Abstract
Three biochars issued from raw or pretreated cashew nut shell were produced at 400, 600 and 800°C under nitrogen by pyrolysis in inert atmosphere. The specific surface area developed by these biochars were between 145 and 306 m²/g depending on biomass (raw or pretreated shell) and pyrolysis temperature. The increase of pyrolysis temperature leads to an increase in biochar porosity and the biochars were microporous materials.The carbon contain of these different biochars ranged between 70 and 87 % depending on pyrolysis temperature.The pH of these three carbonaceous materials were basic between 9 and 11. When produced at 400, 600 and 800°C, the biochars yields were 25, 22 and 20 % respectively. Biochars produced at 800°C had the best adsorption capacity of mycotoxins (aflatoxins and ochratoxin A) in aqueous solutions. Modeling with the Freundlich and Langmuir equations made it possible to understand the adsorption mechanism of aflatoxins and ochratoxin A respectively. The adsorption kinetics of both mycotoxins follow the pseudo-second order kinetic model. The study of interactions between biochar and toxigenic molds (Aspergillus carbonarius and Aspergillus parasiticus) revealed that biochar had no influence on them.