Rapid Nano-filter for clean water: Australian researchers design a rapid nano-filter that cleans dirty water 100X faster than current technology


quickandnots
The new technology can filter drinking water 100 times faster than current tech. Credit: Free stock photo 

Australian researchers have designed a rapid nano-filter that can clean dirty water over 100 times faster than current technology.

Simple to make and simple to scale up, the technology harnesses naturally occurring nano-structures that grow on .

The RMIT University and University of New South Wales (UNSW) researchers behind the innovation have shown it can filter both heavy metals and oils from water at extraordinary speed.

RMIT researcher Dr. Ali Zavabeti said water contamination remains a significant challenge globally—1 in 9 people have no clean water close to home.

“Heavy  contamination causes serious health problems and children are particularly vulnerable,” Zavabeti said.

“Our new nano-filter is sustainable, environmentally-friendly, scalable and low cost.

“We’ve shown it works to remove lead and oil from water but we also know it has potential to target other common contaminants.

“Previous research has already shown the materials we used are effective in absorbing contaminants like mercury, sulfates and phosphates.

“With further development and commercial support, this new nano-filter could be a cheap and ultra-fast solution to the problem of .”

Quick and not-so-dirty: A rapid nano-filter for clean water
A liquid metal droplet with flakes of aluminium oxide compounds grown on its surface. Each 0.03mm flake is made up of about 20,000 nano-sheets stacked together. Credit: RMIT University

The liquid metal chemistry process developed by the researchers has potential applications across a range of industries including electronics, membranes, optics and catalysis.

“The technique is potentially of significant industrial value, since it can be readily upscaled, the liquid metal can be reused, and the process requires only short reaction times and low temperatures,” Zavabeti said.

Project leader Professor Kourosh Kalantar-zadeh, Honorary Professor at RMIT, Australian Research Council Laureate Fellow and Professor of Chemical Engineering at UNSW, said the liquid metal chemistry used in the process enabled differently shaped nano-structures to be grown, either as the atomically thin sheets used for the nano-filter or as nano-fibrous structures.

“Growing these materials conventionally is power intensive, requires high temperatures, extensive processing times and uses toxic metals. Liquid metal chemistry avoids all these issues so it’s an outstanding alternative.”

How it works

The groundbreaking technology is sustainable, environmentally-friendly, scalable and low-cost.

The researchers created an alloy by combining gallium-based liquid metals with aluminium.

When this alloy is exposed to water, nano-thin sheets of  compounds grow naturally on the surface.

These atomically thin layers—100,000 times thinner than a human hair—restack in a wrinkled fashion, making them highly porous.

Quick and not-so-dirty: A rapid nano-filter for clean water
Microscope image of nano-sheets, magnified over 11,900 times. Credit: RMIT University

This enables water to pass through rapidly while the aluminium oxide compounds absorbs the contaminants.

Experiments showed the nano-filter made of stacked atomically thin sheets was efficient at removing lead from water that had been contaminated at over 13 times safe drinking levels, and was highly effective in separating oil from water.

The process generates no waste and requires just aluminium and , with the liquid metals reused for each new batch of nano-structures.

The method developed by the researchers can be used to grow nano-structured materials as ultra-thin sheets and also as nano-fibres.

These different shapes have different characteristics—the ultra-thin sheets used in the nano-filter experiments have high mechanical stiffness, while the nano-fibres are highly translucent.

The ability to grow materials with different characteristics offers opportunities to tailor the shapes to enhance their different properties for applications in electronics, membranes, optics and catalysis.

The research is funded by the Australian Research Council Centre for Future Low-Energy Electronics Technologies (FLEET).

The findings are published in the journal Advanced Functional Materials.

