Oil's well that ends well

Sushanta Kumar Sahoo's lab develops biodegradable polymers for use in the packaging industry. For the past few years, he and his team have been working on a plant oil-based material that can be coated on paper-based packaging to make it moisture- and oil-resistant. But the high and fluctuating costs of soya bean oil, the starting material, prompted them to look at another material — waste cooking oil (WCO), or edible oil after a few cycles of frying.

When the idea first struck Sahoo and the team at the CSIR-National Institute for Interdisciplinary Science and Technology in Thiruvananthapuram, Kerala, they didn't have to look hard for WCO: it was available in large quantities at the institute canteen. The team worked on used sunflower oil taken from its kitchen. With this waste oil, they have now produced a coating material which, when applied to paper, makes it moisture- and oil-resistant in hot or cold conditions. Additionally, the coating can easily be removed in an alkaline environment and composted in a vermicomposting environment under ambient conditions.

Much of current-day paper-based packaging comes lined with a thin plastic sheet to make it water-resistant. The plastic sheet makes the packaging material difficult to degrade and compost. "The beautiful thing about the (WCO) coating is that it can compete with plastic-lined paper as a packaging material while also being completely re-pulpable," Sahoo says. He and his colleagues published their findings (bit.ly/fry-oil) in ACS Sustainable Resource Management in 2024.