other aquatic species.A next step may be to determine if these exposures have any health effects on the species studied. Scientists will also need to determine the levels of silver nanoparticles released into the environment from consumer products. Initial results from a study done on socks containing silver nanoparticles show more than 50 percent of the silver escapes during the first few washings (Geranio et al. 2009). It will also be important to identify the levels of silver nanoparticles that remain intact after release and to understand plant and animal exposures.As more data become available, it may be important to evaluate which products will benefit most from having the silver nanoparticles and which ones may not be worth the risk they may pose to health and environment.(Audrey Bone, Doctoral Student, Duke University, Integrated Toxicology and Environmental Health Program contributed to this synopsis.)

 

Read more science at Environmental Heath News.

Nano research leads to a greener lubricating oil.

Synopsis by Wim Thielemans, Sep 15, 2011

Majano, G, E-P Ng, L Lakiss and S Mintova, 2011. Nanosized molecular sieves utilized as an environmentally friendly alternative to antioxidants for lubricant oilsGreen Chemistry http://dx.doi.org/10.1039/c1gc15367f.

An environmentally-friendly, sieve-like nanomaterial can reduce the chemical fallout from the breakdown of lubricants better than the chemical additives now used.

Looking to solve an old problem in a new way, green chemists find that a special porous material can better reduce levels of dangerous breakdown byproducts in oil lubricants than the long-used but harmful chemicals now added. The team of researchers report their findings about the material – called zeolites – in a recent issue of Green Chemistry.

Lubricant oils reduce friction between moving parts in machines and motors in every part of society, including factory conveyor belts, cars and sewing machines. Synthetic mineral oils are used most often because they are more stable than other types. About 32 million tons of the lubricant oils leak and enter the environment every year.

To reduce human health impacts and meet new European regulatory standards, chemists are trying to find ways to make the oils both functional and environmentally benign.

One big problem with lubricants is they break down and form byproducts when exposed to oxygen – a process known as oxidation. Oxidation generates water, reactive alcohols and acids that increase corrosion and rust, thicken the lubricant, form sludge and sediment, break down the oil and create foam.

Chemical additives prevent or reduce the oxidative reactions. Unfortunately, most additives are dangerous and can impact human health and the environment. Some also affect the machine’s function, such as deactivating the catalyst converters in cars.

In this work, researchers from France, Belgium and Malaysia tested how a highly porous inorganic nanomaterial called zeolites absorb the initial oxidation products in an effort to reduce the harmful chemical byproducts that form. They did not try to stop oxidation like the current crop of chemical additives do. In theory, since oxidative reactions naturally speed up over time, removing the reaction products would reduce further oxidation, slow the process and create less harmful byproduct.

One of the three zeolites compared in the study worked surprisingly well. The researchers found the zeolite cleans up the process in two ways. First, it slowed the inherent oxidation reactions and reduced the amount of chemical byproduct produced. Second, it also absorbed the byproducts that formed. In the end, very little sludge was produced.

The zeolites used have no known adverse environmental effects and can even work together with existing oxidation-preventing chemical additives. The zeolites – when combined with perhaps a next generation of more benign additives – would then give added protection.

Future laboratory studies will need to test the performance of the numerous other zeolites available. From there, they must be tested and assessed in a real working environment. Even though this is not the final word on the technology, it looks to be very promising.

Read more science at Environmental Health News.

A more sensitive material detects heavy metals at 100 times lower levels.

Synopsis by Wim Thielemans, Aug 04, 2011

Zhang, Y, Y Liu, X Ji, CE Banks and W Zhang. 2011. Sea cucumber-like hydroxyapatite: Cation exchange membrane-assisted synthesis and its application in ultra-sensitive heavy metal detection. Chemical Communications http://dx.doi.org/10.1039/c1cc10489f.

