engleski

Precipitation of Calcium Carbonate from Calcium Hydroxide and Carbonic Acid Solutions

The influence of initial reactant concentrations (c(Ca(OH)2) = 2.0ˇ10-3 – 1.0ˇ10-2 mol dm-3 and c(H2CO3) = 1.0ˇ10-3 – 1.2ˇ10-2 mol dm-3) on the composition, morphology and amount of the precipitates formed by spontaneous precipitation of calcium carbonate at 25 °C has been investigated. Precipitation of calcium carbonate was achieved by mixing equal volumes of both calcium hydroxide and carbonic acid solutions. Propagation of the reaction was followed by measuring pH of the solution in the systems continuously stirred at a constant rate. Precipitates aged for 20 min were characterized by means of a combination of optical microscopy, FT-IR spectroscopy, crystal size distribution and specific surface area measurements. The effect of initial supersaturation is discussed.

Calcium carbonate; Calcite; Vaterite; Precipitation

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