Morphological Characterization of Oxidized and Metal Impregnated Spherical Carbons

摘要

The surface of mi-croporous spherical carbon (S_(BET) = 1457 m~2/g, pH = 7.9) was modified by nitric acid treatment and by Cu~+, Cu~(2+) and Sn~(2+) salt impregnation. The morphology and the surface properties of the samples were characterized by SEM/EDS, low temperature nitrogen adsorption and small angle X-ray scattering. The surface chemistry of the samples was investigated under wet conditions. Oxidation by nitric acid changed the pH to 3.4 and slightly reduced the accessible porosity, but not the morphology or the Cu~(2+) adsorption capacity. Surface chemistry, morphology and the species of the anion and of the metal were found to influence the result of the impregnation. The most remarkable change occurred in the pore size range < 14 A due to pore blocking. This effect was a linear function of Cu~(2+) loading below the saturation capacity. When SnCl_2 was used instead of Cu~(2+) salts in aqueous phase, a redox reaction seemed to take place, resulting in greater surface roughness. Metal ions were not detected on the surface of the particles. Treatment with solid CuCl produced a practically complete CuCl film on the surface of the particles and metallic copper was formed as a by-product.