Naslov
Effects of initial supersaturation on spontaneous precipitation of calcium carbonate in the presence of charged poly-L-amino acids

Autori
Njegić-Džakula, Branka ; Falini, Giuseppe ; Brečević, Ljerka ; Skoko, Željko ; Kralj, Damir

Izvornik
Journal of colloid and interface science (0021-9797) 343 (2010), 2; 553-563

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

Ključne riječi
calcium carbonate ; calcite ; vaterite ; amorphous calcium carbonate ; spontaneous precipitation ; acidic poly-L-amino acids

Sažetak
Spontaneous precipitation of calcium carbonate was investigated in two precipitation systems: (1) with initial supersaturation lower than that corresponding to the solubility of amorphous calcium carbonate (ACC), at which vaterite precipitated, and (2) with initial supersaturation higher than that of ACC solubility, at which a mixture of calcite and vaterite was formed. After the addition of an acidic polypeptide, poly-L-glutamic acid (pGlu) or poly-L-aspartic acid (pAsp), into (1) a significant inhibition of nucleation, expressed as an increase in induction time, and growth of vaterite, perceived as a dead zone, was observed. Extent of inhibition decreased in the order: InhpAps > InhpGlu > InhpLys. The addition of a polypeptide into (2) caused the inhibition of precipitation and changed the morphology and polymorphic composition of the precipitate ; only vaterite appeared at approximately cpAsp = 3 ppm, cpGlu = 6 ppm, or cpLys = 7 ppm. This finding is explained as a consequence of kinetic constraints through the inhibition of calcite nucleation and stronger binding of acidic polypeptide by the calcite surfaces than by the vaterite surfaces. Laboratory precipitation studies using conditions that resemble those in living organism should be run at an initial supersaturation corresponding to the solubility of ACC as a limiting condition.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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