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A graphene membrane. Credit: The University of Manchester

 

“By 2025 the UN expects that 14% of the world’s population will encounter water scarcity.”

Graphene-oxide membranes have attracted considerable attention as promising candidates for new filtration technologies. Now the much sought-after development of making membranes capable of sieving common salts has been achieved.

New research demonstrates the real-world potential of providing for millions of people who struggle to access adequate clean water sources.

The new findings from a group of scientists at The University of Manchester were published today in the journal Nature Nanotechnology. Previously graphene-oxide membranes have shown exciting potential for gas separation and water filtration.

Graphene-oxide membranes developed at the National Graphene Institute have already demonstrated the potential of filtering out small nanoparticles, organic molecules, and even large salts. Until now, however, they couldn’t be used for sieving common salts used in technologies, which require even smaller sieves.

Previous research at The University of Manchester found that if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, but larger ions or molecules are blocked.

The Manchester-based group have now further developed these and found a strategy to avoid the swelling of the membrane when exposed to water. The in the membrane can be precisely controlled which can sieve common salts out of salty water and make it safe to drink.

As the effects of climate change continue to reduce modern city’s water supplies, wealthy modern countries are also investing in desalination technologies. Following the severe floods in California major wealthy cities are also looking increasingly to alternative water solutions.

WEF 2017 graphene-water-071115-rtrde3r1-628x330 (2)World Economic Forum: Can Graphene Make the World’s Water Clean?

 

 

 

 

When the common salts are dissolved in water, they always form a ‘shell’ of around the salts molecules. This allows the tiny capillaries of the graphene-oxide membranes to block the from flowing along with the water. Water molecules are able to pass through the membrane barrier and flow anomalously fast which is ideal for application of these membranes for desalination.

Professor Rahul Nair, at The University of Manchester said: “Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination .

“This is the first clear-cut experiment in this regime. We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes.”

Mr. Jijo Abraham and Dr. Vasu Siddeswara Kalangi were the joint-lead authors on the research paper: “The developed membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.” said Mr. Abraham.

By 2025 the UN expects that 14% of the world’s population will encounter water scarcity. This technology has the potential to revolutionize water filtration across the world, in particular in countries which cannot afford large scale desalination plants.

It is hoped that graphene-oxide systems can be built on smaller scales making this technology accessible to countries which do not have the financial infrastructure to fund large plants without compromising the yield of fresh produced.

Explore further: Researchers develop hybrid nuclear desalination technique with improved efficiency

More information: Tunable sieving of ions using graphene oxide membranes, Nature Nanotechnology, nature.com/articles/doi:10.1038/nnano.2017.21

MIT-Nanoscrolls-1_0

Researchers create perfect nanoscrolls from graphene’s imperfect form.

Water filters of the future may be made from billions of tiny, graphene-based nanoscrolls. Each scroll, made by rolling up a single, atom-thick layer of graphene, could be tailored to trap specific molecules and pollutants in its tightly wound folds. Billions of these scrolls, stacked layer by layer, may produce a lightweight, durable, and highly selective water purification membrane.

But there’s a catch: Graphene does not come cheap. The material’s exceptional mechanical and chemical properties are due to its very regular, hexagonal structure, which resembles microscopic chicken wire. Scientists take great pains in keeping graphene in its pure, unblemished form, using processes that are expensive and time-consuming, and that severely limit graphene’s practical uses.

Seeking an alternative, a team from MIT and Harvard University is looking to graphene oxide — graphene’s much cheaper, imperfect form. Graphene oxide is graphene that is also covered with oxygen and hydrogen groups. The material is essentially what graphene becomes if it’s left to sit out in open air. The team fabricated nanoscrolls made from graphene oxide flakes and was able to control the dimensions of each nanoscroll, using both low- and high-frequency ultrasonic techniques. The scrolls have mechanical properties that are similar to graphene, and they can be made at a fraction of the cost, the researchers say.

“If you really want to make an engineering structure, at this point it’s not practical to use graphene,” says Itai Stein, a graduate student in MIT’s Department of Mechanical Engineering. “Graphene oxide is two to four orders of magnitude cheaper, and with our technique, we can tune the dimensions of these architectures and open a window to industry.”

