Magnetic Nanoparticles ease Removal of ‘microcontaminants’ from Wastewater


efficientremMany wastewater treatment plants do not completely remove chemical substances from wastewater. Credit: Symbol image: Shutterstock

Microcontaminants place a considerable burden on our water courses, but removing them from wastewater requires considerable technical resources. Now, ETH researchers have developed an approach that allows the efficient removal of these problematic substances.

In our , we all use a multitude of chemical substances, including cosmetics, medications, contraceptive pills, plant fertilisers and detergents—all of which help to make our lives easier. However, the use of such products has an adverse effect on the environment, because many of them cannot be fully removed from wastewater at today’s treatment plants. As , they ultimately end up in the environment, where they place a burden on fauna and flora in our water courses.

As part of a revision of the Waters Protection Act, parliament therefore decided in 2014 to fit an additional purification stage to selected water treatment plants by 2040 with a view to removing microcontaminants. Although the funding for this has in principle been secured, the project presents a challenge for plant operators because it is only possible to remove the critical substances using complex procedures, which are typically based on ozone, activated carbon or light.

Nanoparticles aid degradation

Now, researchers at ETH Zurich’s Institute of Robotics and Intelligent Systems have developed an elegant approach that could allow these substances to be removed more easily. Using multiferroic , they have succeeded in inducing the decomposition of chemical residues in contaminated water. Here, the nanoparticles are not directly involved in the chemical reaction but rather act as a catalyst, speeding up the conversion of the substances into harmless compounds.

“Nanoparticles such as these are already used as a catalyst in  in numerous areas of industry,” explains Salvador Pané, who has played a key role in advancing this research in his capacity as Senior Scientist. “Now, we’ve managed to show that they can also be useful for wastewater purification.”

Efficient removal of problem substances
Based on the example of various organic pigments, such as those used in the textile industry, the researchers are able to demonstrate the effectiveness of their approach. Picture left before treatment, right after treatment. Credit: ETH Zurich / Fajer Mushtaq

An 80 percent reduction

For their experiments, the researchers used aqueous solutions containing trace quantities of five common medications. The experiments confirmed that the nanoparticles can reduce the concentration of these substances in water by at least 80 percent. Fajer Mushtaq, a doctoral student in the group, underlines the importance of these results: “These  also included two compounds that can’t be removed using the conventional ozone-based method.”

“Remarkably, we’re able to precisely tune the catalytic output of the nanoparticles using magnetic fields,” explains Xiangzhong Chen, a postdoc who also participated in the project. The particles have a cobalt ferrite core surrounded by a bismuth ferrite shell. If an external alternating magnetic field is applied, some regions of the particle surface adopt positive electric charges, while others become negatively charged. These charges lead to the formation of reactive oxygen species in water, which break down the organic pollutants into harmless compounds. The magnetic nanoparticles can then be easily removed from water using , says Chen.

Positive responses from industry

The researchers believe that the new approach is a promising one, citing its easier technical implementation than that of ozone-based , for example. “The wastewater industry is very interested in our findings,” says Pané.

However, it will be some time before the method can be applied in practice, as it has been investigated only in the laboratory so far. At any rate, Mushtaq says that approval has already been given for a BRIDGE project jointly funded by the Swiss National Science Foundation and Innosuisse with a view to support the method’s transfer into practical applications. In addition, plans are already in place to establish a spin-off company, in which the researchers intend to develop their idea to market maturity.


Explore further

Chemists suggest a new method to synthesise titanium nanoparticles for water purification


More information: Fajer Mushtaq et al. Magnetoelectrically Driven Catalytic Degradation of Organics, Advanced Materials (2019). DOI: 10.1002/adma.201901378

Journal information: Advanced Materials
Provided by ETH Zurich
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Hairy nano-cellulose provides green anti-scaling solution – More applications including drug delivery, antimicrobial agents, and fluorescent dyes for medical imaging – McGill University


hairynanotecCredit: McGill University

A new type of cellulose nanoparticle, invented by McGill University researchers, is at the heart of a more effective and less environmentally damaging solution to one of the biggest challenges facing water-based industries: preventing the buildup of scale.

Formed by the accumulation of sparingly soluble minerals, scale can seriously impair the operation of just about any equipment that conducts or stores water – from household appliances to industrial installations. Most of the anti-scaling agents currently in use are high in phosphorus derivatives, environmental pollutants that can have catastrophic consequences for aquatic ecosystems.

In a series of papers published in the Royal Society of Chemistry’s Materials Horizons and the American Chemical Society’s Applied Materials & Interfaces, a team of McGill chemists and chemical engineers describe how they have developed a phosphorus-free anti-scaling solution based on a nanotechnology breakthrough with an unusual name: hairy nanocellulose.

An unlikely candidate

Lead author Amir Sheikhi, now a postdoctoral fellow in the Department of Bioengineering at the University of California, Los Angeles, says despite its green credentials  was not an obvious place to look for a way to fight scale.

