An alternative for cocoa pod husk delignification using hydrogen peroxide

Abstract

The cocoa pod husk (CPH) is a by-product that represents around 76 % of the fruit. The cellulose, lignin, and hemicellulose content of the CPH was analyzed, and then the response surface methodology was used to carry out a CPH delignification process with H₂O₂ at different concentrations, temperatures, and treatment times. The results showed that CPH was composed of 20.95 %, 7.9 %, and 20.4 % (dry basis) cellulose, hemicellulose, and lignin, respectively. The delignification treatment achieved a removal rate of 73 % for lignin, 30.3 % for hemicellulose, and 17.6 % for cellulose (values very close to the statistically estimated values). Analysis in the mid- and near-infrared region showed the characteristic signals of lignin, hemicellulose, and cellulose, allowing the reduction of their signals in the characteristic bands to be visualized. It is concluded that the H₂O₂ delignification method allows for high lignin removal comparable to that of traditional methods. Finally, the environmental impact analysis performed with the waste reduction algorithm found that increasing hydrogen peroxide concentration in CPH delignification significantly elevates atmospheric and toxicological environmental impacts; it is therefore suggested to optimize the use of this reagent.