Ozone Reaction with Carbon Nanostructures 2: The Reaction of Ozone with Milled Graphite and Different Carbon Black Grades

Synthetic graphite particles 0.2 microns in diameter react with O₃ at room temperature with evolution of CO₂. Graphite is less reactive with ozone than carbon blacks having different surface area ranging from 120 to 8 m²/g, but graphite reactivity is comparable to that shown by powdered solid C₆₀ and C₇₀ fullerenes. The kinetic rate constant derived from the ozone consumption k appears in relation with the rate of CO₂ evolution suggesting a very simple reaction stoichiometry at the early stages. The reaction between ozone and graphite or carbon blacks essentially involves two stages: the gasification of the surface to CO₂ and its functionalization with oxygenated chemical groups, mainly as COOH but also other oxygenated chemical moieties. The pseudofirst order kinetics appears adequate to describe the heterogeneous reaction between ozone and the selected carbon materials. The discussion of the results is focused on the role played by fullerene-like carbon nanostructures, present in graphene sheets to explain the observed gasification rates and surface functionalization.