“Cellulose is the most abundant biopolymer in the world. It’s renewable and biodegradable. But it’s probably one of the least attractive options for an anti-scaling agent because it’s neutral, it has no charged functional groups,” he says.

While working as a postdoctoral fellow with McGill chemistry professor Ashok Kakkar, Sheikhi developed a number of macromolecular antiscalants that were more effective than products widely used in industry – but all of his discoveries were phosphonate-based. His desire to push his research further and find a phosphorus-free alternative led him to take a closer look at cellulose.

“Nanoengineered hairy cellulose turned out to work even better than the phosphonated molecules,” he says.

The breakthrough came when the research team succeeded in nanoengineering negatively charged carboxyl groups onto cellulose nanoparticles. The result was a particle that was no longer neutral, but instead carried charged functional groups capable of controlling the tendency of positively charged calcium ions to form scale.

Hirsute wonder particle a chance discovery

Previous attempts to functionalize cellulose in this way focused on two earlier forms of nanoparticle – cellulose nanofibrils and . But these efforts produced only a minimal amount of useful product. The difference this time was that the McGill team worked with hairy nanocellulose – a new nanoparticle first discovered in the laboratory of McGill chemistry professor Theo van de Ven.

Van de Ven, who also participated in the anti-scaling research, recalls the moment in 2011 when Han Yang, then a doctoral student in his lab, stumbled upon the new form of nanocellulose.

“He came into my office with a test tube that looked like it had water in it and he said, ‘Sir! My suspension has disappeared!'” van de Ven says with a grin.

“He had a white suspension of kraft fibres and it had turned transparent. When something is transparent, you know immediately it has either dissolved or turned nano. We performed a number of characterizations and we realized he had made a new form of nanocellulose.”

Extreme versatility

The secret to making hairy nanocellulose lies in cutting cellulose nanofibrils – which are made up of an alternating series of crystalline and amorphous regions – at precise locations to produce nanoparticles with amorphous regions sprouting from either end like so many unruly strands of hair.

“By breaking the nanofibrils up the way we do, you get all these cellulose chains sticking out which are accessible to chemicals,” van de Ven explains. “That’s why our nanocellulose can be functionalized to a far greater extent than other kinds.”

Given the chemical versatility of hairy nanocellulose, the research team sees strong potential for applications beyond anti-scaling, including drug delivery, antimicrobial agents, and fluorescent dyes for medical imaging.

“We can link just about any molecule you can think of to hairy ,” van de Ven says.

 Explore further: Ready-to-use recipe for turning plant waste into gasoline

More information: Amir Sheikhi et al. Overcoming Interfacial Scaling Using Engineered Nanocelluloses: A QCM-D Study, ACS Applied Materials & Interfaces (2018). DOI: 10.1021/acsami.8b07435

Amir Sheikhi et al. Nanoengineering colloidal and polymeric celluloses for threshold scale inhibition: towards universal biomass-based crystal modification, Materials Horizons (2018). DOI: 10.1039/C7MH00823F

 

Rice University: NEWT (Nano Enabled Water Treatment) Reusable water-treatment particles effectively eliminate BPA


Rice U reusablewate water
Rice University researchers have enhanced micron-sized titanium dioxide particles to trap and destroy BPA, a water contaminant with health implications. Cyclodextrin molecules on the surface trap BPA, which is then degraded by reactive …more

Rice University scientists have developed something akin to the Venus’ flytrap of particles for water remediation.

The research is detailed in the American Chemical Society journal Environmental Science & Technology.

BPA is commonly used to coat the insides of food cans, bottle tops and  supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.

The good news is that reactive oxygen species (ROS) – in this case, hydroxyl radicals – are bad news for BPA. Inexpensive titanium dioxide releases ROS when triggered by ultraviolet light. But because oxi-dating molecules fade quickly, BPA has to be close enough to attack.

That’s where the trap comes in.

Close up, the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Rice researchers to anchor cyclodextrin molecules.

Reusable water-treatment particles effectively eliminate BPA
“Petals” of a titanium dioxide sphere enhanced with cyclodextrin as seen under a scanning electron microscope. When triggered by ultraviolet light, the spheres created at Rice University are effective at removing bisphenol A contaminants from water. Credit: Alvarez Lab

Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. BPA is also hydrophobic and naturally attracted to the cavity. Once trapped, ROS produced by the spheres degrades BPA into harmless chemicals.

In the lab, the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.

0629_NEWT-log-lg-310x310The work fits into technologies developed by the Rice-based and National Science Foundation-supported Center for Nanotechnology-Enabled Water Treatment because the spheres self-assemble from titanium dioxide nanosheets.

“Most of the processes reported in the literature involve nanoparticles,” said Rice graduate student and lead author Danning Zhang. “The size of the particles is less than 100 nanometers. Because of their very small size, they’re very difficult to recover from suspension in water.”

