NewsLaser-treated cork: A revolutionary method to combat oil spills
Laser-treated cork: A revolutionary method to combat oil spills
25 April 2024 09:07
Scientists from China and Israel have found a way to remove petroleum oil from seawater and oceans using cork treated with a laser.
Researchers from Central South University and Huazhong University of Science and Technology in China and Ben-Gurion University of the Negev in Israel have used natural cork subjected to laser treatment to clean seawater following oil spills. Their findings were published in the respected journal "Applied Physics Letters" by the American Institute of Physics.
Traditional methods for cleaning waterways from oil spills have included using absorbent brush systems, deploying preparations with "oil-eating" bacteria, burning off the liquid fuel stains, or spraying them with chemicals. However, these methods were either too expensive, not very effective, or harmful to the environment.
The answer is simply cork
To address these challenges and find a non-toxic, effective solution with a low carbon footprint, the researchers turned to cork, a natural resource harvested from cork oak bark.
"We discovered in a particular laser experiment that the wettability of cork significantly changed under the influence of laser light. The material became superhydrophobic (water-repelling) and superoleophilic (oil-attracting)," explained Yuchun He, the study's lead author from the Department of Physics and Electronics at Central South University.
"Cork is environmentally friendly and recyclable, making it ideal for oil spill removal," added Kai Yin, co-author of the study.
Cork oaks are evergreen trees grown in North Africa and southern Europe. The bark can be safely harvested around every seven to nine years, which encourages the trees to absorb more carbon dioxide as they increase their biological activity to regenerate, thus helping reduce greenhouse gas levels in the atmosphere.
In their research, the scientists explored various laser treatments on cork, examining its nanoscopic structure changes, composition, and how water and oil interact with its surface. They also tested the durability of cork against many heating and cooling cycles by evaluating its absorption, reflection, and emission of light waves across the spectrum.
After being laser-treated, cork gains unique photothermal properties
When exposed to sunlight, the material heats up rapidly—within 10-15 seconds to around 60 degrees Celsius. Interestingly, when this treated cork is introduced into contaminated seas, it causes the petroleum oil on the water's surface to heat up, reducing its viscosity and making it easier to collect.
Yin explained, "Rapid pulsed laser treatment roughens the cork's surface microstructure, enhancing its hydrophobicity from micro to nano level."
As a result, the treated cork doesn't absorb water but attracts petroleum oil. In tests, the material absorbed about 4 grams of oil per 6.5 square centimetres in 200 seconds. The researchers noted that the oil could be recovered from the bark, and the material could be reused for cleaning water.
Oil spills, caused by drilling platform leaks, tanker accidents, or pipeline ruptures, are among the most catastrophic ecological disasters. They result in multimillion-dollar financial losses and pose a deadly threat to marine ecosystems, affecting them for years. Particularly, they harm life in coastal zones, and when oil contaminates soil, surface, and groundwater, land organisms, including humans, are also at risk.
The largest such disaster in history happened in the Gulf of Mexico in April 2010, following an explosion on the Deepwater Horizon drilling platform. The leak lasted 87 days, releasing about 770 million litres of oil into the bay, impacting the southern coast of the USA. It is estimated that up to a million seabirds and hundreds of thousands of fish, whales, dolphins, and sea turtles may have died, causing irreversible damage to the ecosystem of the northern Gulf of Mexico.
