Naslov
Vaterite growth and dissolution in aqueous solution II. Kinetics of dissolution

Autori
Kralj, Damir ; Brečević, Ljerka ; Nielsen, Arne Erik

Izvornik
Journal of crystal growth (0022-0248) 143 (1994), 3-4; 269-276

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
calcium carbonate ; vaterite ; precipitation kinetics ; dissolutin kinetics

Sažetak
The kinetics of dissolution of vaterite (CaCO3) crystals in aqueous potassium chloride solutions were studied at temperatures between 15 and 45 deg. C and ionic strengths between 50 and 200 mol/L. The vaterite precipitate used consisted of spherulites of vaterite crystals with initial radii of 2.7 to 4.6 um. The progress of the dissolution was folllowed by recording pH as a funcito of time. From pH the concentration of the dissolved matter was calculated, and from this we found the particle size, r, and the dissolution rate, -dr/dt, where r=average particle radius and t=time. Straight lines were obtained by plotting - r(dr/dt) as a function of undersaturation, which may be explained by diffusional rate control. Both the values of the appaarent diffusion coefficients determined and their dependence on temperature (activation energy = 24.38 kJ/mol) support the assumption that the rate-determining process for the dissolution is the diffusion of the hydrated calcium and carbonate ions away from the crystal surface into the bulk solution.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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