The Rice particles are much larger. Where a 100-nanometer particle is 1,000 times smaller than a human hair, the enhanced  is between 3 and 5 microns, only about 20 times smaller than the same hair. “That means we can use low-pressure microfiltration with a membrane to get these particles back for reuse,” Zhang said. “It saves a lot of energy.”
Reusable water-treatment particles effectively eliminate BPA
Rice graduate student Danning Zhang, who led the development of a particle that attracts and degrades contaminants in water, checks a sample in a Rice environmental lab. Credit: Jeff Fitlow

Because ROS also wears down cyclodextrin, the spheres begin to lose their trapping ability after about 400 hours of continued ultraviolet exposure, Zhang said. But once recovered, they can be easily recharged.

“This new material helps overcome two significant technological barriers for photocatalytic water treatment,” Alvarez said. “First, it enhances treatment efficiency by minimizing scavenging of ROS by non-target constituents in water. Here, the ROS are mainly used to destroy BPA.

“Second, it enables low-cost separation and reuse of the catalyst, contributing to lower treatment cost,” he said. “This is an example of how advanced materials can help convert academic hypes into feasible processes that enhance water security.”

 Explore further: Mat baits, hooks and destroys pollutants in water

More information: Danning Zhang et al. Easily-recoverable, micron-sized TiO2 hierarchical spheres decorated with cyclodextrin for enhanced photocatalytic degradation of organic micropollutants, Environmental Science & Technology (2018). DOI: 10.1021/acs.est.8b04301

 

MIT: World Water and Food Security Lab Receives $750K in Commercialization Awards


mit-WAter and Food Security 081916 karnik-lab-xylem_0

Membrane structures in plant xylem from different species are being investigated for use in water filtration. Image: Karnik Lab

Four new projects and one renewal receive $150,000 in funding for 2016-2017.

The Abdul Latif Jameel World Water and Food Security Lab (J-WAFS) has announced four new grant recipients in its J-WAFS Solutions program. J-WAFS Solutions is sponsored by Abdul Latif Jameel Community Initiatives, and provides commercialization grants to help develop products and services that will have a significant impact on water and food security, with related economic and societal benefits.

The program, managed by the MIT Deshpande Center for Technological Innovation, is in its second year. Like direct Deshpande grants, the goal of the funding is to advance a technology to the point where it can attract customer interest and investments to commercialize a product and launch a spinout company, and/or to license the technology to an existing organization. Funds support work to refine and enhance an innovation, systematically explore potential markets, and assess commercial viability, whereby the technology and market risks are sufficiently reduced.

The four new grants go to faculty in the departments of Chemical Engineering, Chemistry, and Mechanical Engineering. John H. Lienhard V, director of J-WAFS and the Abdul Latif Jameel World Water and Food Security Professor, says that MIT faculty continue to devise innovative technologies that are applicable to a range of challenges in the food and water sectors:

“Commercializing effective technologies with sound business models is one of MIT’s most effective mechanisms to have a positive impact on the world,” he says. “The J-WAFS Solutions program is helping not only to stimulate creative problem solving, but also to support entrepreneurial faculty and students who are motivated by problems of global importance.”

Following on prior J-WAFS seed funding, Alan Hatton, the Ralph Landau Professor of Chemical Engineering Practice, has been awarded a commercialization grant for the development of an affordable and robust purification technology. Seeing a need for separation technologies that can be applied to water purification needs in a range of contexts — from point-of-source treatment to remote in-situ purification devices to large-scale, centralized wastewater treatment facilities — the lab has been developing electrochemically-mediated adsorptive processes for water treatment. J‑WAFS Solutions funding will support the development of a demonstration unit and exploration of commercial application opportunities.

A new project led by Rohit Karnik, associate professor in the Department of Mechanical Engineering, and co-PI Amy Smith, senior lecturer in the Department of Mechanical Engineering and co-director of D-Lab, takes avery different approach to water purification. Addressing the largely unmet need to provide safe and affordable drinking water to very low-income groups, Karnik is developing low-cost water filters that exploit the natural filtration capabilities of xylem tissue in wood. Particularly in regions lacking access to piped water supply systems, microbial contamination is a major threat to health. With J-WAFS Solutions funding, Karnik’s lab will work with Amy Smith to validate filtration performance in the lab and in the field, while also assessing the usability, desirability, and affordability of low-cost filters and devising a strategy for local manufacture and commercialization.

Gang Chen, the Carl Richard Soderberg Professor in Power Engineering and head of the Department of Mechanical Engineering, was funded for his proposal on “Floating, Heat Localizing Solar Receivers for Distributed Desalination.” The lab’s invention is a wavelength-selective, insulating, solar powered still (WISPS) tarp structure that can blanket ocean, lake, and pond surfaces to generate freshwater onsite. The project addresses the challenges associated with scalability, cost, and water safety associated with seawater desalination by capitalizing on a recent innovation by Chen that achieves high evaporation rates and high efficiency by localizing high temperatures to the water surface.

