Study On The Controllable Synthesis And Adsorption Properties Of Magnetic Core-shell Structure Microspheres

The rapid industrialization has generated contamination and intensified the invasion of contamination into water.Accumulated industrial pollution greatly do harm to human health and environment even at a quite low concentration.Among all the methods,adsorption technology is considered to be the better effective method,magnetic microspheres?Fe₃O₄?and their complexes are widely used as adsorbent.However,magnetic microspheres are more easy to rust corrosion in the wastewater,especially they have a large tendency to aggregate driven by high interface energy and vander Waals forces because of their ultrasmall nanoparticle size.Therefore,a simple synthesis of core-shell structured microspheres which combine the functionalities of the magnetic microspheres and shell,is desirable from the viewpoint of applications,aiming to remove pollutants from the wastewater.In this work,two kinds of core-shell structured microspheres are prepared.one is magnetic core-shell structured microspheres with a carbide shell,the other is magnetic core-shell structured mesoporous silica microspheres with accessible carboxyl functionalized surfaces and radial oriented large mesopores.Then the properties of two kinds of core-shell structured microspheres are investigated in detail.This work includes the following two main parts.The first part:by solvothermal method,sol-gel method and the high temperature carbonization,this work has successfully developed a controllable method to generate core-shell structured microspheres which possess an internal magnetic microsphere?Fe₃O₄?with a multifunctional carbide shell.The well-designed core-shell structured microsphere was thoroughly characterized by transmission electron microscopy,raman spectroscopy,scanning electron microscopy,x-ray diffraction as well as magnetization measurement.The thickness of resorcinol formaldehyde resin as intermediate transition shell could be easily adjusted by changing the concentration of chemical reagent.The synthetic core-shell structured microspheres possess uniform size?380 nm?,high magnetization(24.81 emu g^-1)and well-defined structure.The novel microsphere of the magnetic core-shell structured microspheres exhibited extraordinary good adsorption capacity,adsorption rate and higher removal efficiency for contamination from the wastewater and quickly magnetic separation in the wastewater treatment application.The second part:this work report the fabrication of a unique core-shell structured microsphere which is composed of ordered mesoporous silica shell with accessible carboxyl functionalized surfaces and nonporous silica-coated magnetite core?Fe₃O₄?,and radial oriented large mesopores,aiming to remove heavy metal ions from wastewater.The well-designed core-shell structured microspheres were thoroughly characterized by scanning electron microscopy,transmission electron microscopy,infrared spectroscopy,x-ray diffraction,N₂ adsorption-desorption as well as magnetization measurement.The as-prepared core-shell structured microspheres possess unique properties including accessible carboxyl groups stably and grafted,highly open mesopores?11.3 nm?,large BET surface area(165 m²g^-1),and high magnetization(34.5 emu g^-1),and as a result,the as-prepared core-shell structured microspheres exhibit enhanced performance for removing Cd?II?,Cu?II?,and Pb?II?from wastewater,with a rapid adsorption rate,a high adsorption capacity,an easy magnetically separable process.