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.