The fourth funded project addresses the need for simple and rapid detection of pathogenic bacteria in food and water samples in order to prevent widespread infection, illness, and even death. Using a carbohydrate array detection scheme based on specific binding interactions of bacteria with carbohydrates, Timothy Swager, the John D. MacArthur Professor of Chemistry, and Alexander M. Klibanov, Novartis Professor in Chemistry and Bioengineering, are developing a system that will be able to simultaneously detect multiple types of pathogenic bacterial strains. The project will focus initially on the occurrence of food poisoning from ground beef — a common problem because of the prevalence of E. coli contamination in beef and dairy cattle and because bacteria that may only be on the surface and readily killed by cooking become dispersed throughout the meat during the grinding process.

A one-year renewal grant was awarded for another project that is pursuing point-of use identification of contaminants in drinking water and food through a different technology. Jointly led by Professor Michael S. Strano of the Department of Chemical Engineering and Professor Anthony Sinskey of the Department of Biology, this interdisciplinary project is leveraging new MIT nanotechnology to develop a single integrated platform that can address all important food and water contaminants — including bacterial pathogens, heavy metals, and allergens — in a low cost, widely deployable nanosensor array.

Renee J. Robins, executive director of J-WAFS, noted that the new projects span various aspects of ensuring a safe supply of water and food:

“Whether the issue is clean water for a rural village in India or enjoying a juicy hamburger cooked on the grill without fear of food poisoning, MIT researchers are developing technologies that will greatly improve people’s ability to have clean water and safe food at their ready disposal,” she says.

Researchers Create Unique Hybrid Nanomaterials to Transform Dirty Water into Drinkable Water


Graphene Hybrid Water072916 NewsImage_34896An artist’s rendering of nanoparticle biofoam developed by engineers at Washington University in St. Louis. The biofoam makes it possible to clean water quickly and efficiently using nanocellulose and graphene oxide. (Photo credit: Washington University in St. Louis)

Recently, a team of researchers from Washington University in St. Louis have discovered a method to use graphene oxide sheets to convert dirty water into drinking water. This could easily become a worldwide game-changer.

“We hope that for countries where there is ample sunlight, such as India, you’ll be able to take some dirty water, evaporate it using our material, and collect fresh water,” said Srikanth Singamaneni, associate professor of mechanical engineering and materials science at the School of Engineering & Applied Science.

The new method integrates graphene oxide and bacteria-produced cellulose to create a bi-layered biofoam. A paper explaining the research can be found online in Advanced Materials.

The process is extremely simple. The beauty is that the nanoscale cellulose fiber network produced by bacteria has excellent ability move the water from the bulk to the evaporative surface while minimizing the heat coming down, and the entire thing is produced in one shot. The design of the material is novel here. You have a bi-layered structure with light-absorbing graphene oxide filled nanocellulose at the top and pristine nanocellulose at the bottom.

When you suspend this entire thing on water, the water is actually able to reach the top surface where evaporation happens. Light radiates on top of it, and it converts into heat because of the graphene oxide — but the heat dissipation to the bulk water underneath is minimized by the pristine nanocellulose layer. You don’t want to waste the heat; you want to confine the heat to the top layer where the evaporation is actually happening.

Srikanth Singamaneni, Associate Professor, Washington University

The bottom of the bi-layered biofoam has the cellulose, which acts as a sponge, sucking water up to the graphene oxide where fast evaporation occurs. The resulting fresh water found at the top of the sheet can be effortlessly collected.

The method used to form the bi-layered biofoam is also new.

The graphene oxide flakes are embedded into the layers of nanocellulose fibers, which are formed by the bacteria. Using the same method used by an oyster to make a pearl, the bacteria create these layers.

While we are culturing the bacteria for the cellulose, we added the graphene oxide flakes into the medium itself. The graphene oxide becomes embedded as the bacteria produce the cellulose. At a certain point along the process, we stop, remove the medium with the graphene oxide and reintroduce fresh medium. That produces the next layer of our foam. The interface is very strong; mechanically, it is quite robust.

Qisheng Jiang, Graduate Student, Washington University

The new biofoam is also very light and cost-efficient to make, thus making it a feasible tool for desalination and water purification.

“Cellulose can be produced on a massive scale,” Singamaneni said, “and graphene oxide is extremely cheap — people can produce tons, truly tons, of it. Both materials going into this are highly scalable. So one can imagine making huge sheets of the biofoam.”

“The properties of this foam material that we synthesized has characteristics that enhances solar energy harvesting. Thus, it is more effective in cleaning up water,” said Pratim Biswas, the Lucy and Stanley Lopata Professor and chair of the Department of Energy, Environmental and Chemical Engineering.

“The synthesis process also allows addition of other nanostructured materials to the foam that will increase the rate of destruction of the bacteria and other contaminants, and make it safe to drink. We will also explore other applications for these novel structures.”

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NEWT (Nano Enabled Water Treatment) Nanoscale solutions to a very large problem


NEWT 040416 Westerhoff_Lab_1_f

ERCs produce both transformational technology and innovative-minded engineering graduates.
Credit and Larger Version

NSF-funded Nanosystems Engineering Research Center to enable deployment of mobile, efficient water treatment and desalination systems 

** NEWT is a joint designated collaboration between Rice University, ASU, UTEP and Yale University 

 

0629_NEWT-log-lg-310x310Water, water is everywhere, but we need more drops to drink.

