Tag Archives: Vinayak Dravid

Sponge coated with nanoparticles removes lead from water

It doesn’t look like much but who cares when it does the job and is being made available commercially,

Caption: Commercially available cellulose sponge coated in manganese-doped goethite nanoparticles. Credit: Caroline Harms/Northwestern University

A May 11, 2023 news item on Nanowerk announces the research,

Northwestern University engineers have developed a new sponge that can remove metals — including toxic heavy metals like lead and critical metals like cobalt — from contaminated water, leaving safe, drinkable water behind.

In proof-of-concept experiments, the researchers tested their new sponge on a highly contaminated sample of tap water, containing more than 1 part per million of lead. With one use, the sponge filtered lead to below detectable levels.

After using the sponge, researchers also were able to successfully recover metals and reuse the sponge for multiple cycles. The new sponge shows promise for future use as an inexpensive, easy-to-use tool in home water filters or large-scale environmental remediation efforts.

A May 10, 2023 Northwestern University news release on EurekAlert (also received via email) provides more detail, Note: Links have been removed,

The study was published late yesterday (May 10 [2023]) in the journal ACS ES&T Water. The paper outlines the new research and sets design rules for optimizing similar platforms for removing — and recovering — other heavy-metal toxins, including cadmium, arsenic, cobalt and chromium.

“The presence of heavy metals in the water supply is an enormous public health challenge for the entire globe,” said Northwestern’s Vinayak Dravid, senior author of the study. “It is a gigaton problem that requires solutions that can be deployed easily, effectively and inexpensively. That’s where our sponge comes in. It can remove the pollution and then be used again and again.”

Dravid is the Abraham Harris Professor of Materials Science and Engineering at Northwestern’s McCormick School of Engineering and director of global initiatives at the International Institute for Nanotechnology.

Sopping up spills

The project builds on Dravid’s previous work to develop highly porous sponges for various aspects of environmental remediation. In May 2020, his team unveiled a new sponge designed to clean up oil spills. [Note: My June 25, 2020 posting highlights the work and includes an embedded video demonstration of the technology.] The nanoparticle-coated sponge, which is now being commercialized by Northwestern spinoff MFNS Tech, offers a more efficient, economic, ecofriendly and reusable alternative to current approaches to oil spills.

But Dravid knew it wasn’t enough.

“When there is an oil spill, you can remove the oil,” he said. “But there also are toxic heavy metals — like mercury, cadmium, sulfur and lead — in those spills. So, even when you remove the oil, some of the other toxins might remain.

Rinse and repeat

To tackle this aspect of the issue, Dravid’s team, again, turned to sponges coated with an ultrathin layer of nanoparticles. After testing many different types of nanoparticles, the team found that a manganese-doped goethite coating worked best. Not only are manganese-doped goethite nanoparticles inexpensive to make, easily available and nontoxic to human, they also have the properties necessary to selectively remediate heavy metals.

“You want a material with a high surface area, so there’s more room for the lead ions to stick to it,” said Benjamin Shindel, a Ph.D. student in Dravid’s lab and the paper’s first author. “These nanoparticles have high-surface areas and abundant reactive surface sites for adsorption and are stable, so they can be reused many times.”

The team synthesized slurries of manganese-doped goethite nanoparticles, as well as several other compositions of nanoparticles, and coated commercially available cellulose sponges with these slurries. Then, they rinsed the coated sponges with water in order to wash away any loose particles. The final coatings measured just tens of nanometers in thickness.

When submerged into contaminated water, the nanoparticle-coated sponge effectively sequested lead ions. The U.S. Food and Drug Administration requires that bottled drinking water is below 5 parts per billion of lead. In filtration trials, the sponge lowered the amount of lead to approximately 2 parts per billion, making it safe to drink.

“We’re really happy with that,” Shindel said. “Of course, this performance can vary based on several factors. For instance, if you have a large sponge in a tiny volume of water, it will perform better than a tiny sponge in a huge lake.”

Recovery bypasses mining

From there, the team rinsed the sponge with mildly acidified water, which Shindel likened to “having the same acidity of lemonade.” The acidic solution caused the sponge to release the lead ions and be ready for another use. Although the sponge’s performance declined after the first use, it still recovered more than 90% of the ions during subsequent use cycles.

This ability to gather and then recover heavy metals is particularly valuable for removing rare, critical metals, such as cobalt, from water sources. A common ingredient in lithium-ion batteries, cobalt is energetically expensive to mine and accompanied by a laundry list of environmental and human costs.

If researchers could develop a sponge that selectively removes rare metals, including cobalt, from water, then those metals could be recycled into products like batteries.

