Kinetics of dissolution of zinc oxide in aqueous solutions of acetic acid

摘要

The laws governing the dissolution of zinc oxide in aqueous solutions of acetic acid by means of the rotating disk method are investigated. The influence of temperature (283-343 K), rate of rotation of disk (1.0-16.2 Hz), and concentration of acetic acid (0.6-150 g/dm~3) on the rate of dissolution of ZnO is considered. It is found that the process occurs in a compound regime. The values of the apparent activation energy for the kinetic and diffusion regimes are correspondingly 53 and 11 kJ/M. The order of the reaction with respect to concentration of acetic acid is equal to 0.8. Equations for both ZnO dissolution regimes in aqueous solutions of acetic acid that ensure satisfactory matching of the experimental and computed specific rates of the particular process are derived. An increase in temperature (T > 323 K) leads to a shift in the regime, with dissolution going from a kinetic to a diffusion regime. Diffusion limitations are related to the formation of a film of zinc acetate on the surface of the sample.