The Preparation Of Magnetic Fe₃O₄ Composites And The Removal For Heavy Metal Ions

Large amounts of heavy metal wastewater will be generated in industrial activities,their random discharge have a bad effect on the water quality and andorganism.Therefore,there is an urgent need to design and prepare high-efficiency adsorbents for the treatment of heavy metal ion pollution.Based on the characteristics of magnetic Fe3O4,such as easy separation,low toxicity and easy preparation,it has become the focus of research in the field of water environmental remediation.In this thesis,two kinds of magnetic Fe3O4 composites were successfully prepared,and their characterization was analyzed systematically.The removal of heavy metal ions from aqueous solution by magnetic Fe3O4 composites was investigated by macro-static adsorption experiments,the mechanism of interaction between heavy metal ions and adsorbents was investigated by microscopic spectrum analysis at atomic level.In the study,dopamine and Fe3O4 particles were functionally combined to prepare a core-shell structured magnetic material(Fe3O4@PDA),and the properties of Fe3O4@PDA physical chemistry were investigated by various characterization techniques.Fe3O4@PDA display large surface area,good stability and high saturation magnetization.The effects of environmental factors on the adsorption of Cd(Ⅱ)were studied;Fe3O4@PDA shows excellent removal ability for Cd(Ⅱ);The quasi second order kinetic has high applicability to the entire adsorption process;In addition,after many adsorption-desorption cycles,Fe3O4@PDA still maintain high adsorption performance.These findings provide a new adsorbent for the separation of Cd(Ⅱ)ions from aqueous solutions.The material containing sulfur atoms has high efficient selective adsorption for Cr(Ⅵ)and Pb(Ⅱ).In this thesis,the magnetic adsorbent(Fe3O4@PEI@MoS2)with flower-like structure were successfully synthesized.The hard-soft acid-base theory shows that the S atom on MoS2,as a soft base,can form a high degree of complexation with metal ions including Pb(Ⅱ).The Langmuir model can fit the adsorption process of Cr(Ⅵ)and Pb(Ⅱ)well,indicating that the adsorption sites are uniformly distributed during the adsorption process of Cr(Ⅵ)and Pb(Ⅱ);The quasi second order kinetic has high applicability to the entire adsorption process;Its excellent magnetic properties enable it to be separated and collected from aqueous solution with high repeatability.The removal mechanism of Cr(Ⅵ)and Pb(Ⅱ)by Fe3O4@PEI@MoS2 was investigated by macroscopic experiments and microscopic characterization techniques.The results show that the removal of Cr(Ⅵ)is mainly dominated by the reduction of Cr(Ⅵ)to Cr(Ⅲ),and the removal of Pb(Ⅱ)is mainly dominated by the complexation of Pb(Ⅱ)with sulfur-containing atoms.This study provides a new idea to remove Cr(Ⅵ)and Pb(Ⅱ)from actual wastewater.