Study On The Preparation And Sorption Properties Of Molybdenum Disulfide/Reduced Graphene Oxide For Pb(?)and U(?)

With the development of society and industry,the environmental pollutants emitted by mankind to the natural environment are also increasing,including heavy metal pollutants and radioactive contaminants that have great harm to human survival and natural environment.These pollutants are spread throughout the atmosphere,soil,water,sediment and plant systems,which is a great threat to the human,animal and plant and the environment.Therefore,how to effectively and properly deal with these pollutants will have a very important practical and scientific significance.In this paper,we have successfully synthesized layered and novel molybdenum disulfide/reduced graphene oxide?MoS₂/rGO?nanocomposites through a simple hydrothermal method.Based on the batch experiment,we firstly used MoS₂/rGO composites as adsorbents to study the effects of different adsorption conditions?such as time,temperature and so on?and evaluate sorption behavior of heavy metal ions?Pb????and radionuclides?U????,hoping to provide some help to the development of new adsorbents and environmental pollution control.This paper has the following five chaptersThe first chapter is the introduction,we first summarize the sources and hazards of heavy metal ions and radionuclides contamination,and briefly introduce the pollution control methods and the related theories of sorption.Then,the information about molybdenum disulfide?MoS₂?and graphene oxide?GO?and their applications in sorption were introduced.And finally the main content and research significance about this paper are described.In the second chapter,the preparation of MoS₂ and MoS₂/rGO composites were introduced.The materials were characterized and analyzed by a series of methods such as transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results showed that MoS₂ and MoS₂/rGO composites have been successfully synthesized.In the third chapter,the as-prepared MoS₂/rGO composites were firstly applied as adsorbents for efficient elimination of Pb???ions.Batch adsorption experiments showed that the adsorption of Pb???on MoS₂/rGO followed pseudo-second-order kinetic model well.The adsorptionofPb???wasintenselypH-dependent,ionic strength-dependent at pH<9.0 and ionic strength-independent at pH>9.0.The presence of HA enhanced Pb???adsorption obviously.The MoS₂/r GO composites exhibited excellent adsorption capacity of 384.16mg·g^-1 at pH=5.0 and T=298.15 K,which was superior to MoS₂(279.93 mg·g^-1)and many other adsorbents.The thermodynamic parameters suggested that the adsorption process of Pb???on MoS₂/rGO composites was spontaneous??G^?<0?and endothermic??H^?>0?.This work highlighted the application of MoS₂/rGO as novel and promising materials in the efficient elimination of Pb???from contaminated water and industrial effluents in environmental pollution management.In the fourth chapter,the as-prepared MoS₂/rGO composites were applied as adsorbents for efficient elimination of U???ions,and studied the effects of time,temperature,p H and ionic strength.The experimental results showed that MoS₂/rGO composites reached equilibrium quickly in2 hours for removal of radionuclide U???.The MoS₂/rGO composites exhibited excellent adsorption capacity of 83.47 mg·g^-1 for U???according to Langmuir model.Adsorption thermodynamics indicated that the adsorption process was a spontaneous exothermic process.In addition,the adsorption of U???was intensely pH-dependent,and ionic strength-independent.The results of the Fourier transform infrared spectroscopy?FT-IR?and X-ray photoelectron spectroscopy?XPS?analyses demonstrated that MoS₂/rGO composites had good adsorption capacity and behaviour due to their oxygen-containing functional groups,which could form strong surface complexes with heavy metal ions?Pb????and radionuclides?U????.In the fifth chapter,the relevant experimental results of this paper were summarized in detail,and the shortcomings of the experiment and the future research direction of heavy metal wastewater or radioactive wastewater were also discussed.