Stein says graphene oxide nanoscrolls could also be used as ultralight chemical sensors, drug delivery vehicles, and hydrogen storage platforms, in addition to water filters. Stein and Carlo Amadei, a graduate student at Harvard University, have published their results in the journalNanoscale.

Getting away from crumpled graphene

The team’s paper originally grew out of an MIT class, 2.675 (Micro/Nano Engineering), taught by Rohit Karnik, associate professor of mechanical engineering. As part of their final project, Stein and Amadei teamed up to design nanoscrolls from graphene oxide. Amadei, as a member of Professor Chad Vecitis’ lab at Harvard University, had been working with graphene oxide for water purification applications, while Stein was experimenting with carbon nanotubes and other nanoscale architectures, as part of a group led by Brian Wardle, professor of aeronautics and astronautics at MIT.

The researchers’ graphene nano scroll research originated in this MIT classes 2.674 and 2.675 (Micro/Nano Engineering Laboratory).

Video: Department of Mechanical Engineering

“Our initial idea was to make nanoscrolls for molecular adsorption,” Amadei says. “Compared to carbon nanotubes, which are closed structures, nanoscrolls are open spirals, so you have all this surface area available to manipulate.”

“And you can tune the separation of a nanoscroll’s layers, and do all sorts of neat things with graphene oxide that you can’t really do with nanotubes and graphene itself,” Stein adds.

When they looked at what had been done previously in this field, the students found that scientists had successfully produced nanoscrolls from graphene, though with very complicated processes to keep the material pure. A few groups had tried doing the same with graphene oxide, but their attempts were literally deflated.

“What was out there in the literature was more like crumpled graphene,” Stein says. “You can’t really see the conical nature. It’s not really clear what was made.”

Collapsing bubbles

Stein and Amadei first used a common technique called the Hummers’ method to separate graphite flakes into individual layers of graphene oxide. They then placed the graphene oxide flakes in solution and stimulated the flakes to curl into scrolls, using two similar approaches: a low-frequency tip-sonicator, and a high-frequency custom reactor.

The tip-sonicator is a probe made of piezoelectric material that shakes at a low, 20Hz frequency when voltage is applied. When placed in a solution, the tip-sonicator produces sound waves that stir up the surroundings, creating bubbles in the solution.

Similarly, the group’s reactor contains a piezoelectric component that is connected to a circuit. As voltage is applied, the reactor shakes — at a higher, 390 Hz frequency compared with the tip-sonicator — creating bubbles in the solution within the reactor.

Stein and Amadei applied both techniques to solutions of graphene oxide flakes and observed similar effects: The bubbles that were created in solution eventually collapsed, releasing energy that caused the flakes to spontaneously curl into scrolls. The researchers found they could tune the dimensions of the scrolls by varying the treatment duration and the frequency of the ultrasonic waves. Higher frequencies and shorter treatments did not lead to significant damage of the graphene oxide flakes and produced larger scrolls, while low frequencies and longer treatment times tended to cleave flakes apart and create smaller scrolls.

While the group’s initial experiments turned a relatively low number of flakes — about 10 percent — into scrolls, Stein says both techniques may be optimized to produce higher yields. If they can be scaled up, he says the techniques can be compatible with existing industrial processes, particularly for water purification.

“If you can make this in large scales and it’s cheap, you could make huge bulk samples of filters and throw them out in the water to remove all sorts of contaminants,” Stein says.

This work was supported, in part, by the Department of Defense through the National Defense Science and Engineering Graduate (NDSEG) fellowship program.

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California Ground Water Shortage 033016 GettyImages-468519400.0.0California Ground Water Shortage 033016 GettyImages-468519400.0.0water 061715 california-getty

Some of the world’s most important farming regions rely on freshwater from large underground aquifers that have filled up slowly over thousands of years. Think of the Central Valley aquifer system in California. Or the Indus basin in Pakistan and India. This groundwater is particularly valuable when rain is scarce or during droughts.

But that groundwater may not last forever. Data from NASA’s Grace satellites suggests that 13 of the world’s 37 biggest aquifers are being seriously depleted by irrigation and other uses much faster than they can be recharged by rain or runoff. And, disturbingly, we don’t even know how much water is left in these basins. That’s according to a 2015 paper in Water Resources Research.

