Preparation Of Magnetic Metal Oxide Nanocomposites For The Adsorption Of Heavy Metal Ions And Dyes From Aqueous Solution

Nowadays,the shortage of water resources has become one of the most common problems all over the world.Unfortunately,with the rapid development of modern industry and agriculture,the industrial waste water discharged in environment has made the problem of water pollution more and more serious.Especially the contamination of heavy metals and organic dye caused the attention of people because they will bring great harm to human health and ecological environment.Therefore,the removal of heavy metals and organic dyes from wastewater is of great significance for the protection of human health and the restoration of ecological environment.Adsorption has been widely used in water pollution control due to its simple operation,low cost and wide range of adsorbent.Recently,magnetic materials have attracted much interest due to their unique magnetic properties.In this paper,three different kinds of magnetic metal oxide nanomaterials were successfully synthesized by different methods.Meanwhile the adsorption performance of these materials removing heavy metal or dyes was also investigated.The main contents and results are as following:(1)Hydrothermal synthesis of MnFe2O4 nanospheres using FeCl3·6H2O and Mn(CH3COO)2·4H2O as raw material and ethylene glycol as solvent.MnFe2O4@C composites were successfully synthesized using glucose as carbon source.The synthesized MnFe2O4@C composites were examined by SEM and TEM.The as-obtained products are all spherical with diameters ranging from 200 to 300 nm and with a uniform carbon layer about 3-5 nm in thickness.The adsorption performance of the MnFe2O4@C composites removing Cu(Ⅱ)and Pb(Ⅱ)were also investigated.The results showed that when the solution pH is 8,the removal efficiencies of MnFe2O4@C composites were 93.9%for Cu(Ⅱ),and 98.2%for Pb(Ⅱ),respectively.Besides,the results showed that the regeneration of adsorbent,after 3 cycles,the removal efficiencies of MnFe2O4@C composites were above 80%for Cu(Ⅱ),and 90%for Pb(Ⅱ),respectively,with slight reduction.(2)ZnFe2O4 nanospheres were obtained using Zn(CH3COO)2·2H2O and FeCl3·6H2O as raw material and ethylene glycol as solvent by a facile hydrothermal method.The synthesized ZnFe2O4@C was systematically characterized by XRD,N2 adsorption,FT-IR,VSM,Raman,SEM and TEM techniques,then tested as a magnetic-response absorbent for removal of cationic dyes(methylene blue,MB)from aqueous solution.The effects of initial solution pH,initial concentration and adsorption time were investigated.It was found that the magnetic ZnFe2O4@C adsorbent could effectively remove MB from aqueous solutions with a high removal effciency of nearly 100%at the optimized conditions.In addition,the adsorption isotherm is well fitted with the Langmuir equation,and the maximum adsorption capacity is 70.5 mg/g.(3)Fe3O4@C composites were successfully synthesized using FeCl3·6H2O as raw material and phenolic resin as carbon source under a solvothermal process.The structural characteristics of the product were investigated by XRD,FITR,N2 adsorption,VSM,Raman,SEM,TEM,and HRTEM.We used Fe3O4@C composites as a magnetic adsorbent to remove MB from aqueous solutions,and found that they exhibited excellent adsorption performance.The effects of initial solution pH,adsorbent dosage,initial concentration and adsorption time were investigated.The results indicated that the removal efficiency of MB was as high as 99%when the solution pH is 8,and the maximum adsorption capacity is 69.9 mg/g.The adsorption isotherm can be described well by Langmuir isotherm equation.