The primary mission of the recently founded Nanotechnology Enabled Water Treatment (NEWT) Center, a consortium based at Rice University and led by environmental engineer Pedro Alvarez, is to produce more drinkable drops where they’re needed the most.

According to Alvarez, treated water is too often unavailable in parts of the world that cannot afford large treatment plants or miles of pipes to deliver it. Moreover, large-scale treatment and distribution uses a great deal of energy. “About 25 percent of the energy bill for a typical city is associated with the cost of moving water,” he said.

The center, funded by a five-year, $18.5 million National Science Foundation (NSF) award was founded to transform the economics of water treatment by using nanotechnology to develop compact, mobile, off-grid systems to provide clean water to millions of people around the world. A second goal is to make U.S. energy production more sustainable and cost-effective in regards to its water use.

NEWT is the first NSF Engineering Research Center (ERC) based in Houston. ERCs are interdisciplinary, multi-institutional centers that join academia, industry and government in partnership to produce both transformational technology and innovative-minded engineering graduates primed to lead the global economy. ERCs often become self-sustaining and typically leverage more than $40 million in federal and industry research funding during their first decade.

Water has long been a passion for Alvarez, who studies treatment and reuse, remediation strategies for contaminated aquifers and the water footprints of biofuels. His work also covers the environmental implications of using nanotechnology, and the transport — and eventual fate of — toxic chemicals in the environment. As NEWT director, he partners with researchers at Arizona State University (ASU), Yale University and the University of Texas at El Paso.

The consortium set as its first goal the development of modular water treatment systems that can deploy almost anywhere in the world. But Alvarez said the potential to make a significant impact is already expanding, with opportunities to address wastewater treatment at oil and gas drilling sites, nano-infused desalination in urban environments, and improved water treatment through more efficient filtration at existing plants.

Alvarez paused between classes recently to talk about the center’s plans.

Q. Where do you think NEWT’s greatest impact will be in 10 years?

A. It will be in drinking water, providing cleaner water to millions of people who now lack it. I think it’s going to be in developing small, portable units that will not only provide humanitarian water but also emergency response.

There will be other Flints. There will be other Elk River spills that will impact municipalities and water. I think we will be able to respond to those things.

We will probably have tremendous impact on desalination. Low-energy desalination will be one of our hallmarks, I believe. Of course, we will be very good also at treating some of the oil-and-gas water issues, but that’s a more difficult problem.

I expect we’ll also have high institutional impact because people may be more ready to consider unconventional water sources using portable systems that are easier to deploy. People are going to start considering more and more decentralized water-treatment approaches, especially as new cities and neighborhoods and developments evolve.

Q. What kind of sources will your technology be able to treat?

A. Briny ground water, for example, could be a source of drinking water in areas experiencing drought. Or in coastal areas. I think we will see more of that. We’ll see more harvesting of storm water, certainly, and for some uses, even greywater.

Those are the kinds of things our technologies will enable, but it’s not just about technology. It’s about the philosophy of changing to more sustainable, integratable water management, where we reuse more water, where we tap water that we thought was of too low quality but, as it turns out, is perfectly fine and safe and more economical for a sole intended use.

Q. In what directions are the initial projects headed?

A. I think the first thing we’re going to have out there is an adsorbent filter being developed by [NEWT deputy director] Paul Westerhoff at ASU. It’s a block of carbon with embedded nanoparticles. These particles adsorb — that is, they grab onto and hold — oxyanion contaminants like nitrate, arsenic and chromate, and effectively remove them from the water supply. [Oxyanions are negatively charged ions that contain oxygen.] It will be part of a drinking-water treatment unit.

Q. Would the technology apply to large water treatment plants?

A. Yes. Though we originally intended to carve a niche in the decentralized water treatment market, we do aspire to bigger things as our products, materials and processes gain momentum.

I am sure there will be a lot that can be used by the municipal water treatment community. It’s a more difficult industry to penetrate because it’s very conservative. You have to convince them that a technology is going to save them a lot of money and that they don’t have to change too much of the infrastructure or the configuration of the plant.

We have some very good ideas of things that will fit them. If they’re already using membranes for filtration, for example, our membranes may offer better rejection of contaminants and perhaps less susceptibility to being fouled, so they will last longer without having to be replaced. They won’t clog up as easily. They will not use as much energy.

Q. Why did you pursue hosting this NSF center?

A. I think that we as scientists and as engineers, especially in developed countries, have a social debt toward many poor people who lack access to clean water because they are denied the right to a life consistent with their inalienable dignity.

The lack of clean water is a major hindrance to human capacity. It goes beyond public health: It’s directly tied to the need for economic development.

That is certainly one important factor in my passion to provide water to many. It’s related to the concept of world affirmation, the idea that the world can be a better place and we can do something about it. Providing clean water is one way to do it.

The other big incentive was to try to move towards energy self-sufficiency in the United States in a manner that is more cost-effective and more sustainable with regards to the water footprint.

