Fabrication, characterization, and adsorption capacity for cadmium ions of graphene aerogels

In this study, graphene oxide (GO) was prepared from graphite by improved Hummers method. Graphene aerogels (GAs) were synthesized from GO by chemical reduction in which ethylenediamine (EDA) was used as a reducing agent. Influences of conditions on GA synthesis including content of EDA, reduction temperature and time were investigated. The structure and morphology of GAs were studied by density, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) specific surface area. It was found that the suitable conditions of GA synthesis were 30 μL of EDA, reduction temperature of 90 °C, and time of 6 h. The density and BET specific surface area of suitable GA were determined to be 4.57 mg/cm3 and 845 m2/g, respectively. FTIR, XRD, and Raman results showed the oxygen-containing groups on the GO surface were partially reduced and self-assembly of reduced GO formed three-dimensional framework. SEM images presented the interconnected porous structure of GA with the pore size of 50 μm. The suitable GA was used as an adsorbent for removal of cadmium ions (Cd2+) from water. Effects of factors including pH, contact time, and initial Cd2+ concentration on the adsorption capacity of GA were studied. The adsorption data fitted well to a pseudo-second-order kinetic and Langmuir isotherm models with the maximum adsorption capacity of 149.25 mg/g. Accordingly, GA could be used as a potential adsorbent for removal of Cd2+ ions from water.