Abstract

JIMOH, Onimisi A. et al. Understanding the Precipitated Calcium Carbonate (PCC) Production Mechanism and Its Characteristics in the Liquid-Gas System Using Milk of Lime (MOL) Suspension. S.Afr.j.chem. (Online) [online]. 2017, vol.70, pp.01-07. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2017/v70a1.

This study investigates the effect of operating variables and influence of milk of lime (MOL) conditions in PCC using a modified reactor. The variables includes: Ca(OH)₂ feed concentration at 0.5 M-2.0 M and CO₂ flow rates at 224.0 mL min^-1 and 379.5 mL min^-1, on the particle morphology and size in the gas-liquid route precipitation. The particle morphology and texture as well as the chemical content were sufficiently authenticated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray fluorescence (XRF). Experimental data show that lower concentration (<1.0 M) favoured the formation of rhombohedra calcite crystals with the particle size below 100 nm. However, increase in concentration and gas flow rate yielded a coarser crystal particles. Two polymorphs were produced at1Mreactant, i.e. rhombohedra calcite with CO₂ flow rate of 224 mL min^-1 and prismatic calcite at 380 mL min^-1. Molarities higher than 1 M yielded a coarser prismatic crystals, and also has a tendency to crystallize into scalenohedron species especially with higher reactant concentration.

Keywords : Milk of lime; precipitated calcium carbonate; morphology; particle size; carbonation.

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