Tag Archives: oleophilic

A robot that sucks up oil spills

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I was surprised to find out that between 1989 when the Exxon Valdez oil spill fouled the coastline along Alaska and northern British Columbia and 2010 when the BP (British Petroleum) oil spill fouled the Gulf of Mexico and a number of US states, which border it, and Mexico’s state coastlines, there had been virtually no improvement in the environmental remediation technologies for oil spills (see my June 4, 2010 posting).

This summer we’ve had two major oil spills, one in the Russian Arctic (as noted in my August 14, 2020 posting; scroll down to the subhead ‘As for the Russian Arctic oil spill‘) and in the Indian Ocean near Mauritius and near a coral reef and marine protected areas (see this August 13, 2020 news item on the Canadian Broadcasting Corporation [CBC] news online website).

No word yet on whether or not remediation techniques have improved but this August 6, 2020 article by Adele Peters for Fast Company highlights a new robotic approach to cleaning marine oil spills,

A decade after a BP drilling rig exploded in the Gulf of Mexico, sending an estimated 168 million gallons of oil gushing into the water over the course of months, local wildlife are still struggling to recover. Many of the people who worked to clean up the spill are still experiencing health effects. At the time, the “cleanup” strategy involved setting oil slicks on fire and spraying mass quantities of a chemical meant to disperse it, both of which helped get rid of the oil, but also worsened pollution [emphasis mine].

A new robot designed to clean oil spills, now in development, demonstrates how future spills could be handled differently. The robot navigates autonomously on the ocean surface, running on solar power. When oil sensors on the device detect a spill, it triggers a pump that pushes oil and water inside, where a custom nanomaterial sucks up the oil and releases clean water.

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Kabra [Tejas Sanjay Kabra, a graduate student at North Carolina State University] 3D-printed a small prototype of the robot, which he tested in a lab, a swimming pool, and then the open ocean. (The small version, about two feet across, can collect 20 gallons of oil at a time; the same device can be scaled up to much larger sizes). He now hopes to bring the product to market as quickly as possible, as major oil spills continue to occur—such as the spill in Russia in June that sent more than 20,000 metric tons of diesel into a pristine part of the Arctic.

Peters’s article provides more details and features an embedded video.

Kabra calls his technology, SoilioS (Spilled OIL recovery by Isis & Oleophilic Sponge) and he entered it in the 2020 James Dyson Awards. The undated James Dyson Award news release announcing the 2020 national winners does not include Kabra’s entry. Mind you, over 1700 inventors entered the 2020 competition.

I hope Kabra perseveres as his robot project looks quite interesting for a number of reasons as can be seen in his entry submission (from the James Dyson Award website),

Initially, I started with a literature review on various Nanomaterials made from tree leaves with specific properties of Hydrophobicity and oleophilicity. Then I narrowed down my research on four different types of leaves i.e., Holy basil, betel, subabul, and mango. Nanoparticles from these leaves were made by green synthesis method and SEM, EDX and XRD tests were conducted. From these tests, I found that the efficiency of material made from the subabul tree was max (82.5%). In order to carry out surface cleaning at sea, different robot designs were studied. Initially, the robot was built in a box structure with arms. The arms contained Nano-capillary; however, the prototype was bulky and inefficient. A new model was devised to reduce the weight as well as increase the efficiency of absorbing the oil spill. The new robot was designed to be in a meta-stable state. The curves of the robot are designed in such a way that it gives stability as well as hold all the components. The top part of the robot is a hollow dome to improve the stability in water. The robot is 3D printed to reduce weight. The 3D printed robot was tested in a pool. Further, work is going on to build a 222 feet robot to test with hardware suitable for sea.

