Francesco Stellacci, MIT, and Nature Nanotechnology
A nanowire membrane that sops up oil while repelling water could be used for cleaning up oil spills.
A thin membranes made from a web of nanowires might become a promising tool for cleaning up oil spills and removing toxic contaminants from groundwater. When dipped into a mixture of water and oil, the 50-micrometer-thick membrane absorbs the oil, swelling to 20 times its weight.
Typically, oil spills are cleaned up using the same basic technology used 20 years ago. This includes using absorbent materials to sop up traces of oil. Natural sorbents such as hay and cellulose can soak up between 3 and 15 times their weight in oil, while synthetic polymer-based sorbents can absorb up to 70 times their weight. But these materials tend to absorb water as well.
The new membrane absorbs oil and solvents and is superhydrophobic, which means it strongly repels water. "If you were to put it in water for a month and take it out it would still be dry," says Francesco Stellacci, the MIT Materials science and engineering professor who led the work, published online in Nature Nanotechnology. Stellaci says the material should not be too expensive to make in large quantities and can be easily reused many times, although the researchers haven't measured how many times yet.
Michael Rubner, an MIT materials science and engineering professor who was not involved in the project, says that the membrane's reusability is its most distinctive feature. Other hydrophobic structures have typically been made from organic materials. The inorganic nanowires can handle temperatures up to 600 degrees Celsius, where organic materials would degrade. "If the membrane becomes foul with oil or you have to remove the oil, ... [you] can basically cook it and clean it up and, in principle, use it over and over again," Rubner says.
The membrane is a mat of potassium manganese oxide nanowires, each about 20 nanometers wide. Stellacci and his colleagues assemble the mats using a method similar to one used to produce paper: they make a suspension of nanowires and dry it on a substrate. They have made membranes that are 27 centimeters on each side, but Stellacci says they could be made in larger mats.
Two important characteristics give the membrane its exceptional oil-absorbing and water-repelling properties. First, the nanowire mesh has tiny pores--10-nanometers wide on averagecapable of wicking water and other liquids up into the membrane. To keep water away, researchers coat the membrane with water-repelling silicone. The result: water rolls off the surface of the membrane while oil travels quickly up the pores. Stellacci and his colleagues tested the membrane with mixtures of different organic solvents and oils, including motor oil, gasoline and toluene.
Safety upgrades are critical but could mean higher prices for oil and gas.
But BP's "top kill" method to stanch the spill could also break it wide open.
The disaster exposes overreliance on blowout preventers that has been long disparaged by insiders.
Is bioremediation not a workable solution?
It might seem off-topic as the approach is different, however I believe that since the overall problem that we are trying to solve is the same, wanted to add my 2 cents. I wanted to bring out the benefits of bioremediation process.
Regarding bioremediation, when implemented right, can cleanup oil spills effectively and in our experience at Sarva Bio Remed, with confidence. I can say that in the last 8 years our company has been involved in cleaning up some heavily contaminated sites with TPH ranging from 700,000 ppm to 70,000 ppm to less than 200 ppm within 3 - 4 weeks for soil and spills on water usually took similar time. I tend to agree with Doug Helton in the article that oil spill cleanup become messy using sorbent pad based approaches and also adds to the cost of cleanup, more so in the US where USCG estimates the costs of cleanup to be about $500 USD per gallon of oil spilled. In our experience the reason we have achieved the success is the near zero maintenance and also the consistency of the success of our approach. The solution we offer is cost-effective to about $10 per gallon of oil spilled. Since our products are commercially available, my post could be considered shameless commerce. OTOH, if the reporter had done some additional research, we would have come up in a simple google search and then I would not have to make this post(;-)). My post is also presented in this forum as self-interest as the total dollars allocated in solving the existing oil due to past spills and to address future(however much we would like to wish otherwise) is limited therefore competing technologies need to sort out the best approach as it is the tax dollars that somehow get diverted into oil spill cleanup as many polluters somehow were able to limit their liability for any oil spill. As a recent example, the COSCO Busan spill cost the polluter about 50M USD for 50,000 gallons of oil spill: about $1000 per gallon of spilled oil. We have been trying to work with environment agencies to help outline the benefits of a working bioremediation solution (such as ours) of course its a slow process and the baggage bioremediation carries is quite significant to overcome. Thanks for the post, this keeps the problem alive and hope someone is willing to solve the problem soon and put some weight behind a working solution. I am sure a lot of the information is common knowledge and I was using the numbers to present the viability of a solution and the target end-points for a successful approach. If the reporter of this article needs to contact me, please feel free to email me.
Thanks,
Dinkar
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
This document is part of the “How-To Guide for Most Common Measurements” centralized resource portal. This tutorial provides a detailed guide for measurement and device considerations to take temperature measurements using thermocouples. Get an introduction to thermocouples, which are inexpensive sensing devices widely used with PC-based data acquisition systems. Also review some specific thermocouple examples and learn how thermocouples work and ways to integrate them into a data acquisition measurement system.
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flared0ne
395 Comments
Some interesting opportunities this opens up...
Imagine a relatively narrow (12 inches, say) "ribbon" of this material, in something approximating a continuous loop, going "out" or "down" to a spill, a seep, a source of hydrocarbons that wants to be transported/cleaned-up/captured. After spending some minimal amount of time "in contact with" the target hydrocarbons, it spools on "back" or "up" to a stratified cracking sleeve that sequences up in temperature as the "ribbon" travels through, gasifying various compounds off of the "sponge".
Given varying required "dwell-times" at various temperatures, a constantly moving "belt" might warrant folding to stay within some thermal ranges long enough.
Possibly more efficient than a "closed loop" approximation might be a pair of "feed" and "uptake" spools, where you plan to "cook off" and recover the scavenged material after you acquire some cost-effective number of takeup spools that justify heating up the recovery oven.
Might be feasible to improve productivity of some slow-producing oil strata, depending on sufficient contact area "down-hole"...
And if the solvent selectivity can be engineered via pore-size manipulation, for example (similar to zeolite-catalyst engineering, I imagine), a whole new range of catalytic options should become feasible.
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flared0ne
395 Comments
Re: Some interesting opportunities this opens up...
I don't recall hearing any description of the thermal conductivity of this type of material... Something to look up.
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Brian H
60 Comments
Re: Some interesting opportunities this opens up...
Very smart! I wonder if tubes of the material might be used for purification; suck up contaminated water at one end, pump purified out the other. External systems like you describe might contact the pipes and draw off accumulated oil as fast as it built up in the pipe walls.
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