Gold nanoparticles improve technology to detect hazardous chemicals

The new system can pick out a single target molecule from 10 000 trillion water molecules within milliseconds, by trapping it on a self-assembling single layer of gold nanoparticles.
The team of LCN scientists from the Department of Chemistry at Imperial say this technology opens the way to develop devices that are compact, reusable and easy to assemble, and could have a range of uses including detecting illegal drugs, explosives, pollutants in rivers or nerve gases released into the air. Results of the research are published this week in Nature Materials (“Self-assembled nanoparticle arrays for multiphase trace analyte detection”).

In one potential use, such a device could detect tiny traces of explosives or other illegal substances left behind by criminals on the surfaces they touch. The advances made by this team would help law enforcers to identify and deal with such activities involving illegal substances.
Research co-author, Michael Cecchini, said: “Our system could solve a key problem of reliable and portable chemical testing for use in the outside world. It is very sensitive and could well be used to look for very small amounts of a specific molecule even in busy, public areas.”

The target molecules are identified by an effect called Surface Enhanced Raman Scattering (SERS) of light. This technique, which has been around since the late 1970’s, works because each molecule scatters light in a unique way. Previous research has shown that the signal can be amplified by catching molecules in a particular way on a layer of metal nanoparticles. However, these sheets are complex to manufacture.

The scientists overcame this problem by dealing with interfaces of two liquids that do not mix, such as water and oil, or water and air interface. By manipulating the electrical charge of the gold nanoparticles and the composition of the solution, they were able to create a situation where the particles line themselves up at the interface between the two non-mixable liquids, or between a liquid and the air.

“The trick to achieving this system’s sensitivity to the target molecules was in finding the conditions at which nanoparticles would settle at the interface at close distances to each other without fusing together”, commented another co-author Jack Paget.

If the nanoparticles are disturbed, they spontaneously arrange themselves back in the correct way make the device more robust than those made rigidly arranged particles. Research co-author, Vladimir Turek, said: “The system shows real promise for detectors for use in rough outdoor environmental and defence applications, since the liquids and nanoparticles can be easily replaced to regenerate the device.”

Source: By Joshua B. Edel, London Centre for Nanotechnology


Overview of nanomaterials for cleaning up the environment

Researchers have presented an extensive analysis of the role of nanomaterialsin environmental remediation and monitoring. Nanomaterials can be used to clean up toxins and bacteria from natural waters, wastewaters and the air (see paper in Energy & Environmental Science: “A review on nanomaterials for environmental remediation”).
Nanomaterials’ unique properties allow them to remove pollutants from the environment. The extremely small size of nanomaterial particles, typically in the range between 1 and 100 nanometres, creates a large surface area in relation to their volume, which makes them highly reactive, compared to non-nano forms of the same materials.
Silver, iron, gold, titanium oxides and iron oxides are some of the commonly used nanoscale metals and metal oxides cited by the researchers that can be used in environmental remediation. Silver nanoparticles, for example, have proved to be effective antimicrobial agents and can treat wastewater containing bacteria, viruses and fungi. Nanoscale titanium dioxide can also kill bacteria and disinfect water when activated by light.
Gold nanoparticles may potentially be another useful material for removing contaminants, such as toxic chlorinated organic compounds, pesticides and inorganic mercury, from water. They can also be used to remediate air. In combination with titanium dioxide, goldnanoparticles have been shown to convert the toxic air pollutant, sulphur dioxide, to sulphur. Titanium dioxide nanomaterials are commonly used in some processes to disinfect water, in addition to breaking down halogenated compounds, and removing dyes and metal toxins from drinking water and wastewater.
The researchers point to studies that show that carbon nanomaterials are particularly suited to removing a broad range of pollutants. Carbon nanotube clusters, for example, are used to purify water by adsorbing bacteria that contaminate the water. Heavy metals, such as cadmium, as well as organic pollutants including benzene and 1,2-dichlorobenzene can also be removed from water by carbon nanotube materials.
The researchers suggest that nanoparticles can be attached to host polymer materials, such as porous resins, cellulose and silica, to reduce potential harm to human health and the environment derived from the release of nanoparticles into the environment. The nanoparticles fixed to the host material are thus bulkier and can be more easily removed and captured from wastewater. Nanoparticles, such as nanoscale zinc oxide, fixed in this way, are used, for example, to break down organochlorine pesticides, halogenated herbicides and azo dyes.
In addition to remediating pollution, nanoparticles can be used as sensors to monitor toxins, heavy metals and organic contaminants in land, air and water environments and have been found to be more sensitive and selective than conventional sensors. Sensor strips composed of nylon 6 nano-fibre nets are one example. These are used to detect formaldehyde, a toxic air pollutant widely used in the manufacture of household materials and building products. The yellow sensor strips turn red upon exposure to formaldehyde.
The researchers acknowledge that ongoing work is needed to further improve the shape, sizes, structures, functionality and manufacture of nanomaterials that show promise in cleaning up contaminants that enter water, land and air environments from industries, transport and other human activities. A better understanding of the behaviour of nanomaterials and their potential harm to the environment is also required.

