Making Bio-lubes from Cashew Shells


Making Bio-lubes from Cashew Shells
Black in color, cashew nut shell liquid is extracted during the process of obtaining the cashew nut kernel. Photo by Viktor Braga/UFC

Creating bio-lubricants using the liquid by-product extracted during processing of cashew nuts is the subject of a new patent earned by Brazil’s Federal University of Ceará, Agência UFC reported last week. The liquid consists mainly of a phenol-type compound that reduces friction between metals.

The UFC agency previously released reports on the liquid’s use in the generation of other products, including insecticides, antimicrobials and antifungals. The agency noted that the use of vegetable oils in bio-lubricants can run into concerns in terms of its production coming into conflict with agricultural and food sectors because of the need for large areas for planning raw material and high economic or social costs.

Under the patent, the lubricant obtained by using the cashew nut shell liquid is presented as an alternative because it is a by-product normally extracted during the processing of cashew nuts to obtain the kernel – the main objective of the cashew crop industry. “As it is already inserted in a well-established production process, the use of [cashew nut shell liquid] circumvents the problems of costs and conflicts presented by vegetable oils,” Agência UFC said in its report.

The UFC agency explained that the cashew nut shell liquid works as a raw material for producing bio-lubricants because it consists primarily of a phenol-type compound – cardanol – which adheres to metallic surfaces in a compact way, creating a film that helps reduce friction and wear caused by the contact between metals.

Under the patent, a molecular distillation process obtains cardanol in high purity, removing other existing components in the cashew nut shell liquid that may interfere with the chemical synthesis process, explained Professor Selma Mazzetto, coordinator of the Laboratory of Products and Technology in Processes of the UFC and one of the inventors who signed the patent.

“The main object of the new patent is precisely the production of bio-lubricants from these reactions that can be considered ecologically correct, with a production process with less polluting waste and with the use of materials that are less harmful to the environment,”  Agência UFC said in its report.

Mazzetto noted that development of the cashew nut shell liquid product as a raw material for bio-lubricants takes advantage of the strength of Brazil’s chestnut industry, especially in Ceara. “The great advantage of producing and using these bio-lubricants is related to the appreciation of an input of regional origin, of which Ceará is the largest producer, and which currently does not have a noble application,” she said. “With the development of this type of technological product, we can expect a great socioeconomic impact for our region.”

Researchers estimate that around 10 kilograms of cashew nuts are needed to obtain one liter of the by-product liquid, the professor said, noting that the synthetic route for obtaining bio-lubricants from the by-product liquid indicates yields of around 80-90%, depending on the bio-lubricant type.