Fabrication of novel 4-methyl-5-thiazoleethanol covalently-linked graphene oxide composite with adsorption selectivity for Cu2+ from aqueous solutions

Abstract

BackgroundThe covalent coupling of specific organic components to graphene oxide (GO) can improve its adsorption selectivity and reduce its hydrophilicity for fast separation by acylation of the abundant carboxyl groups (-COOH) on the surface. MethodsIn this study, a novel composite material with excellent adsorption selectivity toward copper ions (Cu2+) was prepared by covalent-linking of 4-methyl-5-thiazoleethanol (MTE) to GO through a facile one-step esterification reaction. The composition and morphology of GO-MTE composites pre- and after-adsorption of Cu2+were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses. The adsorption conditions of GO-MTE composite for Cu2+were investigated and optimized. To further reveal the possible adsorption mechanism of GO-MTE composite toward Cu2+, the experimental data were fitted by different adsorption dynamics and isothermal models. The reusability of GO-MTE composite was evaluated by repeating the adsorption/desorption experiments in eight consecutive cycles. Significant findingsThe introduction of MTE effectively inactivates most of the carboxyl groups of GO, and the covalently-linked thiazole ring with N- and S-containing heteroatoms endows GO-MTE composite with excellent adsorption selectivity for Cu2+ in aqueous solution. The adsorption capacities of GO-MTE composite for Cu2+ are 2.39, 17.08 and 26.64 times higher than those of Pb2+, Nd3+ and Y3+, respectively, indicating that it possesses stronger binding ability for Cu2+. After eight adsorption/desorption cycles, the recycled GO-MTE composite still maintained high adsorption capacity and removal rate for Cu2+, indicating that GO-MTE composite possesses excellent stability and reusability, and it could be used for the separation and recovery of Cu2+ from aqueous solutions.