Preparation Of Functionalized β-CD/Fe₃O₄/GO For Adsorption Of Heavy Metal Ions And Dyes

With the continuous advancement of global industrialization,the pollution of water resources caused by heavy metal ions and dyes has become increasingly serious,which has posed a serious threat to the ecological environment and human health.Therefore,how to effectively remove heavy metal ions and dyes contained in wastewater is of significance study.In this thesis,beta-cyclodextrin/ferroferric oxide/graphene oxide（β-CD/Fe₃O₄/GO）nanocomposite was synthesized using differentin-situcompositetechnology.Andthen,using3-mercaptopropyltrimethoxysilane（3-MPTS）and sodium alginate（SA）as modifying agents,mercapto-functionalizedβ-CD/Fe₃O₄/GO complex（β-CD/Fe₃O₄/GO-SH）and SA functionalizedβ-CD/Fe₃O₄/GO（β-CD/Fe₃O₄/GO@SA）were prepared,respectively,and their adsorption properties for heavy metal ions and dyes were investigated.（1）Theβ-CD/Fe₃O₄/GO nanocomposite was prepared by co-precipitation method,and then,theβ-CD/Fe₃O₄/GO was modified to prepareβ-CD/Fe₃O₄/GO-SH using3-MPTS.The structure,morphology and composition of the samples were characterized by transmission electron microscope（TEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FTIR）,N₂ adsorption/desorption isotherm,X-ray photoelectron spectroscopy（XPS）,thermogravimetric analysis（TGA）and Vibrating Sample Magnetometer（VSM）.The adsorption properties ofβ-CD/Fe₃O₄/GO-SH for Ag（Ι）and MB in a single system were explored,and the effects of solution pH value,initial concentration and contact time on the adsorption properties were investigated.The adsorption kinetic properties of the samples were studied using pseudo-first-order,pseudo-second-order and intra-particle diffusion kinetic models.Langmuir and Freundlich isothermal adsorption models were employed to evaluate the isothermal adsorption process of the samples.The results showed that theβ-CD/Fe₃O₄/GO-SH with superparamagnetism has been successfully prepared,which completely achieved magnetic separation in aqueous solution.The maximum adsorption capacity ofβ-CD/Fe₃O₄/GO-SH for Ag（Ι）and MB reached101.87 mg/g and 105.74 mg/g,respectively.The results of XPS analysis co nfirmed that the mercapto groups on the surface ofβ-CD/Fe₃O₄/GO-SH had excellent affinity for Ag（I）,and Ag（Ι）was reduced to Ag elemental during the adsorption process.The adsorption process ofβ-CD/Fe₃O₄/GO-SH for Ag（Ι）and MB conformed to the pseudo-second-order kinetic model,which revealed that the adsorption process was mainly chemical adsorption.The isotherm adsorption process ofβ-CD/Fe₃O₄/GO-SH for Ag（Ι）was in accordance with the Freundlich isotherm model,indicating that the adsorption of Ag（Ι）on the surface ofβ-CD/Fe₃O₄/GO-SH was uneven multilayer adsorption,while Langmuir isotherm model could better describe the isotherm adsorption process of MB byβ-CD/Fe₃O₄/GO-SH,which illustrated that the adsorption of MB on the surface ofβ-CD/Fe₃O₄/GO-SH was even monolayer adsorption,（2）Theβ-CD/Fe₃O₄/GO nanocomposite was synthesized by solvothermal method,and thenβ-CD/Fe₃O₄/GO was dispersed into SA matrix to successfully prepare theβ-CD/Fe₃O₄/GO@SA by phase transfer method and freeze-drying technique.The structure,morphology and composition of the samples were characterized by scanning electron microscope（SEM）,FTIR,N₂ adsorption/desorption isotherm and XPS.The adsorption properties ofβ-CD/Fe₃O₄/GO@SA for Pb（ΙΙ）and MB were studied,and the effects of solution pH,initial solution concentration and time on adsorption properties were investigated.The pseudo-first-order and pseudo-second-order kinetic models and the intra-particle diffusion model were used to evaluate the adsorption kinetics process of the samples on Pb（II）and MB.The isothermal adsorption process of samples were studied by Langmuir and Freundlich isothermal adsorption model.The results proved that theβ-CD/Fe₃O₄/GO@SA with magnetic responsiveness and three-dimensional network structure was successfully prepared.The maximum adsorption capacity ofβ-CD/Fe₃O₄/GO@SA for Pb（ΙΙ）and MB reached 415.02 mg/g and 657.20 mg/g,respectively.The adsorption process ofβ-CD/Fe₃O₄/GO@SA for Pb（ΙΙ）and MB conformed to the pseudo-second-order kinetic model and Freundlich isothermal model,indicating the adsorption mechanism ofβ-CD/Fe₃O₄/GO@SA for Pb（ΙΙ）and MB was mainly considered to be chemical adsorption,and the adsorption process was a multilayer adsorption that occurred on uniform surface.