The Preparation Of Functional Magnetic Nanomaterials And The Study Of Absorption Cr(?)

Because of the industrial continued development,the pollution of heavy metals is increasingly serious.The excessive intake of heavy metals is harmful to human body and affect people's health.Functional magnetic nanomaterials is a new material with highly efficient,non-toxic and recyclable.In the processing of heavy metals which has become a hot spot of research at home and abroad.In this article,Fe3O4 particles were synthesized through chemical precipitation,then surface modification was carried out on the Fe3O4 particles,the Fe3O4@Vc magnetic nanomaterials,Fe3O4@SiO2 magnetic nanomaterials and Fe3O4@SiO2@CS magnetic nanomaterials were prepared.The there functional magnetic nanomaterials were characterized by TEM,FTIR and XRD.In this paper,hexavalent chromium ion in water was selected as the research object,The properties of Fe3O4@Vc magnetic nanomaterials,Fe3O4@SiO2 magnetic nanomaterials and Fe3O4@SiO2@CS magnetic nanomaterials in adsorption of hexavalent chromium ion from water were studied in batch studies,including the pH,adsorption time,adsorbent dosage,initial concentration,enrichment multiple and regeneration performance.The mechanism,thermodynamics and dynamics of the Cr(VI)adsorption were also discussed.The adsorption behavavior of Cr(VI)onto the Fe3O4@Vc magnetic nanomaterials show that the pH is between 1-2,the highest removal efficiency was obtained,the time reached adsorption equilibrium is 80 min.When the pH is 1.5 and adsorption time is 80 min,under the given experimental condition,the best for the amount of adsorbent is 60 mg and optimal initial concentration is 150 mg/L.Adsorbed Cr(VI)was desorbed with 0.25 mol/L HCl to investigated the renewable properties of the Fe3O4@Vc magnetic nanomaterials.Langmuir model was well describes the adsorption of Cr(VI)in water by Fe3O4@Vc magnetic nanomaterials.Adsorption process can be promoted at higher temperature.The adsorption was consistent with the HO second-order kinetic model.The Cr(VI)maximum adsorption capacity of Fe3O4@SiO2 magnetic nanomaterials is 21.36 mg/g and adsorption time is 5 h to reach the equilibrium.The highest adsorption efficiency was obtained when the pH is around 3.Adsorbed Cr(?)could be eluted with HCl which the concentration is 0.5 mol/L and the enrichment multiple was 12,the renewable cycles was 8.Which shows that the Fe3O4@SiO2 magnetic nanomaterials has strong ability of recycling.The adsorption equilibrium data were better served the Langmuir model and the HO second-order kinetic model.The adsorption behavavior of Cr(?)onto the Fe3O4@SiO2@CS magnetic nanomaterials show that the adsorption rate can be up to 85%at the pH of 3,amount of magnetic nanomaterials of 50 mg,initial concentration of 180 mg/L,adsorption time of 120 min with a maximum adsorption capacity of 44.27 mg/g for Cr(?).Adsorbed Cr(?)could be eluted with HCl which the concentration is 0.5 mol/L and the enrichment multiple was 14,the renewable cycles was 9.Which shows that the Fe3O4@SiO2@CS magnetic nanomaterials have strong ability of recycling.The Freundlich model was more favorable than the Langmuir model,and raising temperature is beneficial to the adsorption.The kinetics process can be described by the HO second-order kinetic equation.The recovery rate of Fe3O4@Vc,Fe3O4@SiO2 and Fe3O4@SiO2@CS were respectively 94.67%?99.78%,97.67%?100.22%and 98.78%?101.00 in the environmental samples.The results showed that the three kinds of functionalized magnetic nanomaterials had good adsorption on Cr(?)in environmental samples.Among them,Fe3O4@SiO2@CS magnetic nanomaterials have better adsorption on Cr(?)than Fe3O4@Vc magnetic nanomaterials and Fe3O4@SiO2 magnetic nanomaterials.