Surface Modification of Precipitated Calcium Carbonate(PCC)-Derived From Indonesia’s Limestone using Sodium Tripolyphosphate and Sodium Stearic

Limestone is an abundant natural resource in Indonesia that can be utilized to synthesize PCC (precipitated calcium carbonate). This study aimed to modify the PCC surface using Sodium Tripolyphosphate (NaTPP) and Sodium Stearic (Sodium stearic) as the modifier. PCC was successfully synthesized using the caustic soda method. Firstly, limestone was calcined at 900°C, the solid powder was immersed into 6M of HNO₃, and 1 M of Na₂ CO₃ was added to the mixture. The PCC in this study was modified with Sodium Tripolyphosphate and Sodium Stearic; then, the solid powders were characterized by XRD, FTIR, and Water Contact Angle (WCA). Based on the results of the AAS characterization, limestone contains 45.87% of calcium carbonate, and PCC-NaTPP contains 80% of calcium carbonate. Characterization using contact angle resulted in a contact angle of 128° at PCC-NaTPP with the addition of 4% Sodium stearic and a reaction temperature of 60°C. Characterization using FTIR marked the phosphate functional group from the addition of NaTPP and the C=O functional group caused by fatty acids from sodium stearic. XRD pattern of PCC represents the successful transformation from the dolomite phase to calcite, which refers to the CaCO₃ structure. Then, the higher contact angle obtained with sodium stearic modification leads to the lower surface free energy.