Preparation Of Magnetic Fe₃O₄ Composite Particles For MetaI Ions Adsorption

Ferroferric oxide has been used widely due to its excellent physical and chemical stability, biocompatibility and special magnetic energy in magnetic separation, catalyst, magnetic liquid, biomedicine and environmental governance. Coprecipitation method and solvothermal method were used to prepare magnetic ferroferric oxide nanoparticles, and the influence of reaction system, time and temperature on the product structure and performance was studied. Fe3O4 nanoparticles were coated with SiO2 and PMMA by Stober method and suspension polymerization, respectively. After surface modification using amino, adsorption testsof heavy metal ions were carried out. The specific studies are as follows:(1) Coprecipitation method and solvothermal method were used to prepare magnetic ferroferric oxide nanoparticles with high-purity. The nanoparticles were characterized by using XRD, SEM and VSM. Results show that the size of Fe3O4 nanoparticles is small but agglomerate seriously. While, the dispersity of the Fe3O4 nanoparticles prepared by solvothermal method is better, and they have good superparamagnetic performance. So, we chose the Fe3O4 nanoparticles obtained by solvothermal method as the nuclear particles. This method was carried out in an environment without water, hence, the oxidation of Fe3O4 can be avoided and the operation is simple and feasible.(2) Fe3O4 nanoparticles were coated with SiO2 by Stober method. The effect of TEOS was discussed. The nanoparticles were characterized by using XRD, SEM, TEM and FT-IR. Optimum ratio of process was found. Fe3O4@SiO2 composite particles with uniform particle size and good dispersity were prepared.(3) Fe3O4@SiO2 composite particles were coated with PMMA by suspension polymerization, and their surface was modified using amino. The influence of pretreatment using KH-570 was discussed. The particles were characterized by using XRD, SEM, TEM and FT-IR. Results show that surface pretreatment by using KH-570 can make the surface of Fe3O4@SiO2@PMM A particles more regular and smooth.(4) Fe3O4@SiO2@PMMA particles were modified by amination. The particles were characterized by using FT-IR, and it was ensured that amino has been connected on the surface of Fe3O4@SiO2@PMMA particles.(5) Adsorption tests of Cu2+ and Ni2+ on the Fe3O4@SiO2@PMMA particles treaded by amination were examined. The composite particles were directly added into Cu2+ or Ni2+ solution. Ultraviolet-visible spectrophotometer was used to measure the adsorption situation. Results show that when the pH value is 5.5, the absorption capacity of Cu2+ on microspheres after 2.5 h is about 170 mg/g. When the pH value is 7, the absorption capacity of Ni2+ on microspheres after 2 h is about 72 mg/g.