Tag Archives: water-attracting

Better and greener oil recovery

A June 27, 2016 news item on phys.org describes research on achieving better oil recovery,

As oil producers struggle to adapt to lower prices, getting as much oil as possible out of every well has become even more important, despite concerns from nearby residents that some chemicals used to boost production may pollute underground water resources.

Researchers from the University of Houston have reported the discovery of a nanotechnology-based solution that could address both issues – achieving 15 percent tertiary oil recovery at low cost, without the large volume of chemicals used in most commercial fluids.

A June 27, 2016 University of Houston news release (also on EurekAlert) by Jeannie Kever, which originated the news item, provides more detail,

The solution – graphene-based Janus amphiphilic nanosheets – is effective at a concentration of just 0.01 percent, meeting or exceeding the performance of both conventional and other nanotechnology-based fluids, said Zhifeng Ren, MD Anderson Chair professor of physics. Janus nanoparticles have at least two physical properties, allowing different chemical reactions on the same particle.

The low concentration and the high efficiency in boosting tertiary oil recovery make the nanofluid both more environmentally friendly and less expensive than options now on the market, said Ren, who also is a principal investigator at the Texas Center for Superconductivity at UH. He is lead author on a paper describing the work, published June 27 [2016] in the Proceedings of the National Academy of Sciences.

“Our results provide a novel nanofluid flooding method for tertiary oil recovery that is comparable to the sophisticated chemical methods,” they wrote. “We anticipate that this work will bring simple nanofluid flooding at low concentration to the stage of oilfield practice, which could result in oil being recovered in a more environmentally friendly and cost-effective manner.”

In addition to Ren, researchers involved with the project include Ching-Wu “Paul” Chu, chief scientist at the Texas Center for Superconductivity at UH; graduate students Dan Luo and Yuan Liu; researchers Feng Wang and Feng Cao; Richard C. Willson, professor of chemical and biomolecular engineering; and Jingyi Zhu, Xiaogang Li and Zhaozhong Yang, all of Southwest Petroleum University in Chengdu, China.

The U.S. Department of Energy estimates as much as 75 percent of recoverable reserves may be left after producers capture hydrocarbons that naturally rise to the surface or are pumped out mechanically, followed by a secondary recovery process using water or gas injection.

Traditional “tertiary” recovery involves injecting a chemical mix into the well and can recover between 10 percent and 20 percent, according to the authors.

But the large volume of chemicals used in tertiary oil recovery has raised concerns about potential environmental damage.

“Obviously simple nanofluid flooding (containing only nanoparticles) at low concentration (0.01 wt% or less) shows the greatest potential from the environmental and economic perspective,” the researchers wrote.

Previously developed simple nanofluids recover less than 5 percent of the oil when used at a 0.01 percent concentration, they reported. That forces oil producers to choose between a higher nanoparticle concentration – adding to the cost – or mixing with polymers or surfactants.

In contrast, they describe recovering 15.2 percent of the oil using their new and simple nanofluid at that concentration – comparable to chemical methods and about three times more efficient than other nanofluids.

Dan Luo, a UH graduate student and first author on the paper, said when the graphene-based fluid meets with the brine/oil mixture in the reservoir, the nanosheets in the fluid spontaneously go to the interface, reducing interfacial tension and helping the oil flow toward the production well.

Ren said the solution works in a completely new way.

“When it is injected, the solution helps detach the oil from the rock surface,” he said. Under certain hydrodynamic conditions, the graphene-based fluid forms a strong elastic and recoverable film at the oil and water interface, instead of forming an emulsion, he said.

Researchers said the difference is due to the asymmetric property of the 2-dimensional material. Nanoparticles are usually either hydrophobic – water-repelling, like oil – or hydrophilic, water-like, said Feng Wang, a post-doctoral researcher who shared first author-duties with Luo.

“Ours is both,” he said. “Ours is Janus and also strictly amphiphilic.”

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

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration by Dan Luo, Feng Wang, Jingyi Zhu, Feng Cao, Yuan Liu, Xiaogang Li, Richard C. Willson, Zhaozhong Yang, Ching-Wu Chu, and Zhifeng Ren. PNAS 2016 doi: 10.1073/pnas.1608135113 published ahead of print June 27, 2016,

This paper is behind a paywall.