The map below gives an overview. There were 21 major groundwater basins — in red, orange, and yellow — that lost water faster than they could be recharged between 2003 and 2013. The 16 major aquifers in blue, by contrast, gained water during that period. Click to enlarge:

World WAter Short Map 033016 uci_news_image_download

(UC Irvine/NASA)

The researchers found that 13 basins around the world — fully one-third of the total — appeared to be in serious trouble.

Eight aquifer systems could be categorized as “overstressed”: that is, there’s hardly any natural recharge to offset the water being consumed. In the direst state was the Arabian aquifer system beneath Saudi Arabia and Yemen, which provides water for 60 million people and is being depleted by irrigation for agriculture. Also in bad shape were the Indus Basin that straddles India and Pakistan and the Murzuq-Djado Basin in Africa.

Another five aquifer systems were categorized as “extremely” or “highly” stressed — they’re being replenished by some rainwater, but not nearly enough to offset withdrawals. That list includes the aquifers underneath California’s Central Valley. During California’s recent brutal, five-year drought, many farmers compensated for the lack of surface water by pumping groundwater at increasing rates. (There are few regulations around this, though California’s legislature recently passed laws that will gradually regulate groundwater withdrawals.)

The result? The basins beneath the Central Valley are being depleted, and the ground is actually sinking, which in turn means these aquifers will be able to store less water in the future. Farmers are losing a crucial buffer against both this drought, if it persists, and future droughts.

The big question: How soon until these aquifers run dry?

Here’s the other troubling bit: It’s unclear exactly when some of these stressed aquifers might be completely depleted — no one knows for sure how much water they actually contain.

In a companion paper in Water Resources Research, the researchers took stock of how little we know about these basins. In the highly stressed Northwest Sahara Aquifer System, for instance, estimates of when the system will be fully drained run anywhere from 10 years to 21,000 years. In order to get better measurements, researchers would have to drill down through many rock layers to measure how much water is there — a difficult task, but not impossible.

“We don’t actually know how much is stored in each of these aquifers. Estimates of remaining storage might vary from decades to millennia,” said Alexandra Richey, a graduate student at UC Irvine and lead author on both papers, in a press release. “In a water-scarce society, we can no longer tolerate this level of uncertainty, especially since groundwater is disappearing so rapidly.”

The researchers note that we should figure this out if we want to manage these aquifers properly — and make sure they last for many years to come. Hundreds of millions of people now rely on aquifers that are rapidly being depleted. And once they’re gone, they can’t easily be refilled.

Further reading

— Saudi Arabia squandered its groundwater and agriculture collapsed. The rest of the world should take note.

Nanoposres Seawater id41830

The right blend of polymers enables rapid and molecule-selective filtering of tiny particles from water.

A method of fabricating polymer membranes with nanometer-scale holes that overcomes some practical challenges has been demonstrated by KAUST researchers.

Porous membranes can filter pollutants from a liquid, and the smaller the holes, the finer the particles the membrane can remove. The KAUST team developed a block copolymer membrane with pores as small as 1.5 nanometers but with increased water flux, the volume processed per hour by a membrane of a certain area.

A nanofilter needs to be efficient at rejecting specific molecules, be producible on a large scale, filter liquid quickly and be resistant to fouling or the build-up of removed micropollutants on the surface.

Block copolymers have emerged as a viable material for this application. Their characteristics allow them to self-assemble into regular patterns that enable the creation of nanoporous materials with pores as small as 10 nanometers.

However, reducing the size further to three nanometers has only been possible by post-treating the membrane (depositing gold, for example2). Moreover, smaller holes usually reduce the water flux.

Klaus-Viktor Peinemann from the KAUST Advanced Membranes & Porous Materials Center and Suzana Nunes from the KAUST Biological and Environmental Science and Engineering Division formed a multidisciplinary team to find a solution.

“We mixed two block copolymers in a casting solution, tuning the process by choosing the right copolymer systems, solvents, casting conditions,” explained Haizhou Yu, a postdoctoral fellow in Peinemann’s group. This approach is an improvement on alternatives because it doesn’t require material post-treatment.

Peinemann and colleagues blended polystyrene-b-poly(acrylic acid) and polystyrene-b-poly(4-vinylpyridine) in a ratio of six to one. This created a sponge-like layer with a 60 nanometer film on top. Material analysis showed that nanoscale pores formed spontaneously without the need for direct patterning1.

