A researcher from the University of Bath in the U.K. has identified that molecules locked within orange peel could be used as building blocks in products such as pharmaceuticals and plastics – helping break our reliance on crude oil.
Writing for TheConversation.com, an academic and research community, post doctoral researcher Marc Hutchby explained how chemicals in the citrus fruit, most of which are discarded in the current highly wasteful juicing processes, could potentially replace crude oil in products.
As much as 95 percent of the oil extracted from waste rinds is made up of limonene molecules, also known as C10H16, a colorless liquid hydrocarbon. This hydrocarbon shares many similarities with the chemicals we obtain from fossil fuels, such as its liquid nature and boiling point, said Hutchby.
“Therefore the technology we currently use on petrochemical feedstocks can be directly used on limonene to turn it into useful products. We can do this by exploiting limonene’s two carbon double bonds for a variety of chemical transformations.”
The “greatest potential” is as a building block for the polymer industry, replacing fossil fuels in products such as polypropylene fibers used in carpets, or polyethylene for plastic bottles. It could also be used in the production of paracetamol, using limonene’s carbon skeleton at its core.
With an estimated 20 million tons of citrus being wasted each year, repurposing this waste could yield approximately 125,000 tons of limonene a year.
However, these are just the first steps, said Hutchby. There are a number of challenges to overcome, including finding a reliable supply and greener processing of the fruit. Hutchby’s research team is currently investigating how to modify bacteria to feed off municipal waste and excrete limonene as their only product.