Selective Adsorption And Biotoxicity Of Cs(?) On Clay/ferrocyanide Composites

The nuclear accident in Fukushima,Japan in 2011 produced a large amount of radioactive wastewater,among which radionuclide ¹³⁷Cs was the main pollutant.Because of its long half-life and strong water solubility,it will pose a serious threat to the ecosystem.Therefore,how to efficiently remove Cs(I)from cesium-containing wastewater without generating new pollutants has become a research hotspot at present.Adsorption method is considered as a potential treatment method for cesium pollution due to its advantages of simple operation,economy and high efficiency,and the synthesis of highly effective adsorption materials is the key and difficult point in the field of radioactive wastewater treatment.In this paper,three different clay/ferrocyanide composites were prepared by in-situ synthesis,and the physical and chemical properties such as surface morphology,structure and composition of the composites were discussed by various characterization methods.The ability of adsorption materials to remove Cs(I)from simulated cesium-containing wastewater was studied by static adsorption experiments,and the adsorption mechanism was analyzed.The influence of p H on the stability of materials was discussed,and the stability mechanism was speculated.Through biological experiments,the toxicity and actual excretion promoting ability of the material were analyzed.The main research results are as follows:(1)The characterization results of Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)show that rectorite/potassium zinc ferrocyanide(MR/PZH),montmorillonite/potassium copper nickel ferrocyanide(MB/PBAS)and illite/copper ferrocyanide(MI/PCu)have been successfully prepared by hydrothermal method and in-situ synthesis technology.(2)MR/PZH and MB/PBAS have good chemical stability in a wide p H range,and the released FCN concentration meets the international water purification standard,and can maintain good stability when applied in actual seawater.The material is non-toxic to Hegp2 cells and has a certain promoting effect.MR/PZH can promote the excretion of Cs(I)in real organisms,and the excretion rate can reach 43%.(3)The loading of ferrocyanide can significantly improve the selective adsorption performance of clay materials for Cs(I).The maximum adsorption capacity of MR/PZH composite adsorption materials prepared in this work for Cs(I)at room temperature is210 mg/g,which is better than that of raw materials used in the synthesis process.The adsorption performance of materials for Cs(I)can be improved with the increase of temperature.The adsorption process can be well described by pseudo-second-order kinetics and accords with Langmuir isothermal adsorption equation.(4)MI/PCu@Pt partially loaded with platinum layer has good self-propelled performance,and the process of adsorbing Cs(I)in 5 wt%H₂O₂solution can be better described by pseudo-second-order kinetic model.Compared with the original material,the adsorption equilibrium time is greatly shortened,and the pseudo-second-order rate constant is 1.392 g/(mg·min),which is five times that of conventional materials.