Study On Modification Of Layered Manganese Dioxide And Its Performance For Adsorption Desulfurization

Layered manganese dioxide is a kind of layered compounds with special properties, it is easy to insert other molecules or ions between the layers, which make it own stronger ion exchange capacity, additionally, the lighter layer board is easy to be exfoliated to get 2D nanosheets. With good chemical properties and excellent structure characteristics, it can be used as electrode materials, applied to chemical sensing technology in electrochemistry. In terms of environmental governance, it can be used as superior adsorbent for heavy metals, toxic waste water and exhaust gas. In the aspect of heterogeneous catalysis, it can be used as precursor of other types of manganese oxides. Therefore, the preparation and use of layered manganese dioxide will remain to be importantly researched in the future.In this prsent research, hydrothermal method was developed to synthesize layered manganese dioxide with superior crystal structure; 2D nanosheets was obtained by swelling method and soft chemical method; Ag+-MnO2 was obtained by ion exchange; by compositing Ag2O and manganese dioxide nanosheets, Ag2O-MnO2 was obtained; by using surfactant and organic solvents, Ag-MnO2 nanosheets (Ag-MnO2NS) was synthesized. All the samples as-prepared were used in adsorption desulfurization reaction. The phase structure, skeleton structure, morphology, and other more properties of the as-prepared materials were characterized by X-ray diffraction (XRD), laser Raman spectroscopy(LRS), scanning electron microscopy(SEM), high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy(HR-TEM-EDX), Brunauer-Emmett-Teller (BET), and Fourier transformation infrared spectrometer (FTIR). Adsorption desulfurization performance was investigated by adsorption of ethyl mercaptan (EM).The results showed that layered manganese dioxide with excellent structure was obtained under the suitable conditions. Specific surface area of nanosheets was about 10 times than that of its parent material, which greatly improve the surface properties. The samples after modifying and compositing can both be stable existing and have good crystal structure. Especially, the Ag-MnO2 NS showed superior interface properties and homogeneous morphology. Ions between layers had the certain affinity function with organic sulfur; the 2D nanosheets enhanced the adsorption ability because of expanding of surface area, which gave sufficient time for adsorbent and adsorbate to contact and react. Ag-MnO2 NS showed the best result because of the strong adsorbablity between nanosheets and ethyl mercaptan and the strong affinity between Ag and organic sulfur. Ag-MnO2 NS showed synergistic effect between Ag and Mn, and improved adsorption capacity in both physical adsorption and chemical adsorption.