Preparation Of Fe₃O₄/4A Zeolite And Adsorption Properties Of Pb（Ⅱ）

Zeolite molecular seives are hydrated aluminosilicate compounds of a porous structure with valuable physicochemical properties. Zeolites have been widely used in ion exchange, adsorption separation and catalysis. Nevertheless, Synthetic zeolite molecular sieves in the current studies are pulverescent. The separation of the particles from a complex heterogeneous system for recycling remains a major obstacle in industrial application. Magnetic separation technology provides a good idea to solve this problem. With this technology, zeolite molecular seives with magnetic property can be effectively separated from the medium by a simple magnetic for regeneration.Magnetic zeolite was successfully synthesized by adding iron oxide into the reaction compounds of zeolite4A through hydrothermal method. The structures and properties of the samples were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM). The adsorption properties of Pb(II) were characterized by Atomic Absorption Spectrophotometry (AAS).In our research, we systematically studied the synthesis of zeolite4A by modifying the synthesis parameters, crystallization time and crystallization temperature. The findings revealed that the optimum conditions for synthesis of zeolite4A were Na2O/SiO2molar ratios=2.5, SiO2/Al2O3molar ratios=1.0, at90℃with6h crystallization time. On this basis, magnetic zeolite molecular sieve were synthesized.The results showed that the introduction of iron oxide particles did not destroy the structure of zeolite4A, but affected its crystallinity, the size of the magnetic composite particles decreased and the morphology of some particles changed with the increasing amount of iron oxide. The highest saturation magnetization was10.0emu/g.Lead ion adsorption experiments indicated that the magnetic zeolite4A possessed well adsorption properties. The adsorption model was consistent with the Langmuir model and the adsorption properties depended on the adsorption conditions.When the initial concentration of Pb is200mg/L and pH=5.0,the optimal amount of the adsorbent was2.0g/L at T=30℃with adsorbing120min, the removal efficiency was92.1%.