A porous molybdenum disulfide and reduced graphene oxide nanocomposite (MoS2-rGO) with high adsorption capacity for fast and preferential adsorption towards Congo red

In this study, a porous nanocomposite of molybdenum disulfide and reduced graphene ( MoS2-rGO) was fabricated through an one-step hydrothermal synthesis. The composition, microstructure and formation of the nanocomposite were carefully characterized by scanning electron microscope, transmission electron microscope, Raman spectroscopy and X-ray diffraction. The results indicate that the three dimensional porous nanocomposite consists of rGO and lamellar MoS2 nanosheets, both of which are evenly distributed. The N-2 adsorption-desorption measurement indicates that the composite material has a mean pore size of 35 nm and possesses specific surface area of 44.4 m(2)/g. The MoS2-rGO nanocomposite displays fast adsorption towards Congo red with maximum adsorption capacity reaching 440.9 mg/g at pH = 3. The adsorption kinetics and the adsorption thermodynamics were studied in detail, and the analyses suggest that the pseudo-first-order model and the Langmuir adsorption isotherm adequately describe the adsorption. The charge sign of the nanocomposite was measured in order to understand the dependence of adsorption capacity on pH. According to the results, the p-p conjugation between the MoS2-rGO nanocomposite and Congo red plays critical role on the adsorption. Moreover, the MoS2-rGO nanocomposite exhibits preferential adsorption towards Congo red in dye-coexisting mixture. Therefore, such a porous MoS2-rGO nanocomposite is considered to have practical application to remove or enrich Congo red. (C) 2017 Elsevier Ltd. All rights reserved.