Cocoa pods – source of chocolate and possible flame retardant

As Halloween approaches, anticipation for trick-or-treating grows, and with it, the annual harvest of millions of cocoa beans used to make delightful chocolates. However, amidst the production of chocolate, the shells of these beans are discarded. Now, researchers unveil the potential of cocoa pod shells as a valuable starting material for flame retardants.

It is estimated that approximately 24 million tons of cocoa pod shell residues are generated annually. While these shells have been explored as sources of carbohydrates and sugars, they also contain lignin, a robust lipid polymer found in many woody plants. Lignin can serve as a renewable alternative to certain substances derived from petroleum, such as flame retardants. While most lignin production methods focus on broadleaf trees, some scientists have processed other plant materials that would otherwise go to waste, such as rice husks and pomegranate peels. Hence, the interest in extracting high-quality lignin from cocoa pod shells and determining its potential for creating valuable, practical materials.

Researchers obtained cocoa pod shells and ground them into powder. After rinsing to remove residual fats, the powdered shells underwent a standard lignin extraction method known as the butanol-solvent process. Subsequently, the team confirmed the quality and high purity of the separated lignin, with no evidence of carbohydrates or other contaminants.

Three chemical steps

In a series of three chemical steps, the research group modified the pure lignin biopolymer to impart flame retardant properties. They introduced 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (a flame retardant molecule known as DOPO) into the main chain of the lignin polymer. In experiments, when the modified lignin was heated, it charred – but did not combust – indicating its potential as a flame retardant. The researchers emphasize the importance of human safety testing, with plans to conduct tests in the next phase. Future endeavors involve optimizing the performance of flame retardant materials based on cocoa pod shells.

This innovative approach not only repurposes waste from the cocoa industry but also opens doors to sustainable, eco-friendly flame retardant solutions. The journey from cocoa pod shells to valuable materials showcases the potential for transforming agricultural by-products into environmentally conscious innovations.

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