A nano-sized membrane that looks like a hard, hairy sponge can detect minute amounts of lead and cadmium in water, report researchers who devised a new method in the laboratory to grow the natural material – called hydroxyapatite – that makes up the membrane.

Hydroxyapatite has unique properties that are already being exploited in a variety of sensors in an effort to move away from using gold, mercury and other toxic substances. The new method – which is still being researched – takes its use even further by developing crystal-like protrusions and structures that increase the material’s surface area. Its higher interaction with the surrounding water dramatically improves the material’s sensitivity; it can measure levels up to 100 times lower than other available devices.

Heavy metals such as lead and cadmium are a major health and environmental problem. They contaminate soil and water and accumulate in plants and animals. People are exposed to heavy metals through many sources, including food, water, air and dust. In humans, exposure to heavy metal is linked to many disorders such as organ damage, developmental problems and psychological changes.

Governments regulate heavy metal emissions, but the metals still contaminate many streams, lakes and other water bodies. As regulation tighten, it is thus important to monitor for these pollutants at more sensitive levels in waterways, tap water and drinking water.

The researchers grew the hydroxyapatite – which is a major component of human teeth and bones – on a membrame for four to seven days to create a crystal-like material with a high surface area. A higher surface area allows for increased surface-water interaction.

The hydroxyapatite can efficiently exchange calcium from its own structure with lead and cadmium in the water. The metal content in the water is then determined by applying a varying voltage over the hydroxyapatite and measuring the electrical current that flows through it.

The detection limit for lead was determined to be 9 X 10-10 grams per liter (g/L) – that is, a decimal point followed by nine zeros and a nine. Cadmium was detected down to 3 X 10-9 g/L. These detection limits are on the order of parts per trillion. They could detect a single drop in the volume of 20 Oympic size swimming pools. This makes the innovative material 10 to 100 times more sensitive than other hydroxyapatite-based sensors.

The high surface area hydroxyapatite was formed by controlling its growth using a Nafion membrane. Nafion is a polymer that allows only positive ions to pass through it. Hydroxyapatite was formed by combining two reactants – calcium and phosphate – added on opposite sides of the membrane in water. Only calcium – with its positive charge – can pass through the membrane The hydroxyapatite forms on the membrane’s surface as calcium reaches the other side and combines with the water and phosphate.

The new method to prepare high surface area hydroxyapatite is very promising. However, applying it to detect heavy metals will take further work to optimise. For example, the authors only tested their device to detect a single metal. They did not yet report the effectiveness when several metals are present or when other non-metallic pollutants are present in the water.

The researchers will also need to optimise how to form the high surface area hydroxyapatite. For wide use, faster preparation methods will need to be developed.

See more science at Environmental Health News.

Gold, palladium team up to clean up chemical-making process.

 

Kesavan, L, R Tiruvalam, MH Ab Rahim, MI bin Saiman, DI Enache, RL Jenkins, N Dimitratos, JA Lopez-Sanchez, SH Taylor, DW Knight, CJ Kiely and GJ Hutchings. 2011. Solvent-free oxidation of primary carbon-hydrogen bonds in toluene using Au-Pd alloy nanoparticles. Science http://dx.doi.org/10.1126/science.1198458.

 


Jun 07, 2011

 

2011-0606audreyshand
Audrey Moores
Chemists report a cleaner way to produce a much-used compound called benzylbenzoate.

A team of researchers have cleaned up the process to produce a versatile compound – called benzylbenzoate – that kills disease-causing mites, stabilizes fragrances and is a building block for pharmaceuticals. Benzylbenzoate is made from toluene – a cheap and readily available chemical in crude oil. The new process applies oxygen gas and toluene to a material made of carbon and tiny particles of metals gold and palladium. No solvents are used, and no waste byproducts are generated. The finding is also important because it is a stepping stone to a method to convert natural gas into a useful fuel like methanol.

