Study On Adsorption Of Cr（Ⅵ） In Metallurgical Wastewater By Amino Functionalized Magnetic Fe₃O₄ Nanoparticles Adsorbent

Metallurgical industry wastewater contains a lot of heavy metal ions,while heavy metal pollution has become a serious environmental and sanitary problem.The un-degradability,traceability,enrichment and other characteristics of heavy metals,which bring serious harm to the environment.After heavy metals are accumulated in human body via the food chain,it will influence severely on human beings and even life-threatening.Functionalized magnetic nanomaterials have extensive application prospects for the characteristics of large specific surface area,controlled magnetic separation,cheap,easy obtained and desirable biocompatibility.This kind of material can be used widely in heavy metal detection and separation on environmental management,protein and DNA separation,targeting medicine,and electrochemical catalysis.In this paper,magnetic Fe₃O₄ nanoparticles were synthesized by chemical precipitation method.Magnetic Fe₃O₄ nanoparticles were coated with SiO)2 on the surface through hydrolysis reaction by using tetraethyl orthosilicate（TEOS）using as silicon source.Then,via 3-aminopropyltris ethoxysilane dehydration conducted condensation reaction,and Fe₃O₄ particles（NH2-Fe₃O₄@SiO）2)riched in-NH2 functional groups were prepared,The as received products were characterized by SEM,XRD,VSM and FTIR.The results indicate that the average particle size distribution of NH2-Fe₃O₄ @ SiO)2 is about 180 200 nm,which is spherical and has a good magnetic response.The amount of TEOS has a significant effect on the morphology of NH2-Fe₃O₄ @ SiO)2.The optimum condition-prepared NH2-Fe₃O₄@SiO)2 were employed in Cr（Ⅵ）adsorption experiment.The experimental results indicate that pH value and initial concentration of Cr（Ⅵ）have a significant influence on the adsorption,and the adsorption process can reach an equilibrium within 50 mins.When system pH = 2,adsorption temperature is 308 K with an acid environment,the adsorbent is exhibited the best adsorption effect,and the saturated adsorption capacity reaches 350.14 mg / g.The Adsorption model of NH2-Fe₃O₄ @ SiO)2 to Cr（Ⅵ）in wastewater is accorded with Langmuir isothermal adsorption model well,and adsorption kinetics is consistented with the quasi-second order rate model.The adsorption thermodynamics data shows that the adsorption process of NH2-Fe₃O₄ @ SiO)2 on Cr（Ⅵ）is spontaneous endothermic process,and the increased temperature is favorable for the adsorption process.In addition,NH2-Fe₃O₄ @ SiO)2 is eluted after adsorption completed,recycling 5 times,the Cr（Ⅵ）adsorption efficiency is still maintained above 90%.The investigation provides a new method for removing Cr（Ⅵ）in metallurgical industry wastewater.Compared with the traditional adsorbents,Fe₃O₄ nanoparticles adsorption on Cr（Ⅵ）has a higher adsorption rate,shorter adsorption time.Under the condition of applied magnetic field,adsorbent can be quickly separated with mother liquor,avoiding the occurrence of secondary pollution.NH2-Fe₃O₄ @ SiO)2 is a potential effective adsorbent for removing Cr（Ⅵ）in metallurgical wastewater.