Here’s what SoilioS looks like,

[downloaded from https://www.jamesdysonaward.org/en-US/2020/project/soilios/]

Kabra described what makes his technology from what is currently the state-of-the-art and his future plans (from the James Dyson Award website),

The current technology uses carbon Nano-particle, and some other uses plastic PVC with a chemical adhesive, which is harmful to the environment. On the other hand, SoilioS uses Nano-material made from tree leaves. The invented technology absorbs the oil and stores inside the container with a recovery rate of 80%. The recovered oil can be used for further application; however, on the other hand, the current products burn the oil [emphasis mine] at the cleaning site itself without any recovery rate, thereby increasing pollution. The durability of the invented technology is 8-10 years, and the Nanomaterial used for cleaning the oil spill is reusable for 180 cycles. On the other hand, the durability of the current technology is up to 3-5 years, and the material used is non-reusable. The cost of the invented product is only $5 and on the other hand, the existing technology costs up to $750.

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I aim to develop, manufacture, and practically test the robot prototype in the sea so that it can be used to solve oil spill issues and can save billions of dollars. I hope this device will help the environment in a lot of ways and eventually decrease the side effects caused due to oil spills such as leukemia and dying marine life. Currently, I am testing the product on different grades of oil to improve its efficiency further and improving its scope of the application so that it can also be used in industries and household purposes.

I wish Kabra good luck as he works to bring his technology to market.

Netting oil spills the nano way

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Given current local events (April 8, 2015 oil spill in English Bay of 2700 litres (or more) of fuel in Vancouver, Canada), this news item about a mesh useful for oil cleanups seems quite timely. From an April 15, 2015 news item on ScienceDaily,

The unassuming piece of stainless steel mesh in a lab at The Ohio State University doesn’t look like a very big deal, but it could make a big difference for future environmental cleanups.

Water passes through the mesh but oil doesn’t, thanks to a nearly invisible oil-repelling coating on its surface.

In tests, researchers mixed water with oil and poured the mixture onto the mesh. The water filtered through the mesh to land in a beaker below. The oil collected on top of the mesh, and rolled off easily into a separate beaker when the mesh was tilted.

The mesh coating is among a suite of nature-inspired nanotechnologies under development at Ohio State and described in two papers in the journal Nature Scientific Reports. Potential applications range from cleaning oil spills to tracking oil deposits underground.

An April 15, 2015 Ohio State University news release (also on EurekAlert*) by Pam Frost Gorder, which originated the news item, expands on the theme (unusually I’ve left the links undisturbed),

“If you scale this up, you could potentially catch an oil spill with a net,” said Bharat Bhushan, Ohio Eminent Scholar and Howard D. Winbigler Professor of mechanical engineering at Ohio State.

The work was partly inspired by lotus leaves, whose bumpy surfaces naturally repel water but not oil. To create a coating that did the opposite, Bhushan and postdoctoral researcher Philip Brown chose to cover a bumpy surface with a polymer embedded with molecules of surfactant—the stuff that gives cleaning power to soap and detergent.

They sprayed a fine dusting of silica nanoparticles onto the stainless steel mesh to create a randomly bumpy surface and layered the polymer and surfactant on top.

The silica, surfactant, polymer, and stainless steel are all non-toxic and relatively inexpensive, said Brown. He estimated that a larger mesh net could be created for less than a dollar per square foot.

Because the coating is only a few hundred nanometers (billionths of a meter) thick, it is mostly undetectable. To the touch, the coated mesh doesn’t feel any bumpier than uncoated mesh. The coated mesh is a little less shiny, though, because the coating is only 70 percent transparent.

The researchers chose silica in part because it is an ingredient in glass, and they wanted to explore this technology’s potential for creating smudge-free glass coatings. At 70 percent transparency, the coating could work for certain automotive glass applications, such as mirrors, but not most windows or smartphone surfaces.

“Our goal is to reach a transparency in the 90-percent range,” Bhushan said. “In all our coatings, different combinations of ingredients in the layers yield different properties. The trick is to select the right layers.”

He explains that combinations of layers yield nanoparticles that bind to oil instead of repelling it. Such particles could be used to detect oil underground or aid removal in the case of oil spills.

