Green Preparation of Precipitated Calcium Carbonate from Limestone Without Calcination Step

Abstract

Limestone collected from Gunung Kidul Regency (Special Region of Yogyakarta, Indonesia) has been used to synthesize precipitated calcium carbonate (PCC) without calcination step. This paper evaluates the effect of calcination of limestone, HNO3 concentration of dissolution, and reaction time of carbonation on the PCC properties. The PCC was synthesized by dissolving the limestone powder in HNO3 solution in various concentrations (0.5 M, 0.7 M, and 1.0 M with) for different times, and followed with carbonation with CO2 flow at various times (30, 45, and 60 minutes) to produce precipitate (CaCCb). The residue was then washed and heated at 105 °C for 8 h to result in PCC and then characterized with FTIR, XRD, and SEM-EDX. Analog work was performed with a limestone calcination step at 900 °C for 5 h before being dissolved in HNO3 solution. The result showed that the highest PCC yield (more than 90%) containing calcite and vaterite was found when the dissolution was used 1.0 M HNO3 and a carbonation time was 30 minutes. Due to low energy consumption, comparable yield and properties, preparation of PCC without limestone calcination step revealed a green and prospective process for the large scale production.