A porous multifunctional and magnetic layered graphene oxide/3D mesoporous MOF nanocomposite for rapid adsorption of uranium(VI) from aqueous solutions

Abstract

A novel adsorbent, GO/Fe3O4/OPO3H2/PCN-222, was successfully synthesized via graphene oxide (GO) modification with magnetic particles, phosphorous-containing groups, and a mesoporous Zr-MOF, PCN-222 (PCN stands for Porous Coordination Network), respectively, to give the nominal composite. The last step was through a solvent-assisted ligand incorporation technique. Morphological, structural, and physicochemical properties of the hybrid material was assessed by FT-IR, PXRD, SEM/EDX, BET surface area, VSM, TGA/DSC, UV–vis DRS, and ICP-OES analyses. This solid was then used for dispersive solid phase extraction of uranium ions dissolved in water. Several parameters including pH of solution, extraction and desorption times, amount of adsorbent, and type and concentration of elution solvent were investigated and optimized. The maximum adsorption capacity of adsorbent was found to be 416.7mgg−1 (pH, 6.2; amount of adsorbent, 5.0mg; extraction time, 3.0min) beyond what was achievable with the individual components. In addition, various coordination modes between the multifunctional adsorbent and uranyl ions were investigated by DFT calculations in details, revealing some favorable non-covalent cation–π interaction and strong binding of free-base porphyrin, carboxyl and phosphorous-containing groups to the uranium ions. Under optimized conditions, high determination coefficient (R2=0.9994) was obtained and limit of detection and relative standard deviation were found 0.9μgL−1 and 2.7%, respectively.