Mechanism for the preparation of carbon spheres from potato starch treated by NH4Cl

Carbon spheres (CSs) retaining the morphology of potato starch were prepared by a two-step process: impregnation followed by carbonization. In this process, potato starch was impregnated in NH4Cl solution for 1h. The mechanism of preparation was proposed. The presence of HCl catalyzes the dehydration of impregnated starch at lower temperature than its melting point, which destroys the crystallites in original starch totally. This makes the microcrystalline melting difficult during the following carbonization. Scanning electron microscopy results show that small cavity exists in the center of sphere. The CSs shows high graphitization degree after graphitizing by X-ray diffraction analysis. (C) 2008 Elsevier Ltd. All rights reserved.