 Explore further: Liquid metal discovery ushers in new wave of chemistry and electronics

More information: Advanced Functional Materials (2018). DOI: 10.1002/adfm.201804057

 

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Making Hydrogen Production Cheaper using New Ultra-Thin nano-material for splitting water


newultrathinThis is a water drop falling into water. Credit: Sarp Saydam/UNSW

UNSW Sydney chemists have invented a new, cheap catalyst for splitting water with an electrical current to efficiently produce clean hydrogen fuel.

The technology is based on the creation of ultrathin slices of porous metal-organic complex coated onto a foam electrode, which the researchers have unexpectedly shown is highly conductive of electricity and active for .

“Splitting water usually requires two different catalysts, but our catalyst can drive both of the reactions required to separate water into its two constituents, oxygen and hydrogen,” says study leader Associate Professor Chuan Zhao.

“Our fabrication method is simple and universal, so we can adapt it to produce ultrathin nanosheet arrays of a variety of these materials, called .

“Compared to other water-splitting electro-catalysts reported to date, our is also among the most efficient,” he says.

The UNSW research by Zhao, Dr Sheng Chen and Dr Jingjing Duan is published in the journal Nature Communications.

Hydrogen is a very good carrier for renewable energy because it is abundant, generates zero emissions, and is much easier to store than other energy sources, like solar or wind energy.

But the cost of producing it by using electricity to split water is high, because the most efficient catalysts developed so far are often made with precious metals, like platinum, ruthenium and iridium.

The catalysts developed at UNSW are made of abundant, non-precious metals like nickel, iron and copper. They belong to a family of versatile porous materials called , which have a wide variety of other potential applications.

Until now, metal-organic frameworks were considered poor conductors and not very useful for electrochemical reactions. Conventionally, they are made in the form of bulk powders, with their catalytic sites deeply embedded inside the pores of the material, where it is difficult for the water to reach.

By creating nanometre-thick arrays of metal-organic frameworks, Zhao’s team was able to expose the pores and increase the surface area for electrical contact with the .

“With nanoengineering, we made a unique metal-organic structure that solves the big problems of conductivity, and access to active sites,” says Zhao.

“It is ground-breaking. We were able to demonstrate that metal-organic frameworks can be highly conductive, challenging the common concept of these materials as inert electro-catalysts.”

Metal-organic frameworks have potential for a large range of applications, including fuel storage, drug delivery, and carbon capture. The UNSW team’s demonstration that they can also be highly conductive introduces a host of new applications for this class of material beyond electro-catalysis.

Explore further: Researchers report new, more efficient catalyst for water splitting

More information: Jingjing Duan et al, Ultrathin metal-organic framework array for efficient electrocatalytic water splitting, Nature Communications (2017). DOI: 10.1038/ncomms15341

 

 

Non-toxic and cheap thin-film solar cells for ‘zero-energy’ buildings


Non Toxic Solar Cells 042816 160428103023_1_540x360Dr Xiaojing Hao of UNSW’s Australian Centre for Advanced Photovoltaics holding the new CZTS solar cells.
Credit: Quentin Jones/UNSW

World’s highest efficiency rating achieved for CZTS thin-film solar cells

‘Zero-energy’ buildings — which generate as much power as they consume — are now much closer after a team at Australia’s University of New South Wales achieved the world’s highest efficiency using flexible solar cells that are non-toxic and cheap to make.

Until now, the promise of ‘zero-energy’ buildings been held back by two hurdles: the cost of the thin-film solar cells (used in façades, roofs and windows), and the fact they’re made from scarce, and highly toxic, materials.

That’s about to change: the UNSW team, led by Dr Xiaojing Hao of the Australian Centre for Advanced Photovoltaics at the UNSW School of Photovoltaic and Renewable Energy Engineering, have achieved the world’s highest efficiency rating for a full-sized thin-film solar cell using a competing thin-film technology, known as CZTS.

NREL, the USA’s National Renewable Energy Laboratory, confirmed this world leading 7.6% efficiency in a 1cm2 area CZTS cell this month.

Unlike its thin-film competitors, CZTS cells are made from abundant materials: copper, zinc, tin and sulphur.

