A novel material could become the go-to solution for managing scary oil spills that can wreak havoc on the local ecosystem. Thanks to carefully tailored structure, the sponge-like material simply loves to soak in hydrocarbons being capable of absorbing 90 times its weight in crude oil.
Although there’s a downward trend in numbers of large oil spills, i.e. greater than 700 tonnes, these are still a major cause of environmental concern. BP’s 2010 spill in the Gulf of Mexico, for instance, spewed 2.5 million gallons of oil a day for months killing hundreds of birds and marine life, as well as the lives 11 crew members. The long-term effects on the Gulf’s fragile ecosystem, however, remain largely unknown — what’s certain is the area is devastated for years.
Cleaning an oil spill is never a pretty or easy job and two oil spills are alike due to variations in oil types, locations, and weather conditions involved. Typically, engineers would first start with containment using booms to confine the spill and skimmer equipment to collect the oil it from the water surface. Large quantities of dispersants are also dumped on the spill to break up the oil and speed its natural biodegradation. Additionally, there are commercially available sorbents specifically designed to absorb oil. These can be effective, depending on the situation, but their main drawback is that they have to be discarded immediately after use, just like you would throw away a paper towel soaked with last night’s mess from the kitchen.
Seth Darling and colleagues at the Argonne National Laboratory in Illinois wanted to make a sorbent that can be used more like a sponge than a paper towel. It consists of polyurethane foam coated with silane molecules which have a chemical affinity of liquid hydrocarbons. The foam, which is commonly found in everything from home insulation to cushions, is littered with ‘nooks and crannies’ where oil molecules can latch on to.
The challenge was to find just the right mix of silane since too little chemical interaction didn’t make the material absorbent and too much kept the oil trapped inside the foam.
They eventually reached a satisfying equilibrium and lab tests suggest the material, called the Oleo Sponge, can be soaked and have its contents squeezed multiple times without any noticeable loss in capacity.
To make sure, though, that these sponge can handle oil spills effectively, Darling and colleagues performed a large-scale test in a giant seawater tank in New Jersey called Ohmsett. The researchers submerged six-square-meter square pads made from Oleo Sponge into the pool, right behind a pipe that was spewing crude oil for the test. After the pads were well soaked, these were sent through a wringer to remove the oil. The process was repeated several times over a couple of days.
“The material is extremely sturdy. We’ve run dozens to hundreds of tests, wringing it out each time, and we have yet to see it break down at all,” Darling said.
All of the tests turned out very promising but the ultimate test is still the high seas. It’s not clear yet if Oleo Sponge can perform well under the high pressure of the deep sea. However, Oleo Sponge is definitely one of those innovative materials that look poised to make a lasting impact.