Scavenging mechanism of rare earth metal ions in water by graphene oxide

In order to investigate scavenging mechanism of rare earth metal ions in water by graphene oxide (GO), effects of ion concentration and adsorption time on the adsorption of the metal ions, such as La(III) and Nd(II), were surveyed systematically. The molecular structure, surface functional groups and morphology of the GO before and after adsorbing the rare earth metal ions were characterized by Raman spectroscopy, FITR, and XPS. To shed more light on the sorption mechanism, static density functional theory (DFT) calculation was introduced to portray the molecular-scale interaction between GO and the rare earth metal ions. The results indicated that the GO showed high adsorbing capacities of 105.5 mg/g for La( III) and 99.1 mg/g for Nd(II) at 20 degrees C and pH 5.5, respectively. The adsorption reached equilibriums within 120 min and the adsorption kinetics of La(III) and Nd(II) followed the pseudo-first-order kinetic model well. The Freundlich and Langmuir models were used to simulate the adsorption isotherms of the rare earth metal ions, demonstrating that the adsorption fitted well with Langmuir model. Experimental results of this work demonstrated that GO was a promising economical material for the removal of La(III) and Nd(II) from aqueous solutions. (C) 2020 Elsevier B.V. All rights reserved.