Novel magnetic graphene oxide decorated with persimmon tannins for efficient adsorption of malachite green from aqueous solutions

Dyeing effluent is one of the main sources of textile wastewater, which has a seriously destructive impact on human health. A simple and effective way to remove dyes from the environment is required. In this paper, a new adsorbent, magnetic graphene oxide decorated with persimmon tannins (Fe3O4/PT/GO) composites, has been prepared by one-step hydrothermal method for efficient adsorption of malachite green (MG) from aqueous solutions. The microstructure and composition of the Fe3O4/PT/GO adsorbent were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM). The Fe3O4/PT/GO adsorbent had excellent adsorption ability with the maximum adsorption capacity of 560.58 mg/g at 308 K and pH 6.0. The adsorption capacity maintained 85.9% after five cycles. The adsorption process of MG conformed to the Langmuir isotherm model and pseudo-second order kinetic equations. In addition, the thermodynamic studies indicated that the adsorption process is spontaneous and endothermic. All the experimental results showed that the Fe3O4/PT/GO adsorbent had good adsorption capacity for removing MG from wastewater and can be quickly extracted from water under an external magnetic field.