A major challenge for our energy industry is that they need to operate and extract oil and gas in areas that are relatively dry and semi-arid, where water is scarce. And they need relatively large quantities of water to obtain this energy. To get a barrel of oil in Texas, you need about 10 barrels of water. To frack a well to get shale gas or shale oil, you may need up to 6 million gallons of water, again in areas where water is scarce.

Once it’s used, disposal of that water becomes a major challenge and a potentially serious source of pollution. So the solution to both scarcity and minimizing impact is to reuse this water. That’s one of the things we’re trying to do: develop systems that are small and easily deployed that can enable industrial wastewater reuse in remote areas.

Q. What can you do with nanoparticles that you couldn’t have done before?

A. We need to recognize that at the nanoscale, the properties of matter change. Some elements, such as gold, that are very inert can become hypercatalytic at that scale, and materials that are good insulators like carbon can become superconductors.

When you exploit these extraordinary size-dependent properties, it allows you to introduce multifunctionality at both the reactor and materials level. This combination of multifunctionality — for example, membranes that have self-cleaning and self-healing properties — with the nanotechnology-enabled ability to selectively remove pollutants allows you to have smaller reactors. These can treat even unconventional sources of water, difficult sources, that currently would require huge reactors and very large and complex treatment trains that are impossible to take to remote locations.

Making them smaller, multifunctional and modular brings you tremendous versatility to handle a wide variety of challenges in water purification. Nanotechnology allows us to do that. It’s essential to our vision of decentralized water treatment systems.

Q. You’re an environmental engineer who knows aquatic chemistry, and you rely on other kinds of engineers and scientists for different parts of the water systems.

A. Absolutely. This has to be a multidisciplinary collaborative effort to build this innovation ecosystem. We need people who know how to make materials and people who know how to characterize them, how to immobilize them, how to manipulate them — how to assess their reactivity and bioavailability and mobility, and eventually scale them up.

We want people who are good at designing and building reactors all the way to systems to think about the whole lifecycle, the techno-economic implications of these materials, to make sure they’re feasible and improve on current practices.

They have to do it in a way that’s sustainable and avoids unintended, undesirable consequences as well.

Alvarez is the George R. Brown Professor of Environmental Engineering in the Department of Civil and Environmental Engineering at Rice University.


Investigators

Pedro Alvarez
Menachem Elimelech
Naomi Halas
Qilin Li
Paul Westerhoff

Related Institutions/Organizations
William Marsh Rice University
Arizona State University
University of Texas-El Paso
Yale University

Locations
Arizona
Connecticut
Texas

Related Programs
Engineering Research Centers

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UC Berkeley: Nanotechnology Can Help Deliver Affordable, Clean Water with Graphene Membrane: Video


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Clean drinking water is essential for good health and disease prevention. But according to the World Health Organization, some 663 million people — one out of every 10 people in the world — do not have access to safe water. But science may soon help. As Faiza Elmasry tells us, researchers have developed nano-scaled membranes that could filter contaminants from water faster and more cheaply than current methods. Faith Lapidus narrates.

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KAUST:Nanoscale Polymer Membranes for ‘Selective’ Water Filtering


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

Nanotechnology Enabled Water Treatment or NEWT: Transforming the Economics of Water Treatment: Rice, ASU, Yale, UTEP win $18.5 Million NSF Engineering Research Center


LARGE_NEWTisometricNEWT Center will use nanotechnology to transform economics of water treatment A Rice University-led consortium of industry, university and government partners has been chosen to establish one of the National Science Foundation’s (NSF) prestigious Engineering Research Centers in Houston to develop compact, mobile, off-grid water-treatment systems that can provide clean water to millions of people who lack it and make U.S. energy production more sustainable and cost-effective.

Nanotechnology Enabled Water Treatment Systems, or NEWT, is Houston’s first NSF Engineering Research Center (ERC) and only the third in Texas in nearly 30 years. It is funded by a five-year, $18.5 million NSF grant that can be renewed for a potential term of 10 years. NEWT brings together experts from Rice, Arizona State University, Yale University and the University of Texas at El Paso (UTEP) to work with more than 30 partners: including Shell, Baker Hughes, UNESCO, U.S. Army Corps of Engineers and NASA.

ERCs are interdisciplinary, multi-institutional centers that join academia, industry and government in partnership to produce both transformational technology and innovative-minded engineering graduates who are primed to lead the global economy. ERCs often become self-sustaining and typically leverage more than $40 million in federal and industry research funding during their first decade.

“The importance of clean water to global health and economic development simply cannot be overstated,” said NEWT Director Pedro Alvarez, the grant’s principal investigator. “We envision using technology and advanced materials to provide clean water to millions of people who lack it and to enable energy production in the United States to be more cost-effective and more sustainable in regard to its water footprint.”

NEWT Center will use nanotechnology to transform water treatment: Video

Houston-area Congressman John Culberson, R-Texas, chair of the House Subcommittee on Commerce, Justice and Science, said, “Technology is a key enabler for the energy industry, and NEWT is ideally located at Rice, in the heart of the world’s energy capital, where it can partner with industry to ensure that the United States remains a leading energy producer.”

