The Preparation Of Magnetic Nanomaterials And Their Applications In Wastewater Treatment

In recent years, with industrialization speeding up, water pollution is more and more serious in our country. Heavy metal ions are unable to degradate, not easy to converte, and easy to reunite, so they can enter human body easily through various ways. Then heavy metal ions will cause great harm to people’s health, even threaten people’s lives. In order to purify wastewater, people are studying sewage treatment technology actively. As a kind of new adsorption material, magnetic nanomaterials have larger specific surface area. What’s more, duing to their magnetic properties, they are easier to be separated and recycled.In this paper, we synthesized a series of Fe-Ni nanoparticles by hydrothermal method under nitrogen atmosphere. Hydrazine hydrate was chosen as reducing agent, sodium citrate was used as complexing agent. The products were confirmed by XRD, VSM, TEM and TG-DTA. Results showed that composition of nickel and iron can control the structure, surface properties, and magnetic of the products. And when the nickel iron started with1:1and1:2, the products are both superparamagnetism granule.In order to improve the stability of the magnetic nanoparticles and adsorption properties, we preparated silicon dioxide composite magnetic materials by sodium silicate carbonic acid decomposing method. Products’morphology and structure were confirmed by different means which provced that the nanoparticles have a layer of silica on their surfaces, moreover the antioxidant capacity of the composite particles is obviously better than the metal particles.Fe3O4@SiO2å'ŒNi2.33Fe are applied to the adsorption of nickel ions, we discussed the influence of different particles, adsorbent dosage, initial concentration, pH and temperature on nickel ions removal efficiency. It is found that Fe3O4@SiO2is better adsorbent than Ni2.33Fe. The equilibratory adsorption quantity of Fe3O4@SiO2increased with the initial concentration increasing and the pH decreasing when under the condition of weak acid. When the tempreture is below45℃, equilibratory adsorption quantity enhances with the rising of temperature. The study suggested that the adsorpting Ni2+processes of Fe3O4@SiO2and Ni2.33Fe conform to Pseudo-second-order model, thermodynamic accord with Freundlich isothermal model, the adsorption process is largely controlled by chemical adsorption. The investigation on the repeatedly use of adsorbent revealed that the adsorbent can be utilized repeatedly, and the removal ability of Ni2+is stable.We also do some primary researches on absording Cr(VI), the research results showed that Ni2.33Fe has better absorption capability than those who have silica shell. When the initial concentration is50mg-L’1, its equilibrium adsorption quantity is8.040mg·g-1.The absorption process conforms to Pseudo-second-order model, thermodynamic accords with Freundlich isothermal model, the adsorption process is largely controlled by chemical adsorption.