Super Absorbing Polymer Soaks Up Oil Spills

In the spring and summer of 2010, the world watched as the Deep Water Horizon/BP oil spill spewed hundreds of millions of gallons of crude oil into the Gulf of Mexico. Efforts to collect or disperse the oil were largely futile. Booms deployed on the surface to contain the oil were ineffective when waves overtopped the booms. The oil that was collected was mixed with much greater amounts of sea water. Burning the oil produced clouds of toxic smoke. The final method, injecting chemical dispersants into the oil plumes, multiplied the toxicity to marine life by orders of magnitude.

Mike Chung, a Penn State materials scientist, was as riveted by the unfolding drama as the rest of the world. “It was a disaster,” he recalls. “There was no solution.”

Chung had worked as a scientist for the Exxon Corporation during the time of an earlier disaster, the grounding of the Exxon Valdez on a reef in Prince William Sound in Alaska in March 1989. The oil ended up coating 1,300 miles of coastline and 11,000 square miles of ocean. Even after almost thirty years, if you dig a few inches into the shore, oil will still seep up out of the sand.

Exxon, too, tried using dispersants, but they were too toxic and eventually, Chung says, they cleaned up what oil they could with the equivalent of paper towels and left the rest. Although the Exxon Valdez oil spill was a major disaster that effected the livelihood of thousands of fishermen, it is ranked as only the 36th largest oil spill on record.

As he watched the BP disaster unfold, Chung asked himself how materials science could help, how he could help. In 2010, he and his research group began to work on the problem.

The making of Petrogel

Despite advances in so many other fields of modern science, the same largely ineffective methods for cleaning up oil spills are still in use today as at the time of the Exxon Valdez disaster: capturing the oil in booms, burning the oil, or using dispersants to break up the oil to be consumed by microbes. All of these were tried in the Gulf, with mixed success. It is estimated that less than 25 percent of the oil was recovered, and that oil was a mixture that contained 90 percent seawater.

Chung envisioned a synthetic material that could absorb oil while rejecting water. He thought of it as a super absorbing polymer (SAP) similar to hydrogel, the SAP material used in diapers. Only his SAP would be designed to absorb hydrocarbons with different compositions.

“We are polymer chemists,” says Chung. “We can use a component from oil – polyolefin – that has a natural affinity for oil.”

Petrogel can be made in the form of powder, flakes, or as a film. As it soaks up oil molecules, it turns into a gel. Within two hours, the oil/Petrogel mixture can expand 30 times. Within 24 hours, it will expand 40 times. In comparison, the best oil absorbant material on the market can only absorb 10 times its weight in 24 hours, and it is far more expensive than Petrogel is projected to be, Chung says. In addition, the fast absorption kinetics allows Petrogel to absorb the oil before evaporation.

One pound of Petrogel is expected to cost about $2, but can recover 6-7 gallons of oil. Even at $30 per barrel, Petrogel can collect more than enough reusable oil to pay for itself twice over. Unlike other oil absorbing materials, Petrogel can itself be converted to oil at a temperature of 350 degrees C, well below the 600 degrees C temperature of typical oil refining. Under mass spectroscopy, recovered oil and crude oil look the same, says Chung.

Undergoing testing

The Bureau of Safety and Environmental Enforcement is an agency of the Department of the Interior charged with regulating the safety and overseeing the oil-spill response plans of the off-shore oil industry on the U.S Outer Continental Shelf. The BSEE works closely with sister agencies such as the U.S. Coast Guard and the Environmental Protection Agency to develop technologies and capabilities to enhance oil-spill response.

In fall 2015, BSEE tested Petrogel in small 10 x10 foot tanks tank at their Ohmsett research facilities in Leonardo, New Jersey, using Alaskan North Slope crude oil. In the BSEE funded project, two types of Petrogel were studied for viscosity change and basic rheology – how a fluid flows and spreads. This will determine how well the oil/Petrogel mixture will flow in mechanical pumping.

The testing showed that both mixtures of the polymer Petrogel absorbed more than 30-40 times its weight in oil within two hours. Mechanical testing showed that fluid recovery from the water’s surface was possible using a skimmer, either with or without a pump attached.

The next step is to do a simulation under arctic conditions. This testing will take place in Ohmsett’s mile-long 2.6 million-gallon salt water testing tank in December 2016. In this tank, waves and frigid weather will simulate conditions in the Arctic Ocean. Chung is still working to scale up to the 250 lbs. of Petrogel the testing will require.

Just the beginning

Crude oil from different parts of the world are different from each other. Chung’s team designs formulations specific to a particular type of oil. His designs work well with both Alaskan and Gulf oil, but work even better with refined oil. He believes the possibilities for cleanup extend to most any type of hydrocarbon.

“This is just the beginning,” he says. “Hydrogel was first developed for disposable diapers. Now it has expanded to many applications. We think Petrogel will be similar.”

There are oil spills all of the time, he points out. Pipelines spring leaks, oil or gas spills on the highway or in train derailments, gas stations leak oil. Refineries have dirty water that could be cleaned up using Petrogel, and hydrocarbons leak into streams and rivers from farm runoff.

“The properties are there – they can be used in many ways,” he points out.

An unusual application he has been thinking about involves natural gas separation. Natural gas from underground is composed of different types of hydrocarbons – the most important of which is methane (C1) – that need to be separated through a series of treatments. The current cryogenic method involves lowering the temperature of all components of the gas to minus 150 degrees C. The first gas to boil out is C1or methane. Lowering to that temperature is a very energy intensive proposition. Chung envisions using pressure combined with gradually lowering temperature to boil off the other gases until at around 0 degrees C, only methane remains. A few early lab experiments seem to indicate this approach might work, possibly saving industry the cost of big cryogenic facilities and the accompanying energy costs.

“It’s not enough to just write papers,” says Chung. “If you want to have a real societal impact you have to get your ideas into the marketplace.” Chung and Penn State have two patents, one that is pending, on Petrogel, as well as a trademark on the product name. He is seeking the kind of funders who could help him scale up his technology to make Petrogel as common a material as hydrogel, available wherever in the world oil is spilled.