“For renewable energy technologies, like batteries and fuel cells, there is a need for metal recovery,” Dravid said. “Otherwise, there is not enough cobalt in the world for the growing number of batteries. We must find ways to recover metals from very dilute solutions. Otherwise, it becomes poisonous and toxic, just sitting there in the water. We might as well make something valuable with it.”

Standardized scale

As a part of the study, Dravid and his team set new design rules to help others develop tools to target particular metals, including cobalt. Specifically, they pinpointed which low-cost and nontoxic nanoparticles also have high-surface areas and affinities for sticking to metal ions. They studied the performance of coatings of manganese, iron, aluminum and zinc oxides on lead adsorption. Then, they established relationships between the structures of these nanoparticles and their adsorptive properties.

Called Nanomaterial Sponge Coatings for Heavy Metals (or “Nano-SCHeMe”), the environmental remediation platform can help other researchers differentiate which nanomaterials are best suited for particular applications.

“I’ve read a lot of literature that compares different coatings and adsorbents,” said Caroline Harms, an undergraduate student in Dravid’s lab and paper co-author. “There really is a lack of standardization in the field. By analyzing different types of nanoparticles, we developed a comparative scale that actually works for all of them. It could have a lot of implications in moving the field forward.”

Dravid and his team imagine that their sponge could be used in commercial water filters, for environmental clean-up or as an added step in water reclamation and treatment facilities.

“This work may be pertinent to water quality issues both locally and globally,” Shindel said. “We want to see this out in the world, where it can make a real impact.”

The study, “Nano-SCHeME: Nanomaterial Sponge Coatings for Heavy Metals, an environmental remediation platform,” was supported by the National Science Foundation and U.S. Department of Energy.

Editor’s note: Dravid and Northwestern have financial interests (equities, royalties) in MFNS Tech.

Here’s a link to and a citation for the paper,

Nano-SCHeme: Nanomaterial Sponge Coatings for Heavy Metals, an Environmental Remediation Platform by Benjamin Shindel, Stephanie M. Ribet, Caroline Harms, Vikas Nandwana, and Vinayak P. Dravid. ACS EST Water 2023, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acsestwater.2c00646 Publication Date:May 10, 2023 © 2023 American Chemical Society

This paper is behind a paywall.

You can find the MFNS Tech website here.

Clean up oil spills with a smart sponge?

I love the part with the magnet,

All of the main points are made in the video but for those who like text, there’s a May 28, 2020 news item on phys.org describing this new smart sponge for cleaning up oil spills (Note: Links have been removed),

A Northwestern University-led [Chicago, Illinois, US] team has developed a highly porous smart sponge that selectively soaks up oil in water.

With an ability to absorb more than 30 times its weight in oil, the sponge could be used to inexpensively and efficiently clean up oil spills without harming marine life. After squeezing the oil out of the sponge, it can be reused many dozens of times without losing its effectiveness.

“Oil spills have devastating and immediate effects on the environment, human health and economy,” said Northwestern’s Vinayak Dravid, who led the research. “Although many spills are small and may not make the evening news, they are still profoundly invasive to the ecosystem and surrounding community. Our sponge can remediate these spills in a more economic, efficient and eco-friendly manner than any of the current state-of-the-art solutions.”

A May 28, 2020 Northwestern University news release (also on EurekAlert), which originated the news item, reveals (as did the video) the characteristics that make this smart sponge particularly interesting,

Oil spill clean-up is an expensive and complicated process that often harms marine life and further damages the environment. Currently used solutions include burning the oil, using chemical dispersants to breakdown oil into very small droplets, skimming oil floating on top of water and/or absorbing it with expensive, unrecyclable sorbents.

“Each approach has its own drawbacks and none are sustainable solutions,” Nandwana [Vikas Nandwana, a senior research associate in Dravid’s laboratory] said. “Burning increases carbon emissions and dispersants are terribly harmful for marine wildlife. Skimmers don’t work in rough waters or with thin layers of oil. And sorbents are not only expensive, but they generate a huge amount of physical waste — similar to the diaper landfill issue.”

The Northwestern solution bypasses these challenges by selectively absorbing oil and leaving clean water and unaffected marine life behind. The secret lies in a nanocomposite coating of magnetic nanostructures and a carbon-based substrate that is oleophilic (attracts oil), hydrophobic (resists water) and magnetic. The nanocomposite’s nanoporous 3D structure selectively interacts with and binds to the oil molecules, capturing and storing the oil until it is squeezed out. The magnetic nanostructures give the smart sponge two additional functionalities: controlled movement in the presence of an external magnetic field and desorption of adsorbed components, such as oil, in a simulated and remote manner.

