Effect of pH and temperatures on the fast precipitation vaterite particle size and polymorph stability without additives by steamed ammonia liquid waste

This paper reports on the effect of pH and temperature on size and polymorph stability of calcium carbonate (vaterite) formed without use of additives by Steamed ammonia liquid waste. The effect of the reaction temperature (20-80 degrees C), the initial Steamed ammonia liquid waste pH (1.5-12.1) and the stirring speed (800 and 1200 rpm/min) on the preparation of CaCO3 with respect to the particle size and polymorph stability of final product were investigated. The obtained different CaCO3 size and polymorphs were characterized with Fourier transform infrared spectroscopy (ITIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and a Laser particle size analyzer (LPSA). The phase of vaterite transformed to calcite with increasing temperature 20 to 80 degrees C The SEM and LPSA show that the CaCO3 particle size increased from nano to several micron with the increase of temperature. When the initial CaCl2 aqueous solution in low pH (1.5 and 2.6), nano-micro porous spherical vaterite can be obtained. When the initial CaCl2 aqueous solution in high pH (11.7 and 12.1), preparation of CaCO3 is mainly for the vaterite contains a small amount of calcite and the size particle increased. The possible mechanisms for the porous vaterite CaCO3 formation have also been discussed. Since requirements for the physical properties of CaCO3 particles are diverse for industrial and medical applications, it is important to understand CaCO3 crystallization behavior for tailored particle synthesis. (C) 2020 Elsevier B.V. All rights reserved.