COMPARATIVE ANALYSIS OF DISSOLUTION KINETICS OF Ca, Mg, Fe, AND Mn carbonates
The search for effective methods of cleaning heating surfaces from precipitation of metal carbonates requires careful study of dissolution kinetics of the following elements: carbonates of calcium, magnesium, iron and manganese. There conducted a comparative analysis of kinetic curves of the powdered samples’ dissolution in hydrochloric acid. It is established that with increasing pH from 2 to 5 the rate of Ca, Mg, Fe, and Mn carbonate dissolution decreases drastically. In pH range from 5 to 10, the dissolution rate does not depend on the concentration of H+. At pH greater than 10 there is a further decrease in the rate of the process. It is established that in acidic and neutral environments, the mechanism of carbonate dissolution is different. The orders of the reaction rate by H+ in pH range from 1 to 5 were revealed. The dependence of the Ca, Fe, and Mg carbonate dissolution rate on temperature was studied experimentally; the values of the activation energy were calculated using the Arrhenius equation. It is established that the logarithm of the dissolution rate is linearly dependent on the logarithm of solubility. The decrease in dissolution rate of the investigated carbonates was ranged as follows: CaCO3>FeCO3>MnCO3>MgCO3.