Nav: Home

Oil-catching sponge could soak up residue from offshore drilling

December 16, 2019

Drilling and fracking for oil under the seabed produces 100 billion barrels of oil-contaminated wastewater every year by releasing tiny oil droplets into surrounding water.

Most efforts to remove oil from water focus on removing large oil slicks from industrial spills but these aren't suitable for removing tiny droplets. Instead, scientists are looking for new ways to clean the water.

Now, researchers at the University of Toronto (U of T) and Imperial College London have developed a sponge that removes over 90 per cent of oil microdroplets from wastewater within ten minutes.

After capturing oil from wastewater, the sponge can be treated with a solvent, which releases the oil from the sponge. The oil can then be recycled; the sponge, ready to be used again.

The sponge improves upon a previous concept: lead author Dr Pavani Cherukupally, now of Imperial's Department of Chemical Engineering, had developed an early version of the sponge during her PhD at the U of T. Although the previous sponge removed more than 95 per cent of the oil in the samples tested, it took three hours to do so - far longer than would be useful in industry.

Acidity and alkalinity also presented an issue, as the pH of contaminated wastewater dictated how well the sponge worked. Dr Cherukupally said: "The optimal pH for our system was 5.6, but real-life wastewater can range in pH from four to ten. As we got toward the top of that scale, we saw oil removal drop off significantly, down to just six or seven per cent."

Now, Dr Cherukupally, together with U of T and Imperial academics, has chemically modified the sponge to be of potential use to industry. The new sponge works faster, and over a much wider pH range than the previous version.

The results are published today in Nature Sustainability.

Spongey secrets

To create the original sponge, Dr Cherukupally used ordinary polyurethane foams -- similar to those found in couch cushions -- to separate tiny droplets of oil from wastewater. The team carefully tweaked pore size, surface chemistry, and surface area, to create a sponge that attracts and captures oil droplets - a process known as 'adsorption' - while letting water flow through.

To improve the sponge's properties in the new study, Dr Cherukupally's team worked with U of T chemists to add tiny particles of a material known as nanocrystalline silicon to the foam surfaces. They could then better control the sponge's surface area and surface chemistry, improving its ability to capture and retain oil droplets - a concept known as critical surface energy.

After use, the sponge could be removed from the water and treated with a solvent, releasing the oil from its surface.

Dr Cherukupally said: "The critical surface energy concept comes from the world of biofouling research -- trying to prevent microorganisms and creatures like barnacles from attaching to surfaces like ship hulls.

"Normally, you want to keep critical surface energy in a certain range to prevent attachment, but in our case, we manipulated it to get droplets to cling on tight.

"It's all about strategically selecting the characteristics of the pores and their surfaces. Commercial sponges already have tiny pores to capture tiny droplets. Polyurethane sponges are made from petrochemicals, so they have already had chemical groups which make them good at capturing droplets.

"The problem was that we had fewer chemical groups than what was needed to capture all the droplets. I therefore worked with U of T chemists to increase the number of chemical groups, and with Imperial's Professor Daryl Williams to get the right amount of coating."

Oil cleanup

Co-author Professor Amy Bilton from U of T said: "Current strategies for oil spill cleanup are focused on the floating oil slick, but they miss the microdroplets that form in the water."

"Though our sponge was designed for industrial wastewater, adapting it for freshwater or marine conditions could help reduce environmental contamination from future spills."

Dr Cherukupally will continue to improve the sponge's performance for oil applications and has teamed up with Dr Huw Williams at Imperial's Department of Life Sciences to investigate how the sponges could remove bacteria from saltwater.

She also wants to use the sponges to treat contamination from gas, mining, and textile industries, and wants to make the technology affordable for use in developing countries - mainly for ridding contaminated rivers of organics, heavy metals, and pathogens.
-end-
This news story was adapted from a U of T press release.

Once the embargo lifts, the paper will be published here: https://www.nature.com/articles/s41893-019-0446-4

The previous paper is published here: https://pubs.acs.org/doi/full/10.1021/acs.est.7b01255

The research was funded by Natural Sciences and Engineering Research Council of Canada, Consortium of Cellular and Microcellular Plastics and Natural Resources Canada Oil Spill Response, Department of Fisheries and Oceans, Natural Sciences and Engineering Research Council of Canada, Engineering and Physical Sciences Research Council UK, and National Natural Science Foundation of China.

"Surface-engineered sponges for recovery of crude oil microdroplets from wastewater" by Pavani Cherukupally, Wei Sun, Annabelle P. Y. Wong, Daryl R. Williams, Geoffrey A. Ozin, Amy M. Bilton, and Chul B. Park. Published 16 December 2019 in Nature Sustainability.

Imperial College London

Related Wastewater Articles:

Wastewater test could provide early warning of COVID-19
Researchers at Cranfield University are working on a new test to detect SARS-CoV-2 in the wastewater of communities infected with the virus.
HKU team develops new wastewater treatment process
A University of Hong Kong research team has developed a novel wastewater treatment system that can effectively remove conventional pollutants, and recover valuable resources such as phosphorus and organic materials.
Treating wastewater with ozone could convert pharmaceuticals into toxic compounds
With water scarcity intensifying, wastewater treatment and reuse are gaining popularity.
Polluted wastewater in the forecast? Try a solar umbrella
Evaporation ponds, commonly used in many industries to manage wastewater, can occupy a large footprint and often pose risks to birds and other wildlife, yet they're an economical way to deal with contaminated water.
Wastewater leak in West Texas revealed
Geophysicists at SMU say that evidence of leak occurring in a West Texas wastewater disposal well between 2007 and 2011 should raise concerns about the current potential for contaminated groundwater and damage to surrounding infrastructure.
Mapping international drug use by looking at wastewater
Wastewater-based epidemiology is a rapidly developing scientific discipline with the potential for monitoring close to real-time, population-level trends in illicit drug use.
Mapping international drug use through the world's largest wastewater study
A seven-year project monitoring illicit drug use in 37 countries via wastewater samples shows that cocaine use was skyrocketing in Europe in 2017 and Australia had a serious problem with methamphetamine.
Plant research could benefit wastewater treatment, biofuels and antibiotics
Chinese and Rutgers scientists have discovered how aquatic plants cope with water pollution, a major ecological question that could help boost their use in wastewater treatment, biofuels, antibiotics and other applications.
Predicting earthquake hazards from wastewater injection
ASU-led geoscientists develop a method to forecast seismic hazards caused by the disposal of wastewater after oil and gas production.
Stronger earthquakes can be induced by wastewater injected deep underground
Earthquakes are getting deeper at the same rate as the wastewater sinks.
More Wastewater News and Wastewater Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.