Facile assembly of three-dimensional cylindrical egg white embedded graphene oxide composite with good reusability for aqueous adsorption of rare earth elements

A porous three-dimensional (3D) macrostructure was facilely fabricated by embedding egg white (EW) into graphene oxide (GO) (CEG) under hydrothermal condition. The microstructure, pore size distribution and surface compositions of CEG were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The as-prepared 3D CEG composite was used for the aqueous adsorption of rare earth elements (REEs) including La(III), Y(III), Yb(III), Er(III) and Nd(III) from aqueous solutions. The condition parameters such as contact time, initial REEs concentration, pH values and adsorption temperature were investigated. The adsorption could achieve equilibrium within 90 min and the adsorption of REEs onto 3D CEG(1:1) composite fitted well to the pseudo second-order kinetics model and the Langmuir isotherm model. Thermodynamic and kinetic studies indicated that the adsorption process was endothermic and spontaneous in nature. The maximum adsorption capacities of 3D CEG(1:1) composite were 42.80, 32.16, 56.44, 51.44 and 50.16 mg g(-1) toward La(III), Y(III), Yb(III), Er(III) and Nd(III), respectively. The 3D CEG(1:1) composite was used to remove the La(III), Y(III), Yb(III), Er(III) and Nd(III) from Yudai river water, Xiangjiang river water, spring water and tap water with spiked recoveries in the range 62.6-99.6%. The 3D CEG(1:1) composite showed a good adsorption-desorption ability, and the percentage removal of 3D CEG(1:1) composite for Yb(III) remained constant of 100% at a low Yb(III) concentration even after five cycles.