The researchers used their nanofiltration material to filter the biological molecule protoporphyrin IX from water. The filter simultaneously allowed another molecule, lysine, to pass through, demonstrating its molecular selectivity. The researchers were able to filter 540 liters per hour for every square meter of membrane, which is approximately 10 times faster than commercial nanofiltration membranes.

The groups teamed up with Victor Calo from the University’s Physical Science and Engineering Division to develop computer models to understand the mechanism of pore formation. They showed that the simultaneous decrease in pore size and increase in flux was possible because, while the pores are smaller, the pore density in the block copolymer is higher.

“In the future, we hope to optimize membranes for protein separation and other applications by changing the copolymer composition, synthesizing new polymers and mixing with additives,” said Nunes.


Story Source:

The above post is reprinted from materials provided by KAUST – King Abdullah University of Science and Technology. Note: Materials may be edited for content and length.


Journal References:

  1. Yu, H., Qiu, X., Moreno, N., Ma, Z., Calo, V. M., Nunes, S. P. & Peinemann, K.-V. Self-assembled asymmetric block copolymer membranes: Bridging the gap from ultra- to nanofiltration. Angewandte Chemie International Edition, December 2015
  2. Haizhou Yu, Xiaoyan Qiu, Suzana P. Nunes, Klaus-Viktor Peinemann. Self-Assembled Isoporous Block Copolymer Membranes with Tuned Pore Sizes. Angewandte Chemie International Edition, 2014; 53 (38): 10072 DOI: 10.1002/anie.201404491

Penn St Water M id40923 A synthetic membrane that self assembles and is easily produced may lead to better gas separation, water purification, drug delivery and DNA recognition, according to an international team of researchers. This biomimetic membrane is composed of lipids — fat molecules — and protein-appended molecules that form water channels that transfer water at the rate of natural membranes, and self-assembles into 2-dimensional structures with parallel channels.

“Nature does things very efficiently and transport proteins are amazing machines present in biological membranes,” said Manish Kumar, assistant professor of chemical engineering, Penn State. “They have functions that are hard to replicate in synthetic systems.”
The researchers developed a second-generation synthetic water channel that improves on earlier attempts to mimic aquaporins – natural water channel proteins — by being more stable and easier to manufacture. The peptide-appended pillar[5]arenes (PAP) are also more easily produced and aligned than carbon nanotubes, another material under investigation for membrane separation. Kumar and co-authors report their development in a recent issue of the Proceedings of the National Academy of Science (“Highly permeable artificial water channels that can self-assemble into two-dimensional arrays”).

 

Penn St Water M id40923

An artificial analogue of the water channel protein, aquaporin, was shown to have permeabilities approaching that of aquaporins and carbon nanotubes. They also arrange in tight two dimensional arrays. (Image: Karl Decker / University of Illinois at Urbana-Champaign, and Yuexiao Shen / Penn State)

“We were surprised to see transport rates approaching the ‘holy grail’ number of a billion water molecules per channel per second,” said Kumar. “We also found that these artificial channels like to associate with each other in a membrane to make 2-dimentional arrays with a very high pore density.”
The researchers consider that the PAP membranes are an order of magnitude better than the first-generation artificial water channels reported to date. The propensity for these channels to automatically form densely packed arrays leads to a variety of engineering applications.
“The most obvious use of these channels is perhaps to make highly efficient water purification membranes,” said Kumar.
Source: Penn State

Graphene Water 071115 RTRDE3R1-628x330 This post is part of a series examining the connections between nanotechnology and the top 10 trends facing the world, as described in the Outlook on the Global Agenda 2015. All authors are members of the Global Agenda Council on Nanotechnology.

In the 2015 World Economic Forum’s Global Risks Report survey participants ranked Water Crises as the biggest of all risks, higher than Weapons of Mass Destruction, Interstate Conflict and the Spread of Infectious Diseases (pandemics). Our dependence on the availability of fresh water is well documented, and the United Nations World Water Development Report 2015 highlights a 40% global shortfall between forecast water demand and available supply within the next fifteen years. Agriculture accounts for much of the demand, up to 90% in most of the world’s least-developed countries, and there is a clear relationship between water availability, health, food production and the potential for civil unrest or interstate conflict.

