Wood Mixed With Nanoparticles Filters Toxic Water

Engineers at the University of Maryland have developed a new use for wood: to filter water. Liangbing Hu of the Energy Research Center and his colleagues added nanoparticles to wood, then used it to filter toxic dyes from water.

The team started with a block of linden wood, which they then soaked in palladium – a metal used in cars’ catalytic converters to remove pollutants from the exhaust. In this new filter, the palladium bonds to particles of dye. The wood’s natural channels, that once moved water and nutrients between the leaves and roots, now allow the water to flow past the nanoparticles for efficient removal of the toxic dye particles. The water, tinted with methylene blue, slowly drips through the wood and comes out clear.

VIDEO: Wood filter removes toxic dye from water

This could be used in areas where wastewater contains toxic dye particles,” said Amy Gong, a materials science graduate student, and co-first author of the research paper.

The purpose of the study was to analyze wood via an engineering lens. The researchers did not compare the filter to other types of filters; rather, they wanted to prove that wood can be used to remove impurities.

We are currently working on using a wood filter to remove heavy metals, such as lead and copper, from water,’ said Liangbing Hu, the lead researcher on the project. “We are also interested in scaling up the technology for real industry applications.” Hu is a professor of materials science and a member of the University of Maryland’s Energy Research Center.

Source: http://www.mse.umd.edu/

Acidity In Atmosphere Produced By Industries Has Vanished

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Researchers from the University of Copenhagen (Denmark) have shown that human pollution of the atmosphere with acid is now almost back to the level that it was before the pollution started with industrialisation in the 1930s.  The Greenland ice sheet is a unique archive of the climate and atmospheric composition far back in time. The ice sheet is made up of snow that falls and never melts, but rather remains year after year and is gradually compressed into ice. By drilling ice cores down through the kilometre-thick ice sheet, the researchers can analyse every single annual layer, which can tell us about past climate change and concentration of greenhouse gases and pollutants in the atmosphere.

Acid in the atmosphere can come from large volcanic eruptions and manmade emissions from industry. You can measure acidity in the ice by simply passing an instrument that can measure conductivity over the ice core. If there is a high level of acidity, the measurement turns out and it works great for measuring the climate of the past all the way back to the last interglacial period 125,000 years ago. But if you want to measure atmospheric acidity for the last 100 years, it is more difficult as the annual layers are located in the uppermost 60 metres and there the ice is more porous as it has not yet been compressed into hard ice. But the last 100 years are interesting for climate researchers as it is the period where we have had massive pollution of the atmosphere from industrialisation, vehicle use and people’s energy consuming lifestyles.

banquiseWe have therefore developed a new method that can directly measure the acidity of the ice using a spectrometer. We have an ice rod that is cut along the length of the ice core. This ice core rod is slowly melted and the meltwater runs into a laboratory where they take a lot of chemical measurements. With our new method you can also measure the acidity, that is to say, we measure the pH value and this is seen when the water changes colour after the addition of a pH dye. We can directly see the fluctuations from year to year,” explains Helle Astrid Kjær, postdoc in the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.

The results come from studies of the Greenland ice sheet and are published in the scientific journal, Environmental Science and Technology.

Source: http://news.ku.dk/

Laboratories-On-a-Chip

Newly developed tiny antennas, likened to spotlights on the nanoscale, offer the potential to measure food safety, identify pollutants in the air and even quickly diagnose and treat cancer, according to the Australian scientists who created them. The new antennas are cubic in shape. They do a better job than previous spherical ones at directing an ultra-narrow beam of light where it is needed, with little or no loss due to heating and scattering, they say.

In a paper published in the Journal of Applied Physics, from AIP Publishing, Debabrata Sikdar of Monash University in Victoria, Australia, and colleagues describe these and other envisioned applications for their nanocubes in “laboratories-on-a-chip.” The cubes, composed of insulating, rather than conducting or semiconducting materials as were the spherical versions, are easier to fabricate as well as more effective, he says.

Sikdar’s paper presents analysis and simulation of 200-nanometer dielectric (nonconductive) nanoncubes placed in the path of visible and near-infrared light sources. The nanocubes are arranged in a chain, and the space between them can be adjusted to fine-tune the light beam as needed for various applications. As the separation between cubes increases, the angular width of the beam narrows and directionality improves, the researchers say.

nanoantennas
Unidirectional nanoantennas induce directionality to any omnidirectional light emitters like microlasers, nanolasers or spasers, and even quantum dots,” Sikdar said in an interview. Spasers are similar to lasers, but employ minute oscillations of electrons rather than light. Quantum dots are tiny crystals that produce specific colors, based on their size, and are widely used in color televisions. “Analogous to nanoscale spotlights, the cubic antennas focus light with precise control over direction and beam width,” he said.
Source: http://www.aip.org/

NanoFiber Mask Against Lethal Diesel Pollution

When a silver grey haze descends upon Hong Kong in springtime, would you wonder if it is harmful to your lungs? Haze is usually composed of pollutants in the form of tiny suspended particles or fine mists/droplets emitted from vehicles, coal-burning power plants and factories. Continued exposure increases the risk of developing respiratory problems, heart diseases and lung cancer. Can we avoid the unhealthy air? A simple face mask which can block out suspended particles has been developed by scientists from the Department of Mechanical Engineering at The Hong Kong Polytechnic University (PolyU). The project is led by Professor Wallace Woon-Fong Leung, a renowned filtration expert, who has spent his career understanding these invisible killers.

In Hong Kong, suspended particles PM 10 and PM 2.5 are being monitored. PM 10 refers to particles that are 10 microns (or micrometres) in size or smaller, whereas PM 2.5 measures 2.5 microns or smaller.

The nanofibre filter can capture diesel dust effectively
In my view, nano-aerosols (colloid of fine solid particles or liquid droplets of sub-micron to nano-sizes), such as diesel emissions, are the most lethal for three reasons. First, they are in their abundance by number suspended in the air. Second, they are too small to be filtered out using current technologies. Third, they can pass easily through our lungs and work their way into our respiratory systems, and subsequently our vascular, nervous and lymphatic systems, doing the worst kind of harm”, said Professor Leung, At the forefront of combating air pollution. Leung targets ultra-fine pollutants that have yet been picked up by air quality monitors – particles measuring 1 micron or below, which he perceived to be a more important threat to human health.

Source: http://www.polyu.edu.hk/