Abstract: Effects of particle size on kinetic parameters were studied by the reaction of nano-ZnO with solution of sodium bisulfate, and the cause of the apparent activation energy decreasing was discussed. The results show that the reaction rate is only related to the concentration of reactant when the particle size of reactant, the reaction temperature and the stirring rate are constant. The particle size has obvious effects on the reaction order, the rate constant, the activation energy and the pre-exponential factor. With decreasing the particle size, the rate constant and the reaction order increase, while the pre-exponential factor and the apparent activation energy decrease. There is a linear relation between the apparent activation energy and the reciprocal of the size, and the particle size exerts influences on kinetic parameters of a heterogeneous reaction through the mole surface area, the mole surface energy and the mole surface entropy.

Key words: Nanoparticle, ZnO, Heterogeneous reaction, Rate constant, Activation energy, Reaction order, Pre-expotential factor