 

 

Context

Adding an oxygen atom to a molecule – called oxidation – in a controlled fashion is a long sought but challenging goal of chemistry. The procedure is important because most molecules used in industrial and consumer applications have unique properties due to the exact position on the molecule of specific groups of atoms – their chemical functional groups. Many of these functional groups are oxygen based.

For example, introducing one oxygen atom would convert methane – the main component of natural gas and an abundant resource – into methanol, which could be used as a liquid fuel. While simple on paper, the actual transformation is challenging. It often leads to more than one oxygen attaching and ultimately, to the complete burning of methane into carbon dioxide.

More generally, the chemical industry heavily relies on molecules that contain oxygen at key positions. They are used as bulding blocks to make other chemicals. Among them, benzyl alcohol, benzaldehyde, benzoic acid and benzylbenzoate have important economical impacts. They constitute starting points in the manufacture of important products, such as pharmaceuticals, dyes, solvents, perfumes, plasticizers, preservatives and flame retardants.

But, harmful chemicals are needed to make this family of molecules. The process starts with a simple, carbon-based molecule called toluene. Toluene is a component of crude oil. Its transformation currently requires harsh processes involving chlorinated chemicals, acidic solvents or toxic metals. The process has very poor yields (around 15 percent) and generates copious quantities of waste.

Alternatives starting with biomass are desirable and intensely researched, but to date, no alternative process exists to create this important family of compounds.

Current research on oxidation reactions focuses on three key points. First, any required additive needs to be solid to ease separation. Second, the oxygen atom introduced should preferably come from oxygen gas present in air, as opposed to more wasteful or toxic sources. Third, the process must be very efficient – that is, yield a lot of material– and selective – create only one molecular product and thus limit separating the wheat – what’s wanted – from the chaff – what’s not – after the reaction.

What did they do?

The research team from the United Kingdom and the United States exposed toluene to oxygen at 160 degrees Celcius and 10 bars of oxygen – equivalent to 10 times normal atmospheric pressure – for two days. Under these conditions, a very small fraction – 2.9 percent – of toluene was converted into a mixture of benzaldehyde, benzoic acid and a small quantity of the desired benzylbenzoate.

Then, they tested several materials for their ability to improve the reaction. One was gold nanoparticles deposited onto titania, because it actively promotes oxidation of alcohols and carbon monoxide.

Gold nanoparticles deposited onto carbon – similar to porous charcoal – was also tested.

In another approach, they deposited tiny particles of gold and palladium inside the carbon pores. In this setting, gold and palladium form an alloy that has unique properties, different from both pure gold and pure palladium.

They also varied the proportion of gold and palladium in the system and measured how it was impacting the chemical process.

Each system was analyzed using two criteria: 1) conversion – the number of toluene molecules transformed – and 2) selectivity – Did one toluene transform into one or several kinds of molecules?

What did they find?

The gold and palladium nanoparticles on the porous carbon offered the best materials to spur the difficult reaction that transforms toluene to benzylbenzoate.

About half of the toluene was converted with this media. The process was very selective – 94.3 percent of the product was benzylbenzoate. This process required 6,500 times less metal than toluene.

The authors then tried to improve toluene conversion by altering the amount of metal. By adding more metal – 1,650 times less metal than toluene – they reached a conversion of 94.4 percent.

Researchers found that the other materials were not as good. Gold nanoparticles on titania did not perform well despite its other successes. Gold alone on carbon was not very active, either.

The mixture of the gold with palladium inside each nanoparticle proved essential to activity. The optimum proportion was 1 gold atom for 1.85 palladium atoms. Size mattered too, and a small size particle was critical to obtaining high conversion.

What does it mean?

In this work, researchers developed a novel material that takes oxygen from the air to transform toluene into the valuable benzyl benzoate. The material is composed of carbon, gold and palladium at specific ratios for optimum performance.

This research is very important because it brings chemists closer to defining the reaction that could convert methane from natural gas to methanol. Such a  process could allow two important developments.

