Highly crystalline lithium chloride-intercalated graphitic carbon nitride hollow nanotubes for effective lead removal

Abstract

The functional groups and intercalated ions in the structure of graphitic carbon nitrides can be tailored to attain excellent physiochemical properties for environmental remediation. In this work, a highly crystallized lithium chloride-intercalated graphitic carbon nitride (LiCl-CN) material was fabricated through well-controlled molten salt synthesis. The as-prepared materials presented hollow tube morphology with tetragonal geometric configurations. Batch adsorption experiments showed that the LiCl-intercalated graphitic carbon nitride (LiCl-CN-4 h) exhibited excellent lead cation (Pb(II)) adsorption capacity (172.41 mg g⁻¹) at pH 5.5. Thermodynamic parameters revealed the endothermic and spontaneous nature of Pb(II) adsorption on LiCl-CN-4 h, and the kinetics results demonstrated that chemisorption dominated the adsorption process. X-ray diffraction analysis indicated that the intercalation of Cl and Li can lead to a larger interlayer spacing between carbon nitride layers. An X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigation further elucidated the chemical binding sites of Cl–Pb in the lattice of LiCl-CN, indicating the intercalation of Cl⁻ ions contributed to the large improvement of Pb(II) adsorption capacity in g-C₃N₄ materials. The experimental results demonstrate that this is a facile and environmentally friendly strategy for synthesizing highly crystalline LiCl-CN with hollow tube morphology, and that the material showed promise for efficient Pb(II) removal in environmental remediation applications.