Heat Treatment Of Natural Magnetite And Its Adsorption Of Heavy Metal Ions

In recent years,with the rapid development of China’s economy,environmental pollution has attracted more and more attention.The construction of a large number of tailings ponds,under the rain leaching of heavy metal pollutants and mineral dressing agents can penetrate into the groundwater,to the surrounding people’s life and health has brought a great threat.Permeable reactive grid,as an effective means of groundwater pollution control,has been initially applied in China.One of the key problems affecting its large-scale application is the development of highly efficient adsorbent materials.Magnetite is a kind of metal adsorption material with excellent performance,which has been paid more and more attention.This paper in the key project of national natural science foundation of "more complex metal mine tailings leachate pollutants in situ repair and mechanism research",supported by the natural magnetite conducted a thermal modification,and its characterization,structure and properties were studied magnetite heat the heavy metal ions adsorption behavior of modified products,to explore the optimum modification conditions and test methods.1.The adsorption performance of magnetite for different metal ions was explored.The results show that magnetite has certain adsorption capacity for Pb,Cu and Mn ions,and the saturated adsorption capacity is 19.8 mg/g,12.0 mg/g and 1.7 mg/g,respectively.The adsorption of lead ions by magnetite accords with Freundlich model,and the adsorption of copper ions and manganese ions accords with Langmuir model.2.Thermal modification can significantly improve the ability of magnetite to adsorb heavy metal ions.The magnetite is gradually transformed into hematite by thermal modification in air atmosphere.After thermal modification in argon atmosphere,the phase is still magnetite.The potential of the two modified surfaces increased first and then decreased,and the saturated adsorption capacity of heavy metal cations decreased first and then increased.After thermal modification in air,the highest adsorption capacities of Pb,Cu and Mn ions are 14.1 mg/g,3.1mg/g and 9.5 mg/g,and the best adsorption effect of Cr(Ⅵ)is 0.5 mg/g.After thermal modification in argon,the maximum saturated adsorption capacity of the three cations is increased to 25.0 mg/g,4.0 mg/g,14.0 mg/g,and the saturated adsorption capacity of Cr(Ⅵ)is1.0 mg/g.This is mainly due to the thermal modification in argon atmosphere,the surface of magnetite produced a large number of holes,increasing the active sites.3.The dynamic adsorption of natural and modified magnetite was studied.Compared with the raw ore,the life of the thermally modified magnet ore in argon atmosphere was significantly improved.The adsorption life of manganese ion was increased from 33.5 to 47.0 PV,and the adsorption life of copper ion was increased from 80.8 to 165.0 PV.The adsorption life of lead ions increased from 98.4 to 176.0 PV,and the dynamic adsorption performance of three metal ions was excellent.