Mechanism and kinetics of wollastonite fibre dissolution in the aqueous solution of acetic acid

The dissolution of fibrous wollastonite (CaSiO3) in the aqueous solution of acetic acid (3 mol dm− 3) was investigated in the temperature interval from 25 to 50 °C using mixed batch-type reactor. An incongruent dissolution of wollastonite proceeds under applied acidic condition. The pH of solvent was increasing during leaching of calcium and its actual value depended on the concentration of Ca2+ ions in the solution according to the Henderson buffer equation. That enabled the monitoring of dissolution kinetics via concentration of Ca in the dispersion medium of suspension of wollastonite measurement. The kinetic parameter of the process was evaluated from measured dissolution rates of wollastonite at constant temperature using the empirical Arrhenius equation. The apparent activation energy and pre-exponential factor estimated from the Arrhenius plot are 47 ± 1 kJ mol− 1 and (1.8 ± 0.9) × 103 s− 1. The kinetics analysis of the process indicates that the process is driven by the stationary two-dimensional diffusion (D2).