Researchers Unveil the Potential of Cocoa Pod Husks as Flame-retardant Material

Millions of cocoa pods are harvested annually, while the beans and pulp go to make chocolate, their husks are thrown away.

Researchers reporting in ACS #SustainableChemistry & Engineering show that cocoa pod husks could be a useful starting material for #flameretardants.

Renewable Replacement for Petroleum-based Substances:

It’s estimated that about 24 million tons of leftover cocoa pod husks are produced yearly. #Wastehusks have been explored as a source of carbohydrates and sugars, but they also contain lignin, a tough #lipidpolymer found in many #woodyplants.

And lignin could be a renewable replacement for some substances typically derived from petroleum, such as flame retardants. While most methods to produce lignin have centered on hardwood trees, some scientists have processed other plant materials that would otherwise go to waste, such as rice husks and pomegranate peels.

Nicholas J. Westwood and coworkers wanted to see if high-quality lignin could be extracted from cocoa pod husks and determine whether it has the potential to make valuable, practical materials. The researchers obtained cocoa husks and milled them into a powder. After rinsing to remove fatty residues, they boiled the powdered husks in a mixture of #butanol and acid, a standard lignin extraction method called the butanosolv process. They next confirmed the isolated lignin’s quality and high purity, finding no evidence of carbohydrates or other contaminants.

Then, over the course of three chemical steps, the team modified the pure lignin biopolymer to have flame-retardant properties. They attached 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which is a fire suppressant molecule called DOPO, into the backbone of the #lignin polymer. In experiments, when the modified lignin was heated, it charred — but did not burn up — a sign that it could act as a flame retardant. The researchers recognize that human safety tests are important and plan to conduct them after the next phase of testing. In the future, the researchers say they will optimize the properties of their #cocoapodhusk-based flame-retardant materials.

Source: American Chemical Society/specialchem

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