Abstract

Ultrafine calcium carbonate is a widely used cheap additive. The research is conducted in low degree supersaturation solution in order to study the polymorphic phases’ change and its factors of the calcium carbonate precipitate in the ammonification‐carbonization process of the solution with calcium. Fine particles of calcium carbonate are made in the solution containing 0.015 mol/L of Ca2+. Over 98% of the calcium carbonate precipitate without ammonification resembles the morphology of calcite, while the introduction of ammonia can benefit the formation of vaterite. It was inferred that the main cause should be serious partial oversaturation or steric effects. Ammonia also helps to form the twin spherical calcium carbonate. However, particles formed in the process of ammonification‐carbonization in solution with low concentration degree of calcium are not even with a scale of the particle diameter from 5 to 12 μm. Inorganic salts, alcohol, or organic acid salts have significant controlling effect on the particle diameter of calcium carbonate and can help to decrease the particle diameter to about 3 μm. Anionic surfactants can prevent the conglobation of calcium carbonate particles and shrink its diameter to 500 nm–1 μm.

Highlights

  • Ultrafine calcium carbonate of nano- and submicron size is widely used as cheap additive in manufacturing plastic, rubber, varnish, ink, paper, paint, medicine, and other fields [1, 2]

  • Adding ammonia to the solution helps to form the vaterite, and the precipitate of calcium carbonate is the mixture of calcite and vaterite

  • The influence of ammonia on crystal morphology of calcium carbonate precipitate is achieved by creating great partial degree of supersaturation

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Summary

Introduction

Ultrafine calcium carbonate of nano- and submicron size is widely used as cheap additive in manufacturing plastic, rubber, varnish, ink, paper, paint, medicine, and other fields [1, 2]. Mix solution with Ca2+ and solution with CO32− or add organic substance to regulate the mass transfer of Ca2+ and CO32− to control nucleation and formation of crystal. The method of the reaction of Ca(OH) solution and CO2 gas [15] is the major way for industrial ultrafine calcium carbonate making considering the production cost. In this method, Ca(OH) solution can be replaced by other solutions with Ca2+, such as CaCl2 solution. In the system with low degree of supersaturation, the control of the morphology of calcium carbonate particles will be easier. It can Ca2+, such explain how solutions as calcium sulfate, can with form the calcium carbonate materials with unique morphology

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