The OHM (oleophilic hydrophobic magnetic) nanocomposite slurry can be used to coat any cheap, commercially available sponge. The researchers applied a thin coating of the slurry to the sponge, squeezed out the excess and let it dry. The sponge is quickly and easily converted into a smart sponge (or “OHM sponge”) with a selective affinity for oil.

Vinayak and his team tested the OHM sponge with many different types of crude oils of varying density and viscosity. The OHM sponge consistently absorbed up to 30 times its weight in oil, leaving the water behind. To mimic natural waves, researchers put the OHM sponge on a shaker submerged in water. Even after vigorous shaking, the sponge release less than 1% of its absorbed oil back into the water.

“Our sponge works effectively in diverse and extreme aquatic conditions that have different pH and salinity levels,” Dravid said. “We believe we can address a giga-ton problem with a nanoscale solution.”

“We are excited to introduce such smart sponges as an environmental remediation platform for selectively removing and recovering pollutants present in water, soil and air, such as excess nutrients, heavy metal contaminants, VOC/toxins and others,” Nandwana said. “The nanostructure coating can be tailored to selectively adsorb (and later desorb) these pollutants.”

The team also is working on another grade of OHM sponge that can selectively absorb (and later recover) excess dissolved nutrients, such as phosphates, from fertilizer runoff and agricultural pollution. Stephanie Ribet, a Ph.D. candidate in Dravid’s lab and paper coauthor is pursuing this topic. The team plans to develop and commercialize OHM technology for environmental clean-up.

Bravo to professor Vinayak Dravid and his team. I’m sure I’m not alone in wishing you and your team the best of luck as you continue to develop this remediation technology.

Here’s a link to and a citation for the paper,

OHM Sponge: A Versatile, Efficient, and Ecofriendly Environmental Remediation Platform by Vikas Nandwana, Stephanie M. Ribet, Roberto D. Reis, Yuyao Kuang, Yash More, and Vinayak P. Dravid. Ind. Eng. Chem. Res. 2020, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acs.iecr.0c01493 Publication Date:May 12, 2020 Copyright © 2020 American Chemical Society

This paper is behind a paywall.

Vote for favourite EnvisioNano image ’til June 17, 2016

A June 6, 2016 news item on Nanowerk announces the latest and last voting round of the semifinal judging for the 2016 EnvisioNano contest,

Members of the public are invited to vote for the best images in this round of the National Nanotechnology Initiative (NNI) EnvisioNano contest.

Now in its third round, this contest has drawn submissions from students at top labs and schools across the United States.

This round includes images such as this one (from the 3rd voting round of the EnvisioNano page),

Iron Honeycomb: Hexagonal close-packed assembly of iron oxide nanoparticles Credits: Vikas Nandwana Advisor: Vinayak Dravid Department of Materials Science and Engineering Northwestern University

Iron Honeycomb: Hexagonal close-packed assembly of iron oxide nanoparticles Credits: Vikas Nandwana Advisor: Vinayak Dravid Department of Materials Science and Engineering Northwestern University

Nandwana also provides this description of his image,

Description: The particles shown here are made of iron oxide, or rust – just like on a car. But these nanoparticles are tiny, 100,000 times thinner than a sheet of paper. At such a small size, they demonstrate some unique properties that can be used to detect and treat diseases like cancer by just applying external magnetic field without any side effects. Due to the same size and shape, the magnetic nanoparticles self-assemble (or come together) into a closely-packed honeycomb pattern.  Iron oxide nanoparticles like these are already used to help people suffering from iron deficiency (anemia). Researchers study how these magnetic nanoparticles interact with each other and tissues in the body, which can open new avenues for nontoxic, targeted tests and treatments for cancer, Alzheimer’s and cardiovascular disease.
Laboratory website: http://vpd.ms.northwestern.edu/
Technique: Transmission Electron Microscopy
Funding Source: NTU-NU Institute for NanoMedicine located at the International Institute for Nanotechnology, Northwestern University, USA and the Nanyang Technological University, Singapore.

A June 6, 2016 US National Nanotechnology Initiative news release, which originated the news item, gives more details,

In the first two rounds of the EnvisioNano contest, student images racked up over 41,000 online views and both previous winning images were featured on the back cover of the NNI Supplement to the President’s 2017 Budget! We encourage everyone to cast votes for their favorite images. All students have provided a description of their photos and research, allowing the viewer to envision where the research is headed and to learn how seeing at the nanoscale is important to reaching that vision. So, as you view the pictures, take a moment to learn about the research and how nanotechnology may improve your life.

Voting starts Monday, June 6th, and is open until June 17th [2016].
View the images and cast your vote at: www.nano.gov/EnvisioNanoVoting.

