The Preparation And Chelating Properties Of Fe₃O₄/Chelator Composites

It’s well known that magnetic nanoparticles have the macroscopic quantum tunneling effect, small size effect, surface and interface effects, and special magnetic property. So they have novel performances in the mechanical, thermal, electrical, magnetic, optical, and chemical areas. Nowadays the investigation and application of the magnetic nanoparticles have attracted great attentions. Using the magnetic nanoparticles as the core structure, composite nanoparticles with various structural properties can be prepared and can be used in a wide area. This thesis tried to prepare Fe3O4/chelator composites and investigated their application in removing heavy metal in polluted wastewater.A simple co-precipitation method was used to prepare Fe3O4magnetic nanoparticles. The effects of various factors such as concentration, reaction temperature, and the mole ratio of Fe3+and Fe2+ions on the nucleation growth and magnetic properties of the Fe3O4nanoparticles have been investigated.The optimum experimental parameters were obtained by using orthogonal experimental design method. The as-prepared Fe3O4magnetic nanoparticles have a complete granular crystalline with inverse spinel structure. The size of particles is about10nm with a uniform distribution. The magnetization is42.7emu/g with super-paramagnetic, so it can be used as a magnetic recyclable materials. The using of PEG-2000to modify magnetic nanoparticles improved dispersibility.Furthermore, a SiO2layer was coated on the surface of Fe3O4magnetic nanoparticles by the hydrolysis and polycondensation reactions of tetraethoxysilane. The results show that the composite particle surface is still rich of hydroxyl groups, which can further be modificated by amino groups to synthesize Fe3O4@SiO2@NH2. Under the condensation reaction of amino and carboxyl groups, chelating agents of EDTA2Na were combined on the particle surface. The obtained Fe3O4/chelator composites still possess good super-paramagnetic properties with a saturation magnetization of about10emu/g which suggest that these composites can be quickly magnetic recovered.The chelation and chelating efficiencies of Fe3O4/chelator composites on Cr2+, Cu2+, and Ni2+ions were investigated. The results show that the Fe3O4/chelator composites have high chelating efficiencies on Cr2+and Cu+, Ni2+and the metal ions can be effectively removed from the aqueous solutions in a short reaction time, and the chelating composites can also be effective recycling.