And CZTS has none of the toxicity problems of its two thin-film rivals, known as CdTe (cadmium-telluride) and CIGS (copper-indium-gallium-selenide). Cadmium and selenium are toxic at even tiny doses, while tellurium and indium are extremely rare.

“This is the first step on CZTS’s road to beyond 20% efficiency, and marks a milestone in its journey from the lab to commercial product,” said Hao, named one of UNSW’s 20 rising stars last year. “There is still a lot of work needed to catch up with CdTe and CIGS, in both efficiency and cell size, but we are well on the way.”

“In addition to its elements being more commonplace and environmentally benign, we’re interested in these higher bandgap CZTS cells for two reasons,” said Professor Martin Green, a mentor of Dr Hao and a global pioneer of photovoltaic research stretching back 40 years.

“They can be deposited directly onto materials as thin layers that are 50 times thinner than a human hair, so there’s no need to manufacture silicon ‘wafer’ cells and interconnect them separately,” he added. “They also respond better than silicon to blue wavelengths of light, and can be stacked as a thin-film on top of silicon cells to ultimately improve the overall performance.”

By being able to deposit CZTS solar cells on various surfaces, Hao’s team believe this puts them firmly on the road to making thin-film photovoltaic cells that can be rigid or flexible, and durable and cheap enough to be widely integrated into buildings to generate electricity from the sunlight that strikes structures such as glazing, façades, roof tiles and windows.

However, because CZTS is cheaper — and easier to bring from lab to commercialisation than other thin-film solar cells, given already available commercialised manufacturing method — applications are likely even sooner. UNSW is collaborating with a number of large companies keen to develop applications well before it reaches 20% efficiency — probably, Hao says, within the next few years.

“I’m quietly confident we can overcome the technical challenges to further boosting the efficiency of CZTS cells, because there are a lot of tricks we’ve learned over the past 30 years in boosting CdTe and CIGS and even silicon cells, but which haven’t been applied to CZTS,” said Hao.

Currently, thin-film photovoltaic cells like CdTe are used mainly in large solar power farms, as the cadmium toxicity makes them unsuitable for residential systems, while CIGS cells is more commonly used in Japan on rooftops.

First Solar, a US$5 billion behemoth that specialises in large-scale photovoltaic systems, relies entirely on CdTe; while CIGS is the preferred technology of China’s Hanergy, the world’s largest thin-film solar power company.

Thin-film technologies such as CdTe and CIGS are also attractive because they are physically flexible, which increases the number of potential applications, such as curved surfaces, roofing membranes, or transparent and translucent structures like windows and skylights.

But their toxicity has made the construction industry — mindful of its history with asbestos — wary of using them. Scarcity of the elements also renders them unattractive, as price spikes are likely as demand rises. Despite this, the global market for so-called Building-Integrated Photovoltaics (BIPV) is already valued at US$1.6 billion.

Hao believes CZTS’s cheapness, benign environmental profile and abundant elements may be the trigger that finally brings architects and builders onboard to using thin-film solar panels more widely in buildings.

Until now, most architects have used conventional solar panels made from crystalline silicon. While these are even cheaper than CZTS cells, they don’t offer the same flexibility for curved surfaces and other awkward geometries needed to easily integrate into building designs.


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The above post is reprinted from materials provided byUniversity of New South Wales. The original item was written by Wilson da Silva. Note: Materials may be edited for content and length.

Researchers set world record in solar energy efficiency


KAUST Solar ic8dbMM9X_FMMon, 12/08/2014 – 8:27am
Univ. of New South Wales
 

Univ. of New South Wales (UNSW)’s solar researchers have converted over 40% of the sunlight hitting a solar system into electricity, the highest efficiency ever reported.

The world-beating efficiency was achieved in outdoor tests in Sydney, before being independently confirmed by the National Renewable Energy Laboratory (NREL) at their outdoor test facility in the U.S. 