Once this voting round is completed, judges from the NNI will select the final winning image.

There are a few more details about the contest on this Envisio Nano page. It may be of interest to note that voting ends at 12 pm (noon) on June 17, 2016.

2015 winners were featured (as mentioned earlier) on the cover of the 2017 NNI budget supplement. I wrote about the supplement and embedded images of the cover in my April 4, 2016 posting.

$81M for US National Nanotechnology Coordinated Infrastructure (NNCI)

Academics, small business, and industry researchers are the big winners in a US National Science Foundation bonanza according to a Sept. 16, 2015 news item on Nanowerk,

To advance research in nanoscale science, engineering and technology, the National Science Foundation (NSF) will provide a total of $81 million over five years to support 16 sites and a coordinating office as part of a new National Nanotechnology Coordinated Infrastructure (NNCI).

The NNCI sites will provide researchers from academia, government, and companies large and small with access to university user facilities with leading-edge fabrication and characterization tools, instrumentation, and expertise within all disciplines of nanoscale science, engineering and technology.

A Sept. 16, 2015 NSF news release provides a brief history of US nanotechnology infrastructures and describes this latest effort in slightly more detail (Note: Links have been removed),

The NNCI framework builds on the National Nanotechnology Infrastructure Network (NNIN), which enabled major discoveries, innovations, and contributions to education and commerce for more than 10 years.

“NSF’s long-standing investments in nanotechnology infrastructure have helped the research community to make great progress by making research facilities available,” said Pramod Khargonekar, assistant director for engineering. “NNCI will serve as a nationwide backbone for nanoscale research, which will lead to continuing innovations and economic and societal benefits.”

The awards are up to five years and range from $500,000 to $1.6 million each per year. Nine of the sites have at least one regional partner institution. These 16 sites are located in 15 states and involve 27 universities across the nation.

Through a fiscal year 2016 competition, one of the newly awarded sites will be chosen to coordinate the facilities. This coordinating office will enhance the sites’ impact as a national nanotechnology infrastructure and establish a web portal to link the individual facilities’ websites to provide a unified entry point to the user community of overall capabilities, tools and instrumentation. The office will also help to coordinate and disseminate best practices for national-level education and outreach programs across sites.

New NNCI awards:

Mid-Atlantic Nanotechnology Hub for Research, Education and Innovation, University of Pennsylvania with partner Community College of Philadelphia, principal investigator (PI): Mark Allen
Texas Nanofabrication Facility, University of Texas at Austin, PI: Sanjay Banerjee

Northwest Nanotechnology Infrastructure, University of Washington with partner Oregon State University, PI: Karl Bohringer

Southeastern Nanotechnology Infrastructure Corridor, Georgia Institute of Technology with partners North Carolina A&T State University and University of North Carolina-Greensboro, PI: Oliver Brand

Midwest Nano Infrastructure Corridor, University of  Minnesota Twin Cities with partner North Dakota State University, PI: Stephen Campbell

Montana Nanotechnology Facility, Montana State University with partner Carlton College, PI: David Dickensheets
Soft and Hybrid Nanotechnology Experimental Resource,

Northwestern University with partner University of Chicago, PI: Vinayak Dravid

The Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure, Virginia Polytechnic Institute and State University, PI: Michael Hochella

North Carolina Research Triangle Nanotechnology Network, North Carolina State University with partners Duke University and University of North Carolina-Chapel Hill, PI: Jacob Jones

San Diego Nanotechnology Infrastructure, University of California, San Diego, PI: Yu-Hwa Lo

Stanford Site, Stanford University, PI: Kathryn Moler

Cornell Nanoscale Science and Technology Facility, Cornell University, PI: Daniel Ralph

Nebraska Nanoscale Facility, University of Nebraska-Lincoln, PI: David Sellmyer

Nanotechnology Collaborative Infrastructure Southwest, Arizona State University with partners Maricopa County Community College District and Science Foundation Arizona, PI: Trevor Thornton

The Kentucky Multi-scale Manufacturing and Nano Integration Node, University of Louisville with partner University of Kentucky, PI: Kevin Walsh

The Center for Nanoscale Systems at Harvard University, Harvard University, PI: Robert Westervelt

The universities are trumpeting this latest nanotechnology funding,

NSF-funded network set to help businesses, educators pursue nanotechnology innovation (North Carolina State University, Duke University, and University of North Carolina at Chapel Hill)

Nanotech expertise earns Virginia Tech a spot in National Science Foundation network

ASU [Arizona State University] chosen to lead national nanotechnology site

UChicago, Northwestern awarded $5 million nanotechnology infrastructure grant

That is a lot of excitement.