Preparation and characterization of calcite/biochar composites fabricated by co-pyrolysis technique

In this study, calcite/biochar (CAL/BC) porous composites were synthesized via the co-pyrolysis of coconut shell (CS) and calcite (CAL) at temperatures ranging from 500°C, 600°C and 700°C. The surface morphology, chemical composition, and electrochemical properties of the CAL/BC composites were characterized using scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), BET analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and electrochemical workstation. The results revealed that CAL/BC composites produced at 700°C exhibited the highest adsorption capacity for Pb solution among all synthesized materials, with a maximum adsorption capacity of 79.8 mg/g. Furthermore, excellent regeneration properties were observed for all CAL/BC composites prepared at 500°C, 600°C, and 700°C, with a high removal rate of Pb maintained after four adsorption-desorption cycles. The CAL/BC composite synthesized at 700°C exhibited the lowest corrosion current density of 6.314×10-6 A/cm2, indicating the most outstanding corrosion resistance among all three CAL/BC composites. Conversely, the highest corrosion current density of 8.871×10-5 A/cm2 was observed in the CAL/BC composite prepared at 500°C, indicating the most inadequate corrosion resistance of this composite.