The Simple Method of Synthesizing Calcite and Aragonite from Indonesian Limestone

Precipitated CaCO3 (PCC) with calcite and aragonite phases have been successfully synthesized using natural limestone. Synthesis of PCC was carried out by the simple method of carbonation using slurry Ca(OH)2 with a variation of CO2 gas flow rate at room temperature and variation of temperatures at a constant CO2 gas flow rate. The raw material used is a very high purity Madura Island limestone. The PCC product was characterized by X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FT-IR), and Scanning Electron Microscope (SEM). PCC on CO2 gas flow variation produced the same phase, calcite with the characteristic of 2θ = 29.23° (104), rhombohedral cubic morphology, and a wavenumber of 712 cm-1 as displayed from the FTIR spectra. The mixture of aragonite and calcite phase was observed in PCC products with temperature variations of 60 - 90°C. The characteristic aragonite was observed at 2θ = 26.2° with needle-like morphology. The highest fraction of aragonite was at the temperature of 60°C at 71.35%.