Green chemists turn cashew nut shells into sunscreen

A team of international scientists has found an environmentally friendly way of producing potential sunscreens by using cashew nut shells, a waste material.

A team of ‘green chemists’ from the University of the Witwatersrand in South Africa, along with colleagues from universities in Germany, Malawi and Tanzania, are working on techniques to produce useful compounds from wood and other fast growing non-edible plant waste, through a chemical process named xylochemistry (wood chemistry).

By using cashew nut shells, the team has produced new aromatic compounds that show good UVA and UVB absorbance, which may be applied to protect humans, livestock, as well as polymers or coatings from harmful rays from the sun. UV rays are damaging to most materials, and they can lead to sunburn, premature aging and even the development of potentially lethal melanomas in both humans and animals.

Until now, however, most UV filters made of organic and inorganic compounds are derived from petrochemicals. They also have a negative effect on marine ecosystems due to their poor biodegradability.

“With the current concerns over the use of fossil resources for chemical synthesis of functional molecules and the effect of current UV absorbers in sunscreens on the ecosystem, we aimed to find a way to produce new UV absorbers from cashew nut shell liquid (CNSL) as a non-edible, bio renewable carbon resource,” said Charles de Koning, of the Wits School of Chemistry and principal author of the paper, together with Till Opatz from Johannes Gutenberg University in Mainz, Germany.

“Cashew nut shells are a waste product in the cashew-farming community, especially in Tanzania, so finding a useful, sustainable way to use these waste products can lead to completely new, environmentally friendly ways of doing things.”

The team has already filed a patent application in order to commercialise the process in South Africa.

Image credit: Jenn Kosar via Unsplash

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