Charge transport and heavy metal removal efficacy of graphitic carbon nitride doped with CeO2

Abstract

Doping of graphitic carbon nitride (g-C₃N₄) with semiconductors prevents electron–hole recombination and enhances adsorption capacity. This work investigates the synthesis of a water remediation material using g-C₃N₄ doped with CeO₂ using two different techniques. The chemical structures of the doped g-C₃N₄ samples were confirmed using FTIR, XRD, XPS and their morphology was studied using SEM-EDX. Charge transport through the doped materials was illustrated by a comprehensive dielectric study using broadband spectroscopy. The ability of doped g-C₃N₄ to adsorb heavy metals was investigated thoroughly in the light of applying different parameters such as temperature, pH, time, and concentration. The results showed that the mode of doping of g-C₃N₄ by CeO₂ strongly affected its adsorption capacity. However, g-C₃N₄ doped with CeO₂ using the first mode adsorbed 998.4 mg g⁻¹ in case of Pb²⁺ and 448 for Cd²⁺. Kinetic study revealed that the adsorption process obeyed PSORE as its q^exp_e is close to its q^cal_e and the rate-controlling step involved coordination among the synthetic materials and the heavy metal ions. The recovery of Pb²⁺ and Cd²⁺ ions from various sorbents was investigated by utilizing different molar concentrations of HNO₃ and indicated no significant change in the sorption capability after three different runs. This study has demonstrated an efficient method to obtain a highly efficient adsorbent for removing heavy metals from waste water.