Study And Application Of Magnetic Composite Material’s Adsorption Behavior To Trace Copper、 Nickel And Cadmium

Based on numerous domestic and foreign references, in consideration of thenano-Fe3O4has high surface energy and large surface area, it can be a goodadsorption of copper, nickel, cadmium and other heavy metal ions, we preparednano-Fe3O4by chemical co-precipitation method and then utilized surfacemodification to prepare magnetic Fe3O4-SiO2microspheres, magnetic Fe3O4thiourea-chitosan and magnetic Fe3O4-SiO2thiourea-chitosan. The three compositematerials were used as the adsorption materials and the flame atomic absorptionspectrometry was adopted as the detection methods to build a new method for rapidand sensitive determination, separation and pre-concentration of heavy metals such ascopper, nickel, cadmium. The main contents of this paper were described as follows:1. This paper briefly describes the significance and progress of heavy metalsanalysis, introduces the determination, separation and pre-concentration methods ofheavy metals and adsorption materials. It mainly focuses on introducing theapplication of magnetic composite materials in separation and pre-concentration oftrace heavy metals, presenting a new method of separation and pre-concentration ofheavy metals by magnetic composite materials and determination of heavy metals byFAAS.2. Magnetic Fe3O4-SiO2microsphere was synthesized by adding TEOS to modifynano Fe3O4. Then the characterization of the synthesized material was performed bySEM, IR and magnetic characterization. The adsorption behavior of magneticFe3O4-SiO2microspheres on trace copper ions was studied under static conditions.The static adsorption capacity was17.95mg/g, with detection limit3.55ng/mL (3σ, n=11), and the relative standard deviation was0.8%. The copper in medicinal herbswas determined by this method and shows satisfactory result.3. The magnetic Fe3O4-thiourea-chitosan was synthesized by modifying thenano-Fe3O4with thiourea-chitosan and then characterized by SEM, IR and magneticcharacterization. With magnetic Fe3O4thiourea-chitosan as the stationary phasematerial separation column, the optimal experimental conditions to separate andpreconcentrate Ni2+was investigated under dynamic conditions. The dynamicadsorption capacity was5.85mg/g, with detection limit0.29ng/mL (3σ, n=11), andthe relative standard deviation (RSD) was0.8%. The trace Ni2+in environmental water samples has been determined successfully with this method, and the recoveriesranged from99.3%to108.3%.4. Magnetic Fe3O4-SiO2thiourea-chitosan was synthesized by modifying themagnetic Fe3O4-SiO2microspheres with thiourea-chitosan and then characterized bySEM, IR and magnetic characterization. With magnetic Fe3O4-SiO2thiourea-chitosanas the stationary phase material micro-column, the optimal experimental conditions toadsorb Cd2+was confirmed by coupling the online micro-column flow injectionpre-concentration with flame atomic absorption spectrometry. At pH7.0, flowing rateof3.9mL/min, sampling time120s, the0.5mol/L HNO3-0.1mol/L Thiourea wasused as eluent for micro-column elution with elution rate of3.6mL/min. Thedetection limit2.5ng/mL (3σ, n=11), and the relative standard deviation (RSD) was0.79%. A result is satisfied when testing the trace cadmium in rice.