The looming crisis is not limited to water for drinking or agriculture. Heavy metals from urban pollution are finding their way into the aquatic ecosystem, as are drug residues and nitrates from fertilizer use that can result in massive algal blooms. To date, there has been little to stop this accretion of pollutants and in closed systems such as lakes these pollutants are being concentrated with unknown long term effects.

While current solutions such as reverse osmosis exist, and are widely used in the water desalination of seawater, the water they produce is expensive. This is because high pressures are required to force the waster through a membrane and maintaining this pressure requires around 2kWh for every cubic meter of water. While this is less of an issue for countries with cheap energy, it puts the technology beyond the reach of most of the world’s population.

Any new solution for water issues needs to be able to demonstrate precise control over pore sizes, be highly resistant to fouling and significantly reduce energy use, a mere 10% won’t make a difference. Nanotechnology has long been seen as a potential solution. Our ability to manipulate matter on the scale of a few atoms allows scientists to work at the same scale as mot of the materials that need to be removed from water — salts, metal ions, emulsified oil droplets or nitrates. In theory then it should be a simple matter of creating a structure with the correct size nanoscale pores and building a better filter.

Ten years ago, following discussions with former Israeli Prime Minister Shimon Peres, I organised a conference in Amsterdam called Nanowater to look at how nanotechnology could address global water issues. While the meeting raised many interesting points, and many companies proposed potential solutions, there was little subsequent progress.

Rather than a simple mix of one or two contaminants, most real world water can contain hundreds of different materials, and pollutants like heavy metals may be in the form of metal ions that can be removed, but are equally likely to be bound to other larger pieces of organic matter which cannot be simply filtered through nanopores.  In fact the biggest obstacle to using nanotechnology in water treatment is the simple fact that small holes are easily blocked, and susceptibility to fouling means that

Fortunately some recent developments in the ‘wonder material’ graphene may change the economics of water. One of the major challenges in the commercialisation of graphene is the ability to create large areas of defect-free material that would be suitable for displays or electronics, and this is a major research topic in Europe where the European Commission is funding graphene research to the tune of a billion euros. Simultaneously there are vast efforts inside organisations such as Samsung and IBM. While defects are not wanted for electronic applications, recent research by Nobel Prize winner Andrei Geim and Rahul Nair has indicated that in graphene oxide they result in a barrier that is highly impermeable to everything except water vapour. However, precisely controlling the pore size can be difficult.

Another approach taken by researchers at MIT involves bombarding graphene sheets with beams of gallium ions to create weak spots and then etching them to create more precisely controlled pore sizes. A similar approach to water transport through defects has been taken by researchers at Penn State University.

While all of the above show that graphene has prospects for use as a filter medium, what about the usual limiting issue, membrane fouling? Fortunately another property of graphene is that it can be hydrophilic, it repels water, and protein absorption has been reported to have been reduced by over 70% in bioreactor tests. Many other groups are working on the use of graphene oxide and graphene nanoplatelets as an anti-fouling coating.

While the graphene applications discussed so far address one or two of the issues, it seems that thin films of graphene oxide may be able to provide the whole solution. Miao Yu and his team at the University of South Carolina have fabricated membranes that deliver very high flux and do not foul. Fabrication is handled by adding a thin layer of graphene to an existing membrane, as distinct from creating a membrane out of graphene, something which is far harder to do and almost impossible to scale up.

Getting a high flux is crucial to desalination applications where up to 50% of water costs are caused by pressurising water for transmission through a membrane.  Performance tests reveal around 100% membrane recovery simply by surface water flushing and pure water flux rates (the amount of water that the membrane transmits) are two orders of magnitude higher than conventional membranes. This is the result of the spacing between the graphene plates that allows the passage of water molecules via nanoscale capillary action but not contaminants.Graphene Desalinate 0422 water

Non-fouling is crucial for all applications, and especially in oil/water separation as most of what is pumped out of oil wells is water mixed with a little oil.

