Abstract
•Graphene oxide was synthesized by a modified Hummers’ method.•The Zn(II) removal by adsorption was directly dependent on the pH.•The Zn(II) adsorption process can be explained by pseudo-second-order kinetic model.•Adsorption of Zn(II) fitted well with Langmuir model at different temperatures.•The maximum adsorption capacity of Zn(II) on graphene oxide was up to 245.70mg/g.
In this study, graphene oxide (GO) was synthesized via modified Hummers’ method, and characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS). The adsorption of Zn(II) on GO as a function of pH, adsorbent dosage, foreign ions, contact time, and temperature was investigated using batch technique. Results showed that the suitable pH for Zn(II) removal was about 7.0, and the optimal dosage was 2mg. The adsorption of Zn(II) onto GO increased sharply within 20min and obtained equilibrium gradually. Meanwhile, foreign ion and temperature also affected the adsorption performance of GO. The adsorption process was found to be well described by the pseudo-second-order rate model. Equilibrium studies indicated that the data of Zn(II) adsorption followed the Langmuir model. The maximum adsorption capacity for Zn(II) was up to 246mg/g with a Langmuir adsorption equilibrium constant of 5.7L/g at 20°C. The thermodynamic parameters calculated from temperature-dependent sorption isotherms suggested that Zn(II) sorption on GO was an exothermic and spontaneous process in nature. The possibility of Zn(II) recovery was investigated and the result revealed that the maximum Zn(II) recovery yield was achieved with hydrochloric acid.