▎ 摘　　要

In this work, a layered nanocomposite with a superior adsorption ability has been designed and prepared for the preconcentration of Eu(III), a chemical analogue of trivalent lanthanides [Ln(III)] and actinides [An(III)] in nuclear waste. This nanocomposite was obtained by fabricating magnesium silicate (MgSi) of the Talc-phase Mg3Si4O9(OH)(10) on graphene oxide (GO) nanosheets, in which the GO matrix can effectively avoid the agglomeration of MgSi. A hierarchical structure of GO@MgSi with interwoven nano-sized MgSi lamellae dispersedly standing on the surface of GO was observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Such a hierarchical structure effectively increases the surface area of MgSi, leading to up to date the highest adsorption capacity (344.82 mg.L-1) for enriching Eu(III). Powder X-ray diffraction pattern (PXRD) of Mg3Si4O9(OH)(10) shows that the (0 2 0) and (2 0 0) diffraction peaks disappear after the adsorption of Eu(III), indicating structural changes in MgSi lamellae after adsorption. The infrared absorption spectra (IR) and X-ray photoelectron spectroscopy (XPS) measurements confirm the structural transformations in the Si-O tetrahedral and Mg-OH octahedral sheet in MgSi, suggesting that MgSi lamella rather than GO sheet might play a dominant role during the adsorption process. The superior adsorption behaviors of GO@MgSi indicate that it is a highly promising and efficient candidate for Eu(III) preconcentration in aqueous solution.