Ni–Mn LDH-decorated 3D Fe-inserted and N-doped carbon framework composites for efficient uranium(vi) removal

Abstract

Extraction of uranium from seawater is of great interest because of its potential applications in the nuclear energy field. In this study, we prepared 3D Fe-inserted and N-doped carbon nanosheet frameworks by a polymer-blowing process, followed by decoration with nickel–manganese layered double hydroxide (Fe-NCNF-LDH). Employing SEM, FTIR, XPS, XRD, TEM, and BET techniques, we confirmed the existence of 3D structured porous materials with advantageous interconnectivity to provide a highly accessible freeway for uranium(VI) ionic diffusion. We investigated the removal of uranium(VI) from an aqueous solution (ppm level) and simulated seawater (ppb level) by the Fe-NCNF-LDH composites. The results showed that the adsorption process fitted well with a pseudo-second-order model and Langmuir isotherm model. Based on XRD and XPS, before and after the adsorption of uranium(VI), we proposed a possible sorption mechanism (anion exchange, chemical reduction, and surface complexation). In addition, the Fe-NCNF-LDH composites show good adsorption properties after five adsorption–desorption cycles, which augur well for potential application in the field of the adsorption of uranium from seawater.