The work was funded by the Australian Renewable Energy Agency (ARENA) and supported by the Australia–U.S. Institute for Advanced Photovoltaics (AUSIAPV)

“This is the highest efficiency ever reported for sunlight conversion into electricity,” UNSW Scientia Professor and Director of the Australian Centre for Advanced Photovoltaics (ACAP) Prof. Martin Green said.

“We used commercial solar cells, but in a new way, so these efficiency improvements are readily accessible to the solar industry,” added Dr. Mark Keevers, the UNSW solar scientist who managed the project.

The 40% efficiency milestone is the latest in a long line of achievements by UNSW solar researchers spanning four decades. These include the first photovoltaic system to convert sunlight to electricity with over 20% efficiency in 1989, with the new result doubling this performance.

“The new results are based on the use of focused sunlight, and are particularly relevant to photovoltaic power towers being developed in Australia,” Prof. Green said.

Power towers are being developed by Australian company, RayGen Resources, which provided design and technical support for the high efficiency prototype. Another partner in the research was Spectrolab, a U.S.–based company that provided some of the cells used in the project.

A key part of the prototype’s design is the use of a custom optical bandpass filter to capture sunlight that is normally wasted by commercial solar cells on towers and convert it to electricity at a higher efficiency than the solar cells themselves ever could. 

Such filters reflect particular wavelengths of light while transmitting others.

ARENA CEO Ivor Frischknecht said the achievement is another world first for Australian research and development and further demonstrates the value of investing in Australia’s renewable energy ingenuity.

“We hope to see this home grown innovation take the next steps from prototyping to pilot scale demonstrations. Ultimately, more efficient commercial solar plants will make renewable energy cheaper, increasing its competitiveness.”

The 40% efficiency achievement is outlined in a paper in Progress in Photovoltaics.

Source: Univ. of New South Wales

New theranostic nanoparticle delivers, tracks cancer drugs


201306047919620(Nanowerk News) University of New South Wales (UNSW)  chemical engineers have synthesised a new iron oxide nanoparticle that delivers  cancer drugs to cells while simultaneously monitoring the drug release in real  time.
The result, published online in the journal ACS Nano (“Using Fluorescence Lifetime Imaging Microscopy to  Monitor Theranostic Nanoparticle Uptake and Intracellular Doxorubicin  Release”), represents an important development for the emerging field of  theranostics – a term that refers to nanoparticles that can treat and diagnose  disease.
Iron oxide nanoparticles that can track drug delivery will  provide the possibility to adapt treatments for individual patients,” says  Associate Professor Cyrille Boyer from the UNSW School of Chemical Engineering.
By understanding how the cancer drug is released and its effect  on the cells and surrounding tissue, doctors can adjust doses to achieve the  best result.
Importantly, Boyer and his team demonstrated for the first time  the use of a technique called fluorescence lifetime imaging to monitor the drug  release inside a line of lung cancer cells.
“Usually, the drug release is determined using model experiments  on the lab bench, but not in the cells,” says Boyer. “This is significant as it  allows us to determine the kinetic movement of drug release in a true biological  environment.”
Magnetic iron oxide nanoparticles have been studied widely  because of their applications as contrast agents in magnetic resonance imaging,  or MRI. Several recent studies have explored the possibility of equipping these  contrast agents with drugs.
However, there are limited studies describing how to load  chemotherapy drugs onto the surface of magnetic iron oxide nanoparticles, and no  studies that have effectively proven that these drugs can be delivered inside  the cell. This has only been inferred.
With this latest study, the UNSW researchers engineered a new  way of loading the drugs onto the nanoparticle’s polymer surface, and  demonstrated for the first time that the particles are delivering their drug  inside the cells.
“This is very important because it shows that bench chemistry is  working inside the cells,” says Boyer. “The next step in the research is to move  to in-vivo applications.”
Source: University of New South Wales

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