Alvarez, Rice’s George R. Brown Professor of Civil and Environmental Engineering and professor of chemistry, materials science and nanoengineering, said treated water is often unavailable in rural areas and low-resource communities that cannot afford large treatment plants or the miles of underground pipes to deliver water. Moreover, large-scale treatment and distribution uses a great deal of energy. “About 25 percent of the energy bill for a typical city is associated with the cost of moving water,” he said.

NEWT Deputy Director Paul Westerhoff said the new modular water-treatment systems, which will be small enough to fit in the back of a tractor-trailer, will use nanoengineered catalysts, membranes and light-activated materials to change the economics of water treatment.0629_NEWT-truck-lg-310x239

“NEWT’s vision goes well beyond today’s technology,” said Westerhoff, vice provost of academic research at ASU and co-principal investigator on the NSF grant. “We’ve set a path for transformative new technology that will move water treatment from a predominantly chemical treatment process to more efficient catalytic and physical processes that exploit solar energy and generate less waste.”

Co-principal investigator and NEWT Associate Director for Research Qilin Li, the leader of NEWT’s advanced treatment test beds at Rice, said the system’s technology will be useful in places where water and power infrastructure does not exist.

“The NEWT drinking water system will be able to produce drinking water from any source, including pond water, seawater and floodwater, using solar energy and even under cloudy conditions,” said Li, associate professor of civil and environmental engineering, chemical and biomolecular engineering, and of materials science and nanoengineering at Rice. “The modular treatment units will be easy to configure and reconfigure to meet desired water-quality levels. The system will include components that target suspended solids, microbes, dissolved contaminants and salts, and it will have the ability to treat a variety of industrial wastewater according to the industry’s need for discharge or reuse.”0629_NEWT-mod-lg-310x239

NEWT will focus on applications for humanitarian emergency response, rural water systems and wastewater treatment and reuse at remote sites, including both onshore and offshore drilling platforms for oil and gas exploration.

0629_NEWT-log-lg-310x310Yale’s Menachem “Meny” Elimelech, co-principal investigator and lead researcher for membrane processes, said NEWT’s innovative enabling technologies are founded on rigorous basic research into nanomaterials, membrane dynamics, photonics, scaling, paramagnetism and more.

“Our modular water-treatment systems will use a combination of component technologies,” said Elimelech, Yale’s Roberto C. Goizueta Professor of Environmental and Chemical Engineering. “For example, we expect to use high-permeability membranes that resist fouling; engineered nanomaterials that can be used for membrane surface self-cleaning and biofilm control; capacitive deionization to eliminate scaly mineral deposits; and reusable magnetic nanoparticles that can soak up pollutants like a sponge.”

UTEP’s Jorge Gardea-Torresdey, co-principal investigator and co-leader of NEWT’s safety and sustainability effort, said the rapid development of engineered nanomaterials has brought NEWT’s transformative vision within reach.

“Treating water using fewer chemicals and less energy is crucial in this day and age,” said Gardea-Torresdey, UTEP’s Dudley Professor of Chemistry and Environmental Science and Engineering. “The exceptional properties of engineered nanomaterials will enable us to do this safely and effectively.”

Alvarez said another significant research thrust in nanophotonics will be headed by Rice co-principal investigator Naomi Halas, the inventor of “solar steam” technology, and co-led by ASU’s Mary Laura Lind.

“More than half of the cost associated with desalination of water comes from energy,” said Halas, Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering. “We are working to develop several supporting technologies for NEWT, including nanophotonics-enabled direct solar membrane distillation for low-energy desalination.”

Mike Wong Lake%20ZurichRice’s Michael Wong, Yale’s Jaehong Kim and UTEP’s Dino Villagran will collaborate in efforts to develop novel multifunctional materials such as superior sorbents and catalysts, and Yale’s Julie Zimmerman will co-lead cross-cutting efforts in safety and sustainability. Rice’s Roland Smith will lead a comprehensive diversity program that aims to attract more women and underrepresented minority students and faculty, and Rice’s Brad Burke will head up innovation and commercialization efforts with private partners. Rice’s Rebecca Richards-Kortum will lead an innovative educational program that incorporates some of the “experiential learning” techniques she developed for the award-winning undergraduate research programs at Rice 360º: Institute for Global Health Technologies, and Rice’s Carolyn Nichol will lead the K-12 education efforts.

Alvarez said NEWT’s goal is to attract industry funding and become self-sufficient within 10 years. Toward that end, he said NEWT was careful to select industrial partners from every part of the water market, including equipment makers and vendors, system operators, industrial service firms and others.

NEWT is one of three new ERCs announced by the NSF today in Washington. They join 16 existing centers that are still receiving federal support, including Texas’ only other active ERC, the University of Texas at Austin’s NASCENT, as well as the other active center in which Rice is a partner, Princeton University’s MIRTHE.

0629_NEWT-Alvarez29-lg-310x465Alvarez credited Culberson and the Texas Railroad Commission for helping facilitate partnerships that were crucial for NEWT. He said the consortium’s bid to land the NSF grant was also made possible by seed funding from Rice’s Energy and Environment Initiative, a sweeping institutional initiative to engage Rice faculty from all disciplines in creating sustainable, transformative energy technologies.

