Abstract
Porous rGO/SiO2 nanocomposites with a “core-shell” structure were prepared as an efficient adsorbent for the liquid-phase adsorption of cationic neutral red (NR) dye. The samples were characterized with powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 and water vapor adsorption/desorption methods. The NR removal ability and kinetics of the adsorption process of SiO2 and the rGO/SiO2 nanocomposites were investigated at 298 K. The rGO/SiO2 nanocomposite SG 0.30 showed a superior adsorption of NR dye. In regard to NR at pH 5, we measured a superior adsorption capacity of 66.635 mg/g at an initial NR concentration of 50 mg/L. The experimental adsorption capacity of SG 0.30 was 3.791 times higher than that of SiO2. Then, we compared the results with similar materials used for NR removal. Moreover, the water adsorption sites provided by the nitrogen- and oxygen-containing groups might be one of the reasons for the increased adsorption of water vapor. The broad range of properties of the rGO/SiO2 nanocomposite, including its simple synthesis, ability to be mass prepared, and strong adsorption properties, makes it a truly novel adsorbent that can be industrially produced, and shows potential application in the treatment of wastewater-containing dyes.
Highlights
With the development of modern industry, water pollution is one of the primary environmental issues in China because it can be harmful to human health and can affect people’s lives [1,2].Adsorption is an effective method of solving water pollution
The morphologies and nanostructures of the SiO2 and rGO/SiO2 nanocomposites were examined via field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM)
A similar structure was observed in the SEM image in Figure 1c, where SiO2 was wrapped in graphene powder with a rough surface
Summary
Adsorption is an effective method of solving water pollution. Various materials, such as activated carbon [3,4], zeolites [5,6], metal oxides [7], and organic–inorganic hybrids [8], have been used as adsorbents. Adsorption with activated carbon is highly developed, the cost of reprocessing and regeneration is high. The microporous structure of zeolites limits their application in the field of dye adsorption. Metal materials are costly and do not have good enough adsorption capacity. These limitations encourage the search for inexpensive and readily available materials as adsorbents for the removal of dyes
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