Interfacial mechanisms of uranium removal using bismuth hydroxide-impregnated graphitic carbon nitride

Abstract

The effective extraction and recovery of U(VI) from wastewater through a straightforward adsorption approach is essential for mitigating environmental hazards and enabling the recycling of nuclear materials. In this study, a bismuth hydroxide (Bi(OH)3)-doped graphitic carbon nitride (GCN) composite was synthesized and tested for U(VI) adsorption. The GCN/Bi(OH)3 composite was thoroughly characterized using advanced spectroscopy and microscopy techniques including XRD, FTIR, SEM, EDS, and XPS. The influence factors such as pH, initial concentration, contact time, and thermodynamic properties on the adsorption process was thoroughly examined. The maximum U(VI) up taking capacity of GCN/Bi(OH)3 reached 118.56 mg/g at a pH of 4.0 and a temperature of 293 K. This significant enhancement in adsorption capacity demonstrates the effectiveness of Bi(OH)3 doping in improving the material's ability to capture U(VI) ions. The GCN/Bi(OH)3 composite also exhibited a stable spherical structure, excellent regeneration potential, and reusability, making it an ideal candidate for sustainable use. The primary mechanism driving U(VI) adsorption was found to be inner surface complexation through endothermic, as confirmed by experimental and characterization analyses. This study introduces a simple and effective synthesis method for producing GCN/Bi(OH)3, a promising adsorbent for the efficient removal and recovery of U(VI) from radioactive wastewater and re-used more than six cycles with 70% removal efficiency, contributing to environmental protection and resource recovery. © 2025 Elsevier B.V.