Recyclable bioplastic membrane could clear devastating oil spills

A new bioplastic membrane can separate water and oil before being recycled and reused, a potentially important breakthrough in cleaning up devastating oil spills.

The polymer membrane was developed by researchers at the University of Groningen and NHL Stenden University of Applied Sciences, both in the Netherlands.

Made from a bio-based malic acid, it is a ‘superamphiphilic vitrimer epoxy resin membrane’. When the pores are blocked it can be depolymerised, cleaned and pressed into a new membrane.

Superamphiphilic membranes are a promising solution for oil spills but have not yet been very practical, the researchers said. The membranes are often not robust enough for use outside the laboratory environment, and the membrane pores can clog up with algae and sand.

In recent years, the researchers from both institutes joined forces to investigate vitrimer plastics, polymer materials that have the mechanical properties and chemical resistance of a thermoset plastic. Vitrimer plastics can also behave like a thermoplastic, meaning they can be depolymerised and reused. This means a vitrimer plastic has all the qualities to make a good membrane for oil spill remediation, the team said. The polymers are ground into a powder by ball milling and turned into a porous membrane through the process of sintering.

Both water and oil will spread out on the resulting superamphiphilic membrane. In an oil spill, much more water is present than oil, which means that the membrane is covered by water that can then pass through the pores.

“The water film on the membrane's surface keeps the oil out of the pores so that it is separated from the water,” said Vincent Voet from NHL Stenden.

The membrane is firm enough to filter oil from water, and can be recycled after removing pollutants and becoming clogged with other substances.

“We have tested this on a laboratory scale of a few square centimetres,” said Katja Loos from Groningen. “And we are confident that our methods are scalable, both for the polymer synthesis and for the production and recycling of the membrane.”

The team hope an industrial partner will further develop the project.

The research was published in Advanced Materials.