Modified sponge could pick up petroleum contaminants from arctic waters

Researchers have developed a sustainable and economical way to recover oil from ultra-cold industrial wastewater and oil spills.

Scientists at Imperial College London and the University of Toronto have designed a sponge capable of removing hard-to-recover oil from Arctic waters. Their research draws on previously developed sponge technology to target specific challenges with oil recovery from ultra-cold water.

The results, published in Scientific progress, present an economical and sustainable method of oil recovery that will benefit the environment while presenting a cost effective solution to industry.

Oil contamination in the Arctic

Researchers have developed a special coating for commercially available sponges that can catch oil droplets from water as cold as 5 degrees Celsius. Oil is more difficult to remove from ultra-cold water because it becomes viscous at low temperatures, which reduces its flow and makes it more difficult to collect.

Oil contamination in arctic waters is a significant problem, with more than a trillion liters of tar sands tailings, a byproduct of oil extraction, marine and arctic oil spills awaiting cleanup .

The traditional technologies used to recover oil from these sites are either energy intensive, expensive or inefficient when dealing with oil droplets of micrometric size. Some may even risk causing additional environmental damage, such as those that heat the oil before collection, which can dissolve or evaporate.

The technology engineered by Imperial and U of T addresses these challenges by harnessing the properties of cold-temperature petroleum to create a low-energy, cost-effective solution. Not only will this benefit the environment and help protect our natural resources, it will provide an economically viable solution for the industry that is vital to ensuring widespread adoption.

Mutual attraction

The Imperial team has designed a special coating for commercially available sponges based on the behavior of oil droplets in cold water.

When the oil is below 38 degrees Celsius, it starts to crystallize and becomes sticky around the edges. Lead author Dr Pavani Cherukupally used this knowledge to design a paraffin-like sponge coating with the same chemical structure as oil which could create mutual attraction between the two surfaces.

The sponge can be rinsed with a non-toxic solvent which displaces the sticky oil droplets and allows them to be collected, allowing both the sponge and the oil to be reused. The process is known as wax wetting, where one fluid is used to move another. In this case, the solvent, called heptol, is used to displace the oil droplets.

Once the optimal wetting characteristics of the wax were established, a team of chemists from the University of Toronto synthesized the nanocoating which made it functional and ready for use on a larger scale.

Rigorous testing has shown that the technical sponge can adsorb oil droplets from water between 5 and 40 degrees Celsius and remove 90 to 99% of contaminants in two and a half hours. The recovered oil can be reused by industry, providing an economic benefit to organizations, and the sponge can be reused ten times with consistent results.

Next steps

This method of oil recovery has significant advantages for both industry and the environment. It has a high success rate of removing oil from ultra-cold water and does not require any additional energy input as it uses the material properties of the sponge and oil to generate results.

Lead author Dr Pavani Cherukapally, Imperial College London, explained: “We have developed an energy efficient way to recover crude oil that has ecological benefits for the environment and is economically beneficial for the environment. industry.

“Our work is important because it targets a specific problem, low temperature oil crystallization, and addresses it from a materials perspective.”

Principal Investigator Professor Daryl Williams added: “If we continue to treat the environment as we have for decades, clean water will become increasingly scarce. As such an important global resource, it is vital that society and industry have access to innovative and inexpensive resources. water purification methods such as those reported in our study.

“Our technology heralds a new approach to comprehensive remediation that we hope will be widely used before it’s too late.”

Next, the team will explore how the sponge can be used to collect a range of oils, each of which has a different composition and behaves differently at low temperatures. They believe their sponge technology can be adapted to meet these different needs under many different environmental conditions.