Sponge cuts cleaning costs for oil spills

AN INTERCONNECTED ‘sponge’ structure made from polyurethane which can absorb oil, but let water flow through can be used as a cheaper alternative for cleaning oil spills.

Researchers from the Istituto Italiano di Technologia (IIT), Italy have developed a sponge made from polyurethane foam with a highly interconnected open porous structure that can soak in oil directly from the water.

The team has experimented with structures at laboratory scale, where the size of each pore is less than 500 µm. They found it was possible to reach oil absorption capacities of 30 g of oil per gramme of polyurethane.

Javier Pinto, materials scientist at IIT, said, “We wanted to understand what the key features of such foams are. Particularly whether it was necessary to modify the surface chemistry, or if a really good performance is reached simply by choosing foams with the right structural parameters.”

The current method of clearing an oil spill involves containing it with the use of floating booms and then 'sucking' the oil from the surface of the water.

The team has shown that altering the chemical functions of the porous structure did not appear to enhance the oil absorption efficiency. The absorbency appears to originate from the structure alone. This is why more expensive structures containing nanoparticles have not been able to outperform this standard.

“It came as a surprise that there is an absence of considerations of the structure or even characterisation of the foams. This is key to evaluating proposed treatments and coatings, and their effectiveness,” continued Pinto.

Pinto believes that the polyurethane foam can be scaled into a commercially-viable product suitable for oil remediation in the near future due to the simplicity of the sponge’s structure.

The next stage for the team will be to develop composite materials derived from plant waste that have biodegradable and biocompatible properties, further reducing the environmental impact of having to produce polyurethane. The team also hopes to develop a similar structure that can absorb heavy metal, or pesticide pollutions.

Applied Physics, DOI: 10.1088/0022-3727/49/14/145601