Graphene-based nanocomposite to adsorb water pollutants

(Nanowerk News) Researchers succeeded in the production of particles with smaller size but higher surface area, and consequently more number of active sites, to adsorb pollutants by synthesizing cerium oxide–titanium dioxide nanoparticles and obtaining cerium oxide–titanium dioxide nanocomposite (see paper in Journal of Hazardous Materials: “Assembly of CeO2–TiO2 nanoparticles prepared in room temperature ionic liquid on graphene nanosheets for photocatalytic degradation of pollutants”).
Among semi-conductive photocatalysts, titanium dioxide (TiO2) is an important candidate to be used in many industries due to its high optical stability and non-toxicity. However, it is impossible to use this component in visible light because its energy gap is placed in the range of ultraviolet.
In this research, researchers from Sharif University of Technology in association with researchers from University of Mohaghegh Ardebili and Nanoscience and Nanotechnology Research Center tried to move the energy gap of TiO2 towards longer wavelengths through the synthesis of carbon-based TiO2 / CeO2 nanocomposite. They also aimed to increase the photocatalytic activity of TiO2.
Results of the research showed that the synthesis of TiO2 in an ionic solution and the addition of cerium oxide to the structure of TiO2 decreased the particle size, increased the surface area, and slowed down the phase exchange from anatase to rutile at higher temperatures. As a result, it caused the creation of nanoparticles with higher thermal stability. High activity of the nanocomposite in the degradation of pollutants is explained by the unique structure of graphene, which increases adsorption on the catalyst surface and decreases the re-composition of ion carriers.

Bangkok Car Free Day this Sunday to raise awareness of global warming

Bangkok Metropolitan Administration (BMA) will be hosting Bangkok Car Free Day 2011 this Sunday with an aim to encourage the use of public transportation and reduce environmental impact from cars.

Deputy Bangkok Governor Mr. Theerachon Manomaipiboon presided over the launching of ‘Bangkok Car Free Day 2011’ today to raise the awareness of the global warming and encourage people to leave their cars at home and instead travel by public transportation or ride a bicycle on Sunday.


Catalytic Clothing that eats dirty air

HI-TECH denim jeans that use nanotechnology to stop air pollution are to go on show at the London Design Festival, which starts later this week.

Given recent reports that show London’s air to be among the filthiest in Europe, a clothing solution could be just up London’s street. Especially if that street is Oxford Street or any other area with a high number of pedestrians.

“A significant reduction in the level of air borne pollutants in a large city such as London could be achieved if, for every metre of pavement width, 30 people wearing Catalytic Clothes walked past each minute,” say developers Catalytic Clothing.

The jeans, or any other clothing fitted with the new technology, “harness the power of a photocatalyst to break down air borne pollutants,” by using light as an energy source.

“When the light shines on the photocatalyst, the electrons in the material are rearranged and they become more reactive,” adds the Catalytic Clothing website.

Further reactions then “cause pollutants to break down into non-harmful chemicals”.

Any material can become a pollution eater with the addition of a sort-of conditioner containing the photocatalysts, but different materials need different catalyst set-ups.

For the purposes of demonstration, jeans fit the bill since, “there are more pairs of jeans in existence than there are people on the earth,” as the Catalytic Clothing people put it.

The nanotech denim – developed by a team at Sheffield University and another at the London College of Fashion – has been formed into a display called The Field of Jeans for the London Design Festival, which runs from 17-25 September.

catalytic clothing faq

Hoover Air Purifier with TiO2 Technology

Hoover Air Purifier with TiO2 Technology – WH10600 (Hoover WH10600 air purifier) removes 99.9% of germs, bacteria and other microorganisms that pass through the UV light. It has the Titanium Dioxide (Ti02) coated screen that increases UV effectiveness. UV as well as Ti02 controls can be used during an entire year, especially during the flu period. There is a washable pre-filter integrated; it collects lint, pet hair, pollutants and other small particles. Depending on air quality the IntelliSense control system helps setting the fan speed to an appropriate level, so you don’t need to adjust it manually.

