The comparison of the inactivation rate of SARS-CoV-2 by ozone in water with that in gas, based on data from references and experiments, has indicated the inactivation rate of the former is remarkably higher than that of the latter. To investigate the reason for this difference, we analyzed the reaction rate using a diffusional reaction model, in which ozone is carried by micro spherical viruses to inactivate the target viruses. Using this model, we can evaluate the amount of ozone required to inactivate a virus based on the ct value. We found that inactivation in gas phase requires 1014-1015 ozone molecules per virus virion, while the inactivation in aqueous phase requires 5×1010 to 5×1011 ozone molecules. This implies that the efficiency in gas phase is 200-20,000 times lower than that in aqueous phase. This is not attributed to the lower probability of collision in gas phase than in aqueous phase. Rather, it may be due to the fact that the ozone and radicals generated by ozone react and subsequently dissipate. We proposed the diffusion of ozone into a spherical virus at a steady state and the decomposition reaction model through radicals.
Keywords: coronavirus disinfection with ozone; ozone transport in gas phase; ozone transport in liquid phase; radical formation; radical scavenger.