Crystal growth of calcite

The crystal growth of calcite has been studied by Plummer and coworkers (1978), by Kunz and Stumm (1984) and by Chou and Wollast (1989) to correspond to the backward rate of dissolution (Eq. 8.3). 

Calcium phosphate precipitation may also be involved in the fixation of phosphate fertilizer in soils. Studies of the uptake of phosphate on calcium carbonate surfaces at low phosphate concentrations typical of those in soils, reveal that the threshold concentration for the precipitation of the calcium phosphate phases from solution is considerably increased in the pH range 8.5 -9.0 (3). It was concluded that the presence of carbonate ion from the calcite inhibits the nucleation of calcium phosphate phases under these conditions. A recent study of the seeded crystal growth of calcite from metastable supersaturated solutions of calcium carbonate, has shown that the presence of orthophosphate ion at a concentration as low as 10-6 mol L" and a pH of 8.5 has a remarkable inhibiting influence on the rate of crystallization (4). A seeded growth study of the influence of carbonate on hydroxyapatite crystallization has also shown an appreciable inhibiting influence of carbonate ion.(5). 

Berner, R. A. The role of magnesium in the crystal growth of calcite and aragonite from seawater. Geochim. Cosmochim. Acta 39. 489-504 (1975). 

Reddy M.M., Plummer L.N. and Busenberg E. (1981) Crystal growth of calcite from calcium bicarbonate solutions at constant Pc02 and 25°C A test of the calcite dissolution model. Geochim. Cosmochim. Acta 45,1281-1291. 

The use of conductance as a measure of the solution composition is limited unless some other control of the composition is possible. Figure 6 illustrates a schematic of the apparatus used to follow the crystal growth of calcite from calcium bicarbonate solutions under constant composition conditions. In this case, the carbon dioxide concentration is kept constant by the flow of a water-saturated mixture of carbon dioxide and nitrogen gas. The conductance is monitored using an a.c. bridge with the analog signal... 

The growth of calcite crystals to form speleothems is a delicately balanced process depending on the degree of supersaturation of the water and its total concentration of dissolved carbonates. Waters dripping onto speleothems require supersaturations on the order of Sk = +0.5 in order to overcome nucleation barriers (where Sic is the saturation index defined in the textbooks cited above). However, the critical supersaturation for 2-dimensional nucleation and the continued growth of a single ciystal is only slightly... 

Trace concentrations of dissolved organic matter and orthophosphates and polyphosphates act as crystal poisons on the nucleation and growth of calcite probably by inhibiting the spread of mononuclear steps on the crystal surface by becoming adsorbed on active growth sites such as kinks. 

Gruzensky, P.M., Growth of calcite crystals, J. Phys. Chem. Solids Suppl., 1, 365, 1967. 

Estroff LA, Addadi L, Weiner S, Hamilton AD (2004) An organic hydrogel as a matrix for the growth of calcite crystals. Org Biomol Chem 2 137-141... 

An important application of soluble oligopolyphosphates is in the threshold treatment of hard water to prevent blockages of pipes arising from the growth of calcite crystals. About one part per million, when added to hard water, will inhibit the precipitation of calcite. This is believed to be due to the absorption of phosphate anions on to the surface of the calcite nuclei, which then prevents further crystal growth. The flexibility and dimensions of the polyphosphate chain allow a good fit to be made on the pattern of ions on the exposed calcite face (12.31) [3]. ... 

The crystalline product obtained with sodium acrylate without addition of the radical initiator was calcite. The mono-carboxylic acid did not exert any influence on the nucleation and crystal growth of CaCOs. The crystal phase of CaCOa obtained without any additives was also calcite. Sodium acrylate was regarded as an inactive form for induction of metastable CaCOs crystalline phases (vaterite or aragonite). 

Poly(N-vinylpyrrohdone) (PVP) is a water-soluble and imcharged polymer. The presence of PVP has no influence on the polymorphs of CaCOs precipitation, but has a morphological effect on vaterite and calcite at high PVP concentration [101]. The precipitate obtained in the initial presence of P VA was calcite (run 2 of Table 3). The crystalline products obtained with N-vinylpyrrolidone without addition of the radical initiator were calcite with a trace amount of aragonite (run 1 of Table 3). These results indicate that both the polymer and monomer did not exert any influence on the nucleation and crystal growth of CaCOs. On the contrary, in-situ polymerization of the monomer during the precipitation of CaCOs was carried out by the doublejet method (Keiun et al, 2006, personal communication). After addition of the calcium reactants into the aqueous solution of the monomer was completed, an aqueous solution of KPS as a water-soluble radical initiator was added to the reaction mixture after incubation at 30 °C for several minutes (1, 3, or 20 min). All the products obtained by the in-situ polymerization were pre-... 

Schindler M, Putnis A (2004) Crystal growth of schoepite on the (104) surface of calcite. Can Mineral 42 1667-1681... 

Spanos, N. and Koutsoukos, P.G., 1998. The transformation of vaterite to calcite effect of the conditions of the solutions in contact with the mineral phase. Journal of Crystal Growth, 191, 783-790. 

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