Features and Specifications

Hoover WH10600 is the air purifier that can be used in spaces of up to 79 sq ft. It helps remove allergens from the air making the air of your room or office fresh and the environment more desirable. This device has a Titanium Dioxide (Ti02) technology that helps removing 99.9% of airborne particles. They are collected to an elegant package and make this device to be a great part of your room design.

The Hepa filter collects 99.9% of dust and pollens, and thanks to the LED indicator, you will be informed when it is time to change the filter. The ionizer helps removing odors and airborne dust, pollen and germs; it is an environmentally friendly ionizer that uses no ozone for air cleaning.

The IntelliSense Control system sets the fan speed automatically depending on air quality. If needed, the unit can be adjusted choosing one of the three different fan speeds.

There is a remote control included that helps you making one-touch adjustments. You may want to set Hoover WH10600 for up to 24 hours – the device will shut off automatically which increases your comfort and allows you working on your tasks without returning to the unit. Moreover, the remote control can be used when the unit is 25 feet away from you.

Hoover WH10600 is 12.8 x 9.5 x 28 inches of size and weighs 13.3 pounds. Small in size and light this air purifier can be transported from one room to another easily.

Customer Reviews

To provide a better review of Hoover WH10600 air purifier, we provide a number of comments we’ve received from users or owners of this air purifier. Below you will find their positive and negative feedbacks that we hope will assist you making your choice.


Hoover WH10600 is recognized to be the best air purifier thanks to its great performance. As many users noticed, the air becomes fresh and the entire space is more desirable: “I have it in my office at work, and every time a co-worker comes in, they make mention of how fresh the air in my office smells. It’s a dramatic and noticeable difference from the air in the rest of the building.” We also received the following comment: “Its now been nearly 3 hours on the highest setting and everything “On” and I am definitely breathing cleaner air. I even let my roommate smoke in the condo to test it out, within 3 minutes and some Febreeze I couldn’t smell any smoke.”

We also received a couple of comments regarding how silent the air purifier works. As the reviewer noticed: “On level 1 the unit is virtually silent, 2 and especially 3, produce a bit of noise but the noise is comparable to other units I have used in the past.”

This air purifier can be also used in the kitchen. One lady said she tried using this air purifier while cooking bacon: “I have a small kitchen and even with turning on the stove hood vent, it can get kinda smokey especially when frying bacon. That’s why I thought this would be a great test. I won’t say it eliminated all of the smoke and odor, but it clearly did decrease the odor and amount of time it lasted throughout my kitchen and living room. I was impressed.”

The Pros:

The Titanium Dioxide coated screen for an increased UV effectiveness
99.9% or germs, bacteria and other pollutants removed
UV light removing particles passing through the screen under the UV light
IntelliSense Control system to follow air quality and adjust the unit accordingly

The Cons:

A couple of Hoover WH10600 users were not happy about the LED light. They commented it is too bright and may bother. We ensure that the light is not going to keep you awake in the night, and can be easily covered.

Overall Rating

After a deep analysis of Hoover Air Purifier with TiO2 Technology – WH10600 we affirm it to be the best air purifier. It’s compact and can be transformed easily. You may use it at home or in the office. The UV light and Ti02 technologies are other great features of this unit. With all these features we find it to be the best purifier within this price range.

If you are looking for in-depth reviews of all the best air purifiers such as the Rabbit Air BioGS SPA-421A, visit the Best air purifier website. We also reveal where to purchase the most popular air purifiers for up to 40% off.


Google’s Electricity consumption

Internet search giant Google says that it consumed about 2.26 billion kilowatt hours of electricity last year, equal to the energy used in 200,000 homes. But while that represents an enormous amount of energy, Google says the services supported by its expanding data centers reduce energy use globally and allow users to improve their own energy efficiency. In its official blog, the company said the typical user of Google’s products — including search, Gmail, and YouTube — uses about 180 watt-hours monthly accessing those services, or less than “a light left on for three hours.” It’s the first time Google has shared information on its energy use and greenhouse gas emissions, an attempt to be more transparent as it expands its data center operations worldwide — including a new center in Finland — and promotes its cloud-based data services. The company also disclosed that it emitted about 1.46 million metric tons of carbon dioxide in 2010, but said that about one-quarter of its electricity came from renewable energy sources. The company also buys carbon offsets for its emissions.