Naslov
Vaterite Growth and Dissolution in Aqueous Solutions. I. Kinetics of Crystal Growth

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

Izvornik
Journal of crystal growth (0022-0248) 104 (1990), 4; 793-800

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

Ključne riječi
calcium carbonate ; vaterite ; calcite

Sažetak
The kinetics of precipitation of vaterite (CaCO3) from aqueous solution between about 10 and 45°C and at ionic strengths from 15mM to 315mM was determined by recording pH as a function of time and analysing these data by a BASIC computer program, correcting for complexes and using activity coefficients. The particles were spherulites with diameters less than 5 μm, and the growth kinetics parabolic, with the rate constants (dr/dt)/(S-1)2 equal to 0.180, 0.468, 0.560, 1.250 and 1.860 nm/s at 11.4, 21.7, 25.0, 33.8 and 42.5°C, respectively, and 0.560, 0.588, 0.594 and 0.610 nm/s at ionic strengths 15mM, 65mM, 115mM and 315mM, respectively. The change with temperature corresponds to the activation energy, 57.1 kJ/mol. It is shown that the rate constants found are in quantitative agreement with those calculated from the theory of growth of electrolyte crystals from aqueous solution. This means that the rate- determining mechanism is the release of water molecules from the calcium ions as they “jump” into lattice positions.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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