Kinetic study of uranium removal from aqueous solutions by macauba biochar

Abstract

Macauba (Acronomia aculeata) is a palm tree native of the Brazilian “cerrado” and a valuable renewable source of vegetable oil for human consumption and biodiesel production. Residue from the extraction of the coconut oil, the shell, or endocarp, can be used as a raw material for the production of biochar (BC) aiming the removal of uranium from aqueous solutions. Biochars are obtained by thermal decomposition of the biomass under inert atmosphere (pyrolysis) and, because of their surface properties and porous structure, they exhibit great potential as adsorbents. Adsorption of U(VI) was studied by a batch technique using a biochar produced through slow pyrolysis at 350°C of the macauba endocarp. The effect of contact time was investigated and a kinetic study was conducted to determine the mathematical model that best describes the adsorption process. The adsorption capacity (qmax) obtained for BC350 was 405 mg g-1.