First, methane is a flammable gas and is thus impractical and dangerous to use as a fuel for vehicles. Methanol, on the other side, is a liquid similar in properties to ethanol. Ethanol currently makes up a small fraction of automobile fuel sold in the United States.

Second, methanol has other important applications in the chemical industry. It is used as a solvent, as an antifreeze and as a building block for a host of commodity chemicals.

The new reaction is also remarkable because of its high yield, chemical selectivity, low waste and use of available resources. The use of a very simply reagent – oxygen gas from air – generated no waste.

The material was very convenient to use. After the reaction, the ending product separated completely from the starting material and was simply filtered off. This allows for two good things: 1) no metal or carbon ended up in the product and 2) the material can be reused in subsequent reactions. The materials was reused four times without measuring any alteration of reactivity.

The porous carbon support played an important role in the success of the reaction. The same material based on porous titania was less active. The researchers suggest the improved performance originates from the difference in surface structure between the carbon and titania based nanoparticles. They believe carbon causes the metal particles to be rougher and thus more reactive with the oxygen.

In all cases, the chemists did not detect any carbon dioxide waste. This means that the oxidation reaction – that is, adding an oxygen atom to the starting carbon, gold and palladium materials – proceeds well. Only one atom of oxygen is added, not several, which happens during complete combustion. This process affords a valuable chemical from toluene without burning toluene itself.

More development and studies are needed to turn this discovery into an industrial process.

Resources

Edwards, JK, B Solsona,E Ntainjua, AF Carley, AA Herzing, CJ Kiely, and GJ Hutchings. 2009. Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process. Science 323(5917):1037-1041.

Enache, DI, JK Edwards, P Landon, B Solsona-Espriu, AF Carley, AA Herzing, M Watanabe, CJ Kiely, DW Knight and GJ Hutchings. 2006. Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Au-Pd/TiO2 Catalysts. Science 311(5759):362-365.

Konietzni, F, U Kolb, U Dingerdissen, WF Maier. 1998. AMM-MnxSi-catalyzed selective oxidation of toluene. Journal of Catalysis 176(2):527-535.

Partenheimer, W. 1995. Methodology and scope of metal/bromide autoxidation of hydrocarbons. Catalysis Today 23(2): 69-158.

Saravanamurugan, S, M Palanichany, V Murugesan. 2004. Oxyfunctionalisation of toluene with activated t-butyl hydroperoxide. Applied Catalysis A General 273(1-2), 143-149.

Sheldon, RA, and JK Kochi. 1981. Metal-catalyzed oxidations of organic compounds. Academic Press:New York.

Under the light, gold shines as it depollutes phenol from water.

Navalon, S, M de Miguel, R Martin, M Alvaro and H Garcia. 2011. Enhancement of the catalytic activity of supported gold nanoparticles for the fenton reaction by light. Journal of the American Chemical Society http://dx.doi.org/10.1021/ja108816p.

Synopsis by Audrey Moores
May 26, 2011

Just about everything – from cars to laptops to cells to chemical reactions – needs energy to start up and keep going. Now, chemists in Spain have stumbled on a way to use light – the simplest and most abundant energy source – to speed up reactions that may be used to degrade a water pollutant, phenol.

The results suggest light can drive a chemical reaction that uses minute quantities of gold, titanium and oxygenated water to degrade a chemical pollutant known as phenol. They report the results of their laboratory study in the Journal of the American Chemical Society.

Phenol is a contaminant in industrial effluents and municipal sewage that is commonly found in rivers and lakes. It can occur naturally, but the bulk of it in waterways is produced from making resins for plastics and the building industry, nylon fabric and medicines. Phenol is an essential building block to make bisphenol A, a plasticizer that is widely used in the resins that line food and drink cans. Phenols are also used in medicines and personal care products, such as ointments, mouthwash and throat lozenges.

