Synthesis and Characterization of Monetite from Calcium Carbonate Recovered from Carpet Waste

Abstract

Calcium carbonate (CaCO3) was recovered from the carpet waste by combustion at 500 °C under an air atmosphere. The CaCO3 had a pure calcite phase without detection of other crystalline phases, as confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements. Dicalcium phosphate (CaHPO4) or monetite, which is known as a family of calcium phosphate-based biomaterials, was synthesized by mixing the CaCO3 recovered from the carpet waste with phosphoric acid (H3PO4) solution. The reaction was kept at a constant temperature of 80 °C for 24 h. The XRD and FTIR results demonstrated that the pure monetite phase was successfully formed by the reaction between CaCO3 and H3PO4. The energy-dispersive X-ray spectroscopy analysis confirmed that the monetite was composed of calcium, oxygen, and phosphorus. The results obtained in this work revealed that CaCO3 recovered from carpet waste could potentially be an alternative material for the synthesis of monetite under mild conditions.