Kinetic analysis of mechanochemical reaction between zinc oxide and gamma ferric oxide based on the impact energy and collision frequency of particles

A new method for analyzing the rate of mechanochemical reactions using the kinetic energy and collision frequency of the reactive particles has been proposed based on the theoretical analysis of thermal chemical reactions. The rate constant of a mechanochemical reaction to form zinc ferrite through high-energy ball milling of a mixture of zinc oxide and gamma ferric oxide (maghemite) as the model mechanochemical reaction system was experimentally determined at several revolution speeds in a planetary mill. Based on the kinetic theory of molecules in a thermal chemical reaction, the kinetic energy of the particles was numerically determined from the velocity distribution of particles, which was obtained by a discrete element method (DEM) simulation of the particle and ball motion. The collision frequency of particles was also calculated and related to the kinetic energy according to the collision theory for molecules. Finally, the reaction rate constant was expressed as a pseudo-Arrhenius equation including a frequency factor and an energy factor as an alternative to the Boltzmann factor. Our method for analyzing the rate of mechanochemical reactions can contribute to precise control of their reaction rates. [Display omitted] •Kinetic energy of granule particle was determined by the velocity distribution.•Collision frequency of granule particle was expressed using the kinetic energy.•Rate constant of mechanochemical reaction was expressed as a pseudo-Arrhenius equation.