The shape of the nanostructures plays a role, as well. In another project, research assistant Dave Maharaj is investigating what happens when a surface is made of nanotubes. Rather than silica, he experiments with molybdenum disulfide nanotubes, which mix well with oil. The nanotubes are approximately a thousand times smaller than a human hair.

Maharaj measured the friction on the surface of the nanotubes, and compressed them to test how they would hold up under pressure.

“There are natural defects in the structure of the nanotubes,” he said. “And under high loads, the defects cause the layers of the tubes to peel apart and create a slippery surface, which greatly reduces friction.”

Bhushan envisions that the molybdenum compound’s compatibility with oil, coupled with its ability to reduce friction, would make it a good additive for liquid lubricants. In addition, for micro- and nanoscale devices, commercial oils may be too sticky to allow for their efficient operation. Here, he suspects that the molybdenum nanotubes alone could be used to reduce friction.

This work began more than 10 years ago, when Bhushan began building and patenting nano-structured coatings that mimic the texture of the lotus leaf. From there, he and his team have worked to amplify the effect and tailor it for different situations.

“We’ve studied so many natural surfaces, from leaves to butterfly wings and shark skin, to understand how nature solves certain problems,” Bhushan said. “Now we want to go beyond what nature does, in order to solve new problems.”

“Nature reaches a limit of what it can do,” agreed Brown. “To repel synthetic materials like oils, we need to bring in another level of chemistry that nature doesn’t have access to.”

This work was partly funded by the American Chemical Society Petroleum Research Fund, the National Science Foundation, and Dexerials Corporation (formerly a chemical division of Sony Corp.) in Japan.

Here are links to and citations for the papers,

Mechanically durable, superoleophobic coatings prepared by layer-by-layer technique for anti-smudge and oil-water separation by Philip S. Brow & Bharat Bhushan. Scientific Reports 5, Article number: 8701 doi:10.1038/srep08701 Published 03 March 2015

Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and Carbon nanohorns by Dave Maharaj, & Bharat Bhushan. Scientific Reports 5, Article number: 8539 doi:10.1038/srep08539 Published 23 February 2015

Both papers are open access.

* EurekAlert link added Apr.16, 2015 at 1300 PST.

Nanosponges clean up spilled oil and release the oil for future use

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The nanosponges that have been developed by a joint team of Rice University and Penn State University researchers look pretty exciting (wish I could write a better headline about them). Here’s the researcher describing them,

I find the idea that the sponges can be reused and the oil still put to use quite compelling. From the April 16, 2012 news item on Nanowerk,

… Daniel Hashim, a graduate student in the Rice lab of materials scientist Pulickel Ajayan, said the blocks are both superhydrophobic (they hate water, so they float really well) and oleophilic (they love oil). The nanosponges, which are more than 99 percent air, also conduct electricity and can easily be manipulated with magnets.

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To demonstrate, Hashim dropped the sponge into a dish of water with used motor oil floating on top. The sponge soaked it up. He then put a match to the material, burned off the oil and returned the sponge to the water to absorb more. The robust sponge can be used repeatedly and stands up to abuse; he said a sample remained elastic after about 10,000 compressions in the lab. The sponge can also store the oil for later retrieval, he said.

“These samples can be made pretty large and can be easily scaled up,” said Hashim, holding a half-inch square block of billions of nanotubes. “They’re super-low density, so the available volume is large. That’s why the uptake of oil can be so high.” He said the sponges described in the paper can absorb more than a hundred times their weight in oil.

Nanosponges have been made from carbon nan0tubes before now (from the Feb. 8, 2010 article by Michael Berger on Nanowerk),

Carbon nanotubes (CNTs) are ‘strange’ nanostructures in a sense that they have both high mechanical strength and extreme flexibility. Deforming a carbon nanotube into any shape would not easily break the structure, and it recovers to original morphology in perfect manner. Researchers in China are exploiting this phenomenon by making CNT sponges consisting of a large amount of interconnected nanotubes, thus showing a combination of useful properties such as high porosity, super elasticity, robustness, and little weight (1% of water density).

