Treatment Of Cs~+ Containing Simulated Liquid Radioactive Waste In Nuclear Power Plant By Transition Metal Hexaycnaoferrate Film Electrode

With the rapid development of nuclear power,the emissions of liquid radioactive waste from nuclear power plants continues to increase which causes serious damage to the environment and human health.Transition metal hexacyanoferrate is an inorganic coordination compound with unique three dimensional network structure.It shows great application value in liquid radioactive waste treatment owing to its strong adsorption capacity and high selectivity.The experiment took removal efficiency of Cs+ as the index,invesgating the effects of various conditions on the adsorption and potentiostatic desorption of Cs’ by PB,exploring the reaction mechanism and studying the preparation of MnHCF film electrodes and its Cs+ separation capacity preliminarily.It provides reference for metal hexacyanoferrate film electrodes applied to treatments of liquid radioactive waste.The experimental results were as follows:(1)The study of the preparation of PB film electrodes by potentiostatic method showed that:the film electrode prepared under the optimal condition was insoluble PB,indicating the presence of water molecules and lattice defects in the compound.This PB film electrode has the best adsorption capacity for Cs+,the removal rate reached 84.84%.(2)The study of the adsorption of Cs+ by PB film eletrodes showed that:When Cs+concentration was 1 mg/L and volume of liquid waste was 50 mL,the removal rate was 84.84%,the adsorption amount was 84.84 mg/g.When the mole ratio of Cs+:K+ was 1:1～1:20 or boric acid concentration(as B)was 0 mg/L～3000 mg/L,the presence of K+ and boric acid would influence the effect of Cs+ adsorption by PB film.The higher the concentration of K+ and boric acid,the greater the influence and the lower Cs+ removal rate would be obtained.(3)The study of adsorption mechanism shows that:The process of Cs+ adsorption by PB film were well described by the pseudo-second-order kinetic model and Langmuir adsorption model.This adsorption process both have physical adsorption and chemical adsorption with chemical adsorption as the main process.It is indicated that the adsorption is spontaneous,endothermic and entropy increasing process.The maximum absorption capacity of Cs+ by PB was 180.58 mg/g at 25 ℃ and pH 5.5.(4)The study of the potentiostatic desorption of Cs+ by PB/Cs film eletrodes shows that:under the optimal condition,the desorption rate reached 90.71%.CV,SEM,IR and EDS showed that the particle morphology and structure of PB/Cs were unchanged after desorption.In the desorption processes,FeⅡ-C=N-FeⅢ was oxidized to FeⅢ-C=N-FeⅢ.Meanwhile,Cs+could be released from the PB/Cs with the entry of Cl-into the crystalline structure,which gives rise to the oxidation of PB to PY.(5)The study of the preparation of MnHCF film electrodes and its Cs+ separation capacity shows that:the film electrode prepared under the optimal condition had reversible electrochemical behavior in 1 mol/L NaNO3 solution.It is good to separate Cs+ and the removal rate of adsorption Cs+ reached 64.98%by applying 0.2 V to oxidized state films.