Calcite precipitation inhibitors

However, rates of precipitation in soil systems may be quite different from those in solutions because precipitation is catalysed by adsorption of the reacting solutes onto soil surfaces the nature of the solid phases formed may be different and sorption may also alter the effects of inhibitors. There are very few data in the literature on these effects actually measured in soils. Figure 3.15 shows data of Huang (1990) for calcite precipitation in three soils incubated with urea. Precipitation was induced as the pH increased during urea hydrolysis ... 

The transformation of aragonite to calcite can be catalyzed in solutions containing electrolytes which are not inhibitors of calcite precipitation (e.g., NaCl). This observation has been interpreted to be due to increased concentrations of the calcium bicarbonate ion pair (e.g., Bischoff and Fyfe, 1968) in these solutions. Why this species should catalyze the reaction remains unexplained. 

Seawater in the upper regions of the ocean is strongly supersaturated with respect to calcite, aragonite, and ideal dolomite. Why these minerals fail to precipitate directly from it has been a problem of major interest. In experimental studies (e.g., Pytkowicz, 1965, 1973 Berner, 1975), the magnesium ion has been observed to be a strong inhibitor of calcite precipitation and largely responsible for its failure to precipitate... 

At some level of calcite supersaturation, depending on the concentration and reactivity of inhibitors and other kinetic factors, calcite tends to nucleate and precipitate. Herman and Lorah (1987) noted previous field studies in which calcite precipitation did not occur until CO2 outgassing had raised calcite supersaturation levels to 5 or 10 times above equilibrium. In their own work on Falling... 

The major focus of the research project was the optimisation of the corrective treatment measures that are most commonly used for reducing lead in drinking water. In low alkalinity water supplies, plumbosolvency can be greatly reduced by pH elevation up to 10.0 although the additional dosing of a corrosion inhibitor may be necessary in some cases. In high alkalinity waters, pH elevation may cause problems with calcite precipitation and so it has become common practice to rely on the dosing of a corrosion inhibitor. 

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