The nanotube sponges not only show exciting properties as a porous material but they also are very promising to be used practically in a short time. The production method is simple and scalable, the cost is low, and the sponges can find immediate use in many fields related to water purification.

“We hope to give an example to industry that this sponge is a real thing they can prepare at low cost, make versatile products with high performance, and solve environmental problems utilizing nanotechnology,” [says] Anyuan Cao, a professor in the Department of Advanced Materials and Nanotechnology at Peking University …

The difference between the nanosponges made in 2010 and the ones made in 2012 is the fabrication process. From the April 16, 2012 news item on Nanowerk,

Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry, said multiwalled carbon nanotubes grown on a substrate via chemical vapor deposition usually stand up straight without any real connections to their neighbors. But the boron-introduced defects induced the nanotubes to bond at the atomic level, which tangled them into a complex network. Nanotube sponges with oil-absorbing potential have been made before (see paper in Advanced Materials: “Carbon Nanotube Sponges”), but this is the first time the covalent junctions between nanotubes in such solids have been convincingly demonstrated, he said.

“The interactions happen as they grow, and the material comes out of the furnace as a solid,” Ajayan said. [emphasis mine] “People have made nanotube solids via post-growth processing but without proper covalent connections. The advantage here is that the material is directly created during growth and comes out as a cross-linked porous network.

By comparison, the team in China used this process (from the Feb. 8, 2012 article),

The scientists synthesized the sponges by a chemical vapor deposition (CVD) process during which the CNTs (multi-walled nanotubes with diameters in the range of 30 to 50nm and lengths of tens to hundreds of micrometers,) self-assembled into a porous, interconnected, three-dimensional framework.

The research team had collaborators from the US, Mexico, Japan, Spain, and Belgium. From the April 16, 2012 news release on EurekAlert,

When he was an undergraduate student of Ajayan’s at Rensselaer Polytechnic Institute, Hashim and his classmates discovered hints of a topological solution to the problem while participating in a National Science Foundation exchange program at the Institute of Scientific Research and Technology (IPICYT) in San Luis Potosí, Mexico. The paper’s co-author, Mauricio Terrones, a professor of physics, materials science and engineering at Penn State University with an appointment at Shinshu University, Japan, led a nanotechnology lab there.

“Our goal was to find a way to make three-dimensional networks of these carbon nanotubes that would form a macroscale fabric — a spongy block of nanotubes that would be big and thick enough to be used to clean up oil spills and to perform other tasks,” Terrones said. “We realized that the trick was adding boron — a chemical element next to carbon on the periodic table — because boron helps to trigger the interconnections of the material. To add the boron, we used very high temperatures and we then ‘knitted’ the substance into the nanotube fabric.”

For anyone who would like to read further about this work (from the April 16, 2012 news release on EurekAlert),

The paper’s co-authors are Narayanan Narayanan, Myung Gwan Hahm, Joseph Suttle and Robert Vajtai, all of Rice; Jose Romo-Herrera of the University of Vigo, Spain; David Cullen and Bobby Sumpter of Oak Ridge National Laboratory, Oak Ridge, Tenn.; Peter Lezzi and Vincent Meunier of Rensselaer Polytechnic Institute; Doug Kelkhoff of the University of Illinois at Urbana-Champaign; E. Muñoz-Sandoval of the Instituto de Microelectrónica de Madrid; Sabyasachi Ganguli and Ajit Roy of the Air Force Research Laboratory, Dayton, Ohio (on loan from IPICYT); David Smith of Arizona State University; and Humberto Terrones of Oak Ridge National Lab and the Université Catholique de Louvain, Belgium.

The article is titled, Covalently bonded three-dimensional carbon nanotube solids via boron induced nanojunctions, and has been published as an open access article in Nature’s Scientific Reports.

I did mention the nanosponges developed in China in my Feb. 9, 2010 posting.