According to G2O Water, the UK company commercialising Yu’s technology, the increased flux rates are expected to translate directly into energy savings of up to 90% for seawater desalination. Energy savings on that scale have the potential to change the economics of desalination with smaller plants powered by renewable energy and addressing community needs replacing the power hungry desalination behemoths currently under construction such as the Carlsbad Project. This opens the possibility of low-cost water in areas of the world where desalination is currently too expensive or there is insufficient demand to justify large scale infrastructure.

While more work is required to build a robust and cost-effective filtration system, the new ability to align sheets of graphene so that water but nothing else is transmitted may be the simple game-changer that allows the world to finally address the growing water crisis.

Author: Tim Harper is Chief Executive Officer of G2O Water.

Image: The colors of Fall can be seen reflected in a waterfall along the Blackberry River in Canaan, Connecticut REUTERS/Jessica Rinaldi

UN World Water Crisis 070615 1386965848_png_CROP_promovar-mediumlarge Nearly 800 million people worldwide don’t have access to safe drinking water, and some 2.5 billion people live in precariously unsanitary conditions, according to the Centers for Disease Control and Prevention.

Together, unsafe drinking water and the inadequate supply of water for hygiene purposes contribute to almost 90% of all deaths from diarrheal diseases — and effective water sanitation interventions are still challenging scientists and engineers.

A new study published in Nature Nanotechnology proposes a novel nanotechnology-based strategy to improve water filtration. The research project involves the minute vibrations of carbon nanotubes called “phonons,” which greatly enhance the diffusion of water through sanitation filters. The project was the joint effort of a Tsinghua University-Tel Aviv University research team and was led by Prof. Quanshui Zheng of the Tsinghua Center for Nano and Micro Mechanics and Prof. Michael Urbakh of the TAU School of Chemistry, both of the TAU-Tsinghua XIN Center, in collaboration with Prof. Francois Grey of the University of Geneva.

Shake, rattle, and roll

“We’ve discovered that very small vibrations help materials, whether wet or dry, slide more smoothly past each other,” said Prof. Urbakh. “Through phonon oscillations — vibrations of water-carrying nanotubes — water transport can be enhanced, and sanitation and desalination improved. Water filtration systems require a lot of energy due to friction at the nano-level. With these oscillations, however, we witnessed three times the efficiency of water transport, and, of course, a great deal of energy saved.”

The research team managed to demonstrate how, under the right conditions, such vibrations produce a 300% improvement in the rate of water diffusion by using computers to simulate the flow of water molecules flowing through nanotubes. The results have important implications for desalination processes and energy conservation, e.g. improving the energy efficiency for desalination using reverse osmosis membranes with pores at the nanoscale level, or energy conservation, e.g. membranes with boron nitride nanotubes.

Crowdsourcing the solution

The project, initiated by IBM’s World Community Grid, was an experiment in crowdsourced computing — carried out by over 150,000 volunteers who contributed their own computing power to the research.

“Our project won the privilege of using IBM’s world community grid, an open platform of users from all around the world, to run our program and obtain precise results,” said Prof. Urbakh. “This was the first project of this kind in Israel, and we could never have managed with just four students in the lab. We would have required the equivalent of nearly 40,000 years of processing power on a single computer. Instead we had the benefit of some 150,000 computing volunteers from all around the world, who downloaded and ran the project on their laptops and desktop computers.

“Crowdsourced computing is playing an increasingly major role in scientific breakthroughs,” Prof. Urbakh continued. “As our research shows, the range of questions that can benefit from public participation is growing all the time.”

The computer simulations were designed by Ming Ma, who graduated from Tsinghua University and is doing his postdoctoral research in Prof. Urbakh’s group at TAU. Ming catalyzed the international collaboration. “The students from Tsinghua are remarkable. The project represents the very positive cooperation between the two universities, which is taking place at XIN and because of XIN,” said Prof. Urbakh.

Other partners in this international project include researchers at the London Centre for Nanotechnology of University College London; the University of Geneva; the University of Sydney and Monash University in Australia; and the Xi’an Jiaotong University in China. The researchers are currently in discussions with companies interested in harnessing the oscillation know-how for various commercial projects.


Story Source:

The above post is reprinted from materials provided by American Friends of Tel Aviv University. Note: Materials may be edited for content and length.

GNT Thumbnail Alt 3 2015-page-001“Imagine getting fire-hose volumes and velocities out of your garden hose. Nanotechnology could fundamentally change the economics of desalination.”

