Thermal Stability and Surface Chemistry Evolution of Oxidized Carbon Microspheres

The surface activity of carbon microspheres (CMSs) can be significantly improved through oxidation reaction. To explore the changes of CMSs in the thermal stability and surface chemical properties, oxidized-CMSs were obtained with a mixture of concentrated sulfuric and nitric acids as the oxidizing agent. The characterization of morphologies, microstructures and thermal properties shows that oxygen-containing functional groups were introduced onto the surface of CMSs. The parent CMSs showed 4.99wt% weight loss in nitrogen atmosphere, which was mainly due to the evolution of carbon monoxide CO; oxidized-CMSs exhibited 30.97wt% weight loss, which was attributed to the thermal degradation of the oxygen-containing functional groups in the form of H2O, CO2, CO and NO, as examined by mass spectrometry.