Graphene oxide-modified organic Gaomiaozi bentonite for Yb(III) adsorption from aqueous solutions

Abstract

Bentonite, known as all-purpose soil, is a kind of clay widely used in engineering. Graphene oxide (GO) has a broad application prospect in many fields as a superior adsorbent. In this study, a new type of adsorbent, graphene oxide modified organic Gaomiaozi (GMZ) bentonite was synthesized. The adsorption behavior of Yb(III) through batch experiments on the GMZ bentonite and graphene oxide-modified organic GMZ (GO-GMZ) bentonite was studied. Before the experiments, the two adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results show that the adsorption of Yb(III) onto GMZ bentonite and GO-GMZ bentonite reaches equilibrium within 60 min. The Yb(III) adsorption process is well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum Langmuir adsorption capacity of Yb (III) onto GO-GMZ bentonite is 36.90 mg/g higher than that onto GMZ bentonite of 34.48 mg/g, which demonstrates that the GO-GMZ bentonite improves the adsorption performance of GMZ bentonite. It can also be confirmed by the characterization results that the montmorillonite layers in GO-GMZ bentonite have a larger pore structure and layer spacing, which is beneficial to the intercalation of cations. Because the GO-GMZ bentonite has the main composition of bentonite, it can help to eliminate the irreversible aggregation and accumulation of graphene oxide in solutions and can improve the recyclability of bentonite. Considering the other advantages of bentonite such as low-cost, high stability, easy availability, and environmental friendliness, it is worth popularizing and applying the new GO-bentonite adsorbent.