Preparation Of Magnetic Ferrous Cyanide Materials And Removal Of Cesium And Cadmium

With the development of the world economy,the application of heavy metals has become increasingly widespread,resulting in an increasing amount of wastewater.Cadmium（Cd）,as the most severely polluted heavy metal currently,can cause serious damage to organs such as the kidneys in the human body.With the development of industry,the demand for energy has also increased.The gradual depletion of nonrenewable energy has shifted human attention to nuclear energy,and the development and utilization of nuclear energy is accompanied by the generation of radioactive wastewater.Cesium（Cs）,as a widely influential element in radioactive wastewater,has attracted more attention due to its highly soluble nature in water.Cs can cause various diseases in the human body.The production of reaction rod required for nuclear reaction requires Cd.In case of a nuclear accident,both Cd and Cs will enter the generated nuclear waste.Currently,Japan has measured the presence of these two elements in the same water,so how to effectively remove Cs and Cd from wastewater has become a key issue.Adsorption method has become the most widely used wastewater treatment method due to its high efficiency and easy recovery.This article selects the common adsorbent potassium ferrocyanide（K₄Fe（CN）₆）and loads it on triton tetroxide（Fe₃O₄）to synthesize a composite material（K₄Fe（CN）₆@Fe₃O₄）,exploring its adsorption capacity and mechanism for Cs and Cd in wastewater.（1）The synthesized K₄Fe（CN）₆@Fe₃O₄ was characterized by XRD,FTIR,SEM,TEM,XPS,and hysteresis loops.According to the XRD spectrum,the characteristic peaks of the material include the characteristic peaks of K₄Fe（CN）₆ and Fe₃O₄,and the intensity of the characteristic peaks has been enhanced.The FTIR spectrum contains typical characteristic peaks of K₄Fe（CN）₆ and Fe₃O₄.From the SEM and TEM spectra,Fe₃O₄ is spherical,and the surface of the material becomes smooth after loading K₄Fe（CN）₆.After loading K₄Fe（CN）₆,the material’s magnetism weakens,but it still exhibits strong magnetism.The characteristic peaks of K₄Fe（CN）₆ and Fe₃O₄ can be observed from the XPS spectrogram.The characterization results indicate that K₄Fe（CN）₆ has been successfully loaded onto Fe₃O₄,and after synthesis,it exhibits extremely strong magnetism,proving that K₄Fe（CN）₆@Fe₃O₄ can be separated from aqueous solution using an external magnetic field.（2）The removal of Cs from wastewater was carried out using K₄Fe（CN）₆@Fe₃O₄.The experimental results indicate that the removal of Cs by K₄Fe（CN）₆@Fe₃O₄ can adapt to a wide pH range,proving its applicability to different water bodies.The maximum adsorption capacity of K₄Fe（CN）₆@Fe₃O₄ obtained from the experiment is9.83 mg/g.The presence of coexisting ions in water has little impact on K₄Fe（CN）₆@Fe₃O₄ removal efficiency.The adsorption of Cs by K₄Fe（CN）₆@Fe₃O₄conforms to the quasi second-order kinetic model and Langmuir isotherm model,proving that the adsorption process of the material is monolayer chemical adsorption.After five cycles,the removal rate decreased from 98.69%to 80.35%,proving that the K₄Fe（CN）₆@Fe₃O₄ has good reusability.The adsorbed K₄Fe（CN）₆@Fe₃O₄,it was found that the adsorption mechanism of K₄Fe（CN）₆@Fe₃O₄ for Cs is mainly ion exchange.Cs in water replace K in K₄Fe（CN）₆ to achieve the removal effect.（3）The removal of Cd from water was carried out using K₄Fe（CN）₆@Fe₃O₄.The experimental results show that K₄Fe（CN）₆@Fe₃O₄ can effectively remove Cd under acidic conditions,with a removal efficiency of 98.88%at pH=6.Cd can be quickly removed within the first 10 minutes.The removal effect is basically not affected by coexisting ions.After five cycles,the removal efficiency decreased from the initial close to 100%to 87.01%.The adsorption process of K₄Fe（CN）₆@Fe₃O₄ conforms to the quasi second-order kinetic model and the Freundlich isothermal model.The adsorption mechanism of K₄Fe（CN）₆@Fe₃O₄ mainly involves ion exchange and electrostatic interactions,with Cd replacing K and Fe₃O₄ exhibiting electrostatic adsorption on Cd.The material can simultaneously remove Cs and Cd from water.In summary,K₄Fe（CN）₆ and Fe₃O₄ have good removal effects on both cesium and cadmium,and the experiments provide a detailed analysis of the adsorption effect and adsorption mechanism of the materials,which provides a theoretical basis for reference in practical applications.