Nearly three-quarters of the Earth’s surface is covered by water, but according to the United Nations, more than 97 percent of it is saltwater unsuited for human consumption or agriculture.

The United Nations Population Fund reports that by 2025 two-thirds of the world’s projected population of 7.9 billion may live in areas where access to safe water is limited. “Every time we add a person, it’s not just the water that person consumes but also the additional water for agriculture and industry that you have to use,” says Earl Jones, director of water-scarcity solutions in General Electric Co.’s (GE) Water & Process Technologies unit.

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The removal of salt from seawater is an increasingly cost effective answer to the earth’s growing clean-water needs. By 2025, two-thirds of the world’s population may live in areas where access to safe water is limited, reports the U.N.

The removal of salt from water is emerging as one of the best solutions to the world’s water problem, analysts say. According to GOLDMAN SACH S Group Inc. (GS), desalination is a $5 billion global market, with growth of 10 percent to 15 percent a year. Water Desalination Report, a trade journal, reports that more than 12,000 desalination plants are operating World-wide, with 53 percent of the world’s desalination capacity in the Middle East.

“Today, the global capacity is about 40 million cubic meters of desalinated water per day,” says Antoine Frérot, CEO of Veolia Water, the water division of Veolia Environnement (VE). “By 2015, it will be around 70 million cubic meters per day.” Improvements in two technologies are making desalination more cost-efficient, say the experts:

The thermal process, which couples a thermal desalination plant with a power plant to provide the energy, involves evaporating water to remove salt.

Reverse osmosis, the other process, uses semipermeable membranes. About 84 percent of the world’s thermal desalination capacity, which requires more energy than reverse-osmosis facilities, is located in the Middle East, according to Water Desalination Report.  

Ashkelon Desal onearth_creattica_desalination-process 2

“We have one huge advantage in the Gulf,” says Phil Cox, CEO of International Power PLC (IPR), which builds, owns and operates thermal desalination plants in that region. “The price of natural gas is extremely low here compared with the rest of the world,” he adds. Outside the Middle East, reverse osmosis is the less expensive alternative, says Jean-Louis Chaussade, CEO of Suez Environment, a unit of Suez SA (SZE). “At our biggest reverse osmosis plants, we operate at roughly 60 cents per cubic meter of use,” says Chaussade.

Aside from GE, International Power, Suez and Veolia, other companies that construct, own and/or operate desalination systems worldwide include The AE S Corp. (AES), Crane Co.’s (CR) Crane Environmental, Siemens AG’s (SI) Power Generation unit and ITT Corp. (ITT). ABB Ltd . (ABB) provides electrical systems for desalination plants, and Met-Pro Corp.’s (MPR) Fybroc division manufactures pumps used in reverse-osmosis plants.

The motivation is there to solve the world’s water needs, the companies say. “According to the U.N., the No. 1 cause of death and illness in developing nations is waterborne diseases,” says GE’s Jones. “We have the technology to fix these problems. It’s very easy to get motivated because of the great opportunity to do good.”  

The Scale Effect  

The world’s largest reverse-osmosis plant in terms of production is Veolia Water’s Ashkelon Seawater Desalination Plant (see illustration) south of Tel Aviv, which has a daily capacity of 320,000 cubic meters per day, according to the company. The plant produces enough water to meet the needs of 15 percent of Israeli households, Veolia reports. “There is a scale effect,” says Veolia Water CEO Antoine Frérot. “At a small desalination plant, the price of water is around $2 per cubic meter. In Ashkelon, the price is 55 cents per cubic meter.”

Other big projects are in the works: General Electric Co.’s (GE) Infrastructure, Water & Process Technologies reports that it plans to open Africa’s largest seawater desalination project in Algiers, Algeria. An international consortium led by Siemens’ Power Generation unit says it plans to build the world’s largest independent water and power project in Riyadh, Saudi Arabia. Uwe Rokossa, Siemens projects sales director for new plants and services in the Middle East predicts: “We will see a continuation of big power and desalination projects.”