“Rice’s Energy and Environment Initiative was instrumental in developing a competitive proposal, in facilitating a team-building effort and in facilitating contacts with industry to get the necessary buy-in for our vision,” Alvarez said.

Nanotechnology Enabled Water Treatment Program

LARGE_NEWTisometric

Using Platinum-nickel Nanoalloys and Microwaves for Catalytic Water Treatment


Water Treatment Catalyst Microwavesid37351Water treatment technologies to remove contaminants from waste water can be made more efficient by incorporating nanomembranes or catalytic nanoparticles (get more insights into how nanotechnology is applied to water treatment). Compared to conventional treatment techniques, the use of catalysts, especially nanoparticle catalysts, can shorten treatment time, target recalcitrant substances, and selectively transform wastes into valuable products for instance by recovering carbon, nitrogen and phosphorus.   By . Copyright © Nanowerk

An issue with these systems is the expense associated with the initial investment and subsequent replenishment of catalysts. The reason for the high cost of catalytic water treatment is the use of expensive noble metals such as platinum and palladium for catalyzing the degradation of environmental contaminants. In the quest to find equally effective – in some cases even more effective – yet less expensive catalyst alternatives, researchers have developed bimetallic alloys by blending a noble metal nanoparticles with cheaper promoter metals such as copper and nickel. The blending ratio of these metals is an important parameter that controls the reactivity of alloy nanocatalysts. The challenge with this approach is how to find the composition of alloy nanoparticles that show the greatest catalytic reactivity for a contaminant of interest. Doing this requires the synthesis of a series of different nanoparticles which then each needs to be screened for their catalytic activity. Researchers at the University of Notre Dame now have successfully synthesized suspended platinum/nickel nanoalloys using a cycle-controlled microwave-assisted polyol reduction method.

The metal alloy nanoparticles synthesized by this method have a dynamic structure. For example, in the synthesis of platinum (Pt) and nickel (Ni) nanoalloy, a Pt core forms first, which then catalyzes the reduction of Ni2+. Ni then blends with Pt, giving a Pt/Ni alloy shell. After platinum is exhausted, the new shell is completely made of nickel. The team, led by Chongzheng Na, an Assistant Professor in the Department of Civil and Environmental Engineering and Earth Sciences, reported their findings in the August 7, 2014 online edition of Applied Catalysis B: Environmental (“Microwave-assisted optimization of platinum-nickel nanoalloys for catalytic water treatment”).

formation of nanoalloyFormation of the dynamic Pt/Ni nanoalloy under microwave irradiation and the volcano plot of the catalytic rate and surface compositions. (Image: Na group, University of Notre Dame)

“Our one-pot method creates nanoparticles with a range of surface compositions without much change of the particle size,” Hanyu Ma, a Ph.D. student in Na’s group, tells Nanowerk. “The varied surface compositions permit the rapid determination of the optimal Pt/Ni composition to be used as an effective nanoalloy for reducing the model water contaminant p-nitrophenol.” As Na and his team point out, the adoption of this facile synthesis method in catalyst designs may permit the rapid screening of nanoalloys for other water contaminants. Given the compositional dynamics of this technique, a series of nanoalloys with different surface compositions can be quickly synthesized using a single starting solution and the optimal metal ratio experimentally determined to find the best catalytic reactivity for degrading the pollutant. Ma explains that the structure-activity relationship of alloys is often linked to the averaged composition of an entire particle.

“As we have shown in our paper, the average composition could misrepresent the real composition on surface, where reactions occur,” he says. “With active control of the surface composition, we now can ensure that the reactivity is linked to the correct composition of a nanoalloy.” The researchers note that when the precursors of a noble metal and a transition metal react with a mild reactant such as polyol solvents, their difference in redox potential plays an important role, controlling which metal is reduced and which is not. “As far as we know, this has not been discussed explicitly in the past, particularly when microwave irradiation is used,” adds Ma. “At the beginning of the synthesis, the solvent absorbs microwaves and thus is heated to an above-ambient temperature.

At this temperature, polyol can only reduce noble metal cations so noble metal nanoparticles are formed. Once the nanoparticles are formed, they absorbs microwaves themselves – more than the solvent does – giving to a localized elevated temperature and forming nano hot spots around the nanoparticles. At the elevated temperature, transition metal cations can now be reduced so an alloy mixture is deposited on surface.” The surface composition is controlled by the availability of noble and transition metal precursors in solution.

According to the researchers, two factors play critical roles in establishing the compositional dynamics: the difference of redox potentials between noble and transition metals; and the difference of microwave absorptivity between metal nanoparticles and polyol solvent. Whereas in this present paper Na’s team demonstrated the usefulness of microwave-assisted polyol reduction for synthesizing binary nanoalloys with varied surface compositions, they hope to extend its application to the synthesis of ternary, quaternary, and even more sophisticated nanoalloys.