NBD Nano startup company and the Namib desert beetle

In 2001, Andrew Parker and Chris Lawrence published an article in Nature magazine about work which has inspired a US startup company in 2012 to develop a water bottle that fills itself up with water by drawing moisture from the air. Parker’s and Lawrence’s article was titled Water capture by a desert beetle. Here’s the abstract (over 10 years later the article is still behind a paywall),

Some beetles in the Namib Desert collect drinking water from fog-laden wind on their backs1. We show here that these large droplets form by virtue of the insect’s bumpy surface, which consists of alternating hydrophobic, wax-coated and hydrophilic, non-waxy regions. The design of this fog-collecting structure can be reproduced cheaply on a commercial scale and may find application in water-trapping tent and building coverings, for example, or in water condensers and engines.

Some five years later, there was a June 15, 2006 news item on phys.org about the development of a new material based on the Namib desert beetle,

When that fog rolls in, the Namib Desert beetle is ready with a moisture-collection system exquisitely adapted to its desert habitat. Inspired by this dime-sized beetle, MIT [Massachusetts Institute of Technology] researchers have produced a new material that can capture and control tiny amounts of water.

The material combines a superhydrophobic (water-repelling) surface with superhydrophilic (water-attracting) bumps that trap water droplets and control water flow. The work was published in the online version of Nano Letters on Tuesday, May 2 [2006] {behind a paywall}.

Potential applications for the new material include harvesting water, making a lab on a chip (for diagnostics and DNA screening) and creating microfluidic devices and cooling devices, according to lead researchers Robert Cohen, the St. Laurent Professor of Chemical Engineering, and Michael Rubner, the TDK Professor of Polymer Materials Science and Engineering.

The MIT June 14, 2006 news release by Anne Trafton, which originated the news item about the new material, indicates there was some military interest,

The U.S. military has also expressed interest in using the material as a self-decontaminating surface that could channel and collect harmful substances.

The researchers got their inspiration after reading a 2001 article in Nature describing the Namib Desert beetle’s moisture-collection strategy. Scientists had already learned to copy the water-repellent lotus leaf, and the desert beetle shell seemed like another good candidate for “bio-mimicry.”

When fog blows horizontally across the surface of the beetle’s back, tiny water droplets, 15 to 20 microns, or millionths of a meter, in diameter, start to accumulate on top of bumps on its back.

The bumps, which attract water, are surrounded by waxy water-repelling channels. “That allows small amounts of moisture in the air to start to collect on the tops of the hydrophilic bumps, and it grows into bigger and bigger droplets,” Rubner said. “When it gets large, it overcomes the pinning force that holds it and rolls down into the beetle’s mouth for a fresh drink of water.”

To create a material with the same abilities, the researchers manipulated two characteristics — roughness and nanoporosity (spongelike capability on a nanometer, or billionths of a meter, scale).

By repeatedly dipping glass or plastic substrates into solutions of charged polymer chains dissolved in water, the researchers can control the surface texture of the material. Each time the substrate is dipped into solution, another layer of charged polymer coats the surface, adding texture and making the material more porous. Silica nanoparticles are then added to create an even rougher texture that helps trap water droplets.

The material is then coated with a Teflon-like substance, making it superhydrophobic. Once that water-repellent layer is laid down, layers of charged polymers and nanoparticles can be added in certain areas, using a properly formulated water/alcohol solvent mixture, thereby creating a superhydrophilic pattern. The researchers can manipulate the technique to create any kind of pattern they want.

The research is funded by the Defense Advanced Research Projects Agency and the National Science Foundation.

I’m not sure what happened with the military interest or the group working out of MIT in 2006 but on Nov. 23, 2012, BBC News online featured an article about a US startup company, NBD Nano, which aims to bring a self-filling water bottle based on Namib desert beetle to market,

NBD Nano, which consists of four recent university graduates and was formed in May, looked at the Namib Desert beetle that lives in a region that gets about half an inch of rainfall per year.

Using a similar approach, the firm wants to cover the surface of a bottle with hydrophilic (water-attracting) and hydrophobic (water-repellent) materials.

The work is still in its early stages, but it is the latest example of researchers looking at nature to find inspiration for sustainable technology.

“It was important to apply [biomimicry] to our design and we have developed a proof of concept and [are] currently creating our first fully-functional prototype,” Miguel Galvez, a co-founder, told the BBC.

“We think our initial prototype will collect anywhere from half a litre of water to three litres per hour, depending on local environments.”

According to the Nov. 25, 2012 article by Nancy Owano for phys.org, the company is at the prototype stage now,

NBD Nano plans to enter the worldwide marketplace between 2014 and 2015.

You can find out more about NBD Nano here.