People are exposed to phenols by eating or breathing them at work or through medicines. Phenols can irritate skin and extended exposure to high levels can lead to loss of appetite, nervous system problems and cardiovascular conditions.

In this study, researchers showed that light could help gold nanoparticles drive a new kind of chemical reaction. The breakthrough may be a very applicable solution to a common problem of cleaning up contaminated water in streams, rivers and lakes.

Making and destroying a molecule takes energy. So using the sun as a source is a good idea. After all, plants build and maintain themselves using sunlight as unique energy source

Already a large number of light-promoted chemical reactions are at play in consumer products. For instance, some windowpanes used in large buildings have a self-cleaning technology. Very small pieces of a material called titania cover the surface of the glass. Titania can harvest UV light from the sun and break the pollutants that adhere to their surface down into carbon dioxide and water. But using sunlight to make reactions go still has limitations. Water treatments remain a challenge.

In this study, Hermenegildo Garcia and his group deposited gold nanoparticles onto small pieces of diamond. They added a mixture of a pollutant – phenol – and hydrogen peroxide – best known as oxygenated water – onto the materials. Then, they exposed the mixture to light and they observed degradation of phenol.

Normally, hydrogen peroxide is powerful enough to break phenol down. But, in the presence of the gold and diamond material and light, they saw something quite amazing. The reaction was up to 10 times faster. They also found that the more light was shed on the mixture, the faster the reaction. This proves the central role of light in this new process. The reaction proceeded using either laser light or sunlight.

They discovered even more. Phenol degradation requires very acidic conditions, usually uncommon in streams and other waterways. In the lab, under dark and neutral pH – non-acidic – conditions, no reactions occurred. But, again, as soon as light was shed on the mixture, the particles degraded phenol and it disappeared. The products of degradation of phenol are not discussed in the report.

More studies are needed to show the process can work outside of laboratory conditions. Challenges include studying the gold containing materials’ resistance to natural conditions and figuring out how to expose the particles evenly to light in the cleaning unit. However this research shows promise in developing strategies to clean up polluted water.

See original post in Environmental Health News

New energy source discovered?

New energy source discovered?

Posted by Adelina Voutchkova at Mar 16, 2010 09:50 AM | Environmental Health News

A CNN report on a “new energy source” needs scrutiny and more explanation so readers do not misinterpret the findings.

In a recent CNN article, Shelby Lin Erdman reports on a new development from MIT researchers who “discovered an energy source that you can see only through a microscope,”

The original research published in the journal Nature Materials describes a highly novel way of channeling energy generated by a chemical reaction through carbon nanotubes. This discovery has revolutionary implications for reducing the size of batteries and other devices, and as such should be applauded.

But, Erdman could have offered more information to clarify for readers the technology’s limitations, its long-term prospects and its potential toxicity. Simply including comments from one or more experts not involved in the development of the technology would have gone a long way to putting this story into context.

Firstly, the discovery is not an “energy source;” instead it is a new way of transmitting energy generated by a chemical reaction. Secondly, the realistic applications of this technology are still a long way from becoming a reality.

A third point concerns toxicity. The article’s senior author asserts that “batteries made from this new thermopower technology would be completely nontoxic.” While reassuring, this is not accurate. Recent research studies have repeatedly shown that carbon nanotubes – the nanomaterials used to make these new devices – are toxic to cells,  rats and mice.

The article further states that when burnt the devices would produce only carbon since these new “batteries” would be made of carbon-containing materials. While this is theoretically true, the process of making carbon nanotubes usually requires heavy metals – such as cobalt, nickel or iron – which become incorporated into the nanomaterials. Incinerating the tubes could produce toxic metal oxides, although little is understood about how nanomaterials behave under those circumstances.

In sum, while this article highlights an important step forward in the development of small energetic materials, by misinterpreting the science, the journalist gives readers an overly optimistic understanding of this discovery’s implications. This could be easily avoided by including opinions from other experts knowledgeable about the subject.