Steam Power and Hybrids

Thermal desalination requires steam to boil seawater, GE explains. According to GE’s Earl Jones, the most widely used thermal process is called multistage flash, which heats seawater in a brine tank, immediately converting it to steam. The resulting salt-free steam is captured, cooled and condensed, creating desalinated water, Jones reports. Since only some of the seawater is converted to steam, the process is repeated multiple times in different receptacles, each time using lower atmospheric pressures. The hybrid approach, which combines thermal and reverse-osmosis processes, is an emerging technology, according to Suez Environment, which provides the reverse-osmosis part of the first-ever hybrid facility in the United Arab Emirates. Having both techniques in one plant allows for flexibility, the company says. Suez Environment reports that when demand for electricity from the thermal side’s power plant is low, priority can be given to the less-energy-intensive reverse-osmosis process.

Another form of the hybrid approach involves having a mixture of different membranes inside a reverse-osmosis pressure vessel, says Lance Johnson, senior sales and marketing manager for Dow Water Solutions. “As the water moves down the vessel, the salt concentration increases. At the tail end, where the salinity is highest, you’d have a lower-pressure membrane than at the front end to boost productivity.

Emerging “Nano-Materials” and Membranes

Mixing high and low pressure membranes in a pressure vessel can lower cost.” Applying nanotechnology to membrane science is another promising avenue, according to GE’s Jones, who notes that membranes made out of nanotubes can process water faster than older methods. “Imagine getting fire-hose volumes and velocities out of your garden hose. Nanotechnology could fundamentally change the economics of desalination.”        

Graphene Nano Membrane 071615

Read More:

Oak Ridge 1 070615 graphene-desalinate-0422-waterOakridge National Laboratory: Using New Graphene Technology to Desalinate Water

 

 

Graphene Nano Membrane 071615 Nanoscale Desalination of Seawater Through Nanoporous Graphene

 

cARBON nANOTUBE wrappingcarbCan Engineered Carbon Nanotubes Help to Avert Our Water Crisis?

Canada Water 061915 Summary

Editor’s Note: This is the 10th installment of an occasional series on water scarcity issues around the world that Stratfor will be building upon periodically.

 

 

Despite being “water rich,” Canada will experience increasing regional water stress as demographics and climate variability threaten the natural resources in the country’s prairie. Suggestions about the possibility of Canada exporting water will emerge sporadically, as they have in the past. But such plans are highly unlikely to come to fruition, both because public opinion opposes the commoditization of water and because the exporting water would not be profitable. While Canada will continue to protect its freshwater resources, it will not turn them into a traded commodity.

Analysis

Canada’s wealth of resources and comparatively small population allow the government to capitalize on the export of a number of goods, including oil, natural gas, fertilizer and wheat. But although Canada holds roughly 7 percent of the world’s renewable freshwater resources and less than 1 percent of the total global population, water is not poised to become another exported commodity — even as other areas of the world continue coping with water stress and water scarcity.

Canadian citizens generally view access to water as a basic human right and oppose attempts to sell it for profit. In addition, logistical difficulties and economic infeasibility — not only in Canada, but globally — ensure that bulk transfers of water across long distances will remain rare.

Canada’s Deceptive Abundance

The amount of renewable fresh water available to each Canadian citizen is more than 80,000 cubic meters per year. Even other countries that are not typically considered water stressed have far less water available per citizen. For example, the United Kingdom’s annual per capita water availability is just over 2,300 cubic meters per year, and the United States has just over 9,500 cubic meters per person.

However, Canada’s surfeit of water is greater on paper than it is in reality. The country’s water prices are among the lowest in the Organization for Economic Cooperation and Development, encouraging overuse of the resources. Moreover, as in the United States, Canada’s water is not equally distributed. The majority of Canada’s population lives in the southern part of the country, but 60 percent of the country’s renewable water drains to the north, so access to water resources is limited. In fact, some areas of Canada are already experiencing some degree of water stress.

The prairie provinces of Alberta, Manitoba and Saskatchewan are typically more arid than other parts of the country. An expansion of agricultural and industrial activity in the region, along with population increases in recent decades, has led to greater water stress in parts of these provinces, and the pressure is expected to increase in coming decades. Agricultural and extractive industrial activity can be expected to continue in the region even as existing resources dwindle. Glaciers that feed the headwaters of many of the major rivers in the region have shrunk by roughly 25 percent in the past 100 years. Increasing temperatures and more frequent droughts are predicted, likely further increasing the strain on the water supply.

 


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