Copper Hexacyanoferrate Composite For Cesium Removal From Aqueous Solution

With the progress of society and the development of industrialization,nuclear energy is gradually popularized as available energy.However,a large amount of radioactive waste from nuclear power plants poses a great threat to human health and the environment.Radioactive cesium is one of the main pollutants in wastewater,which will cause great harm to human health because of its long half-life,high activity,high stability and high solubility.Therefore,how to remove cesium ions from wastewater efficiently and economically has been paid more attention by rather researchers.In this paper,a variety of copper hexacyanoferrate composites were prepared by high efficiency and economic adsorption.SBA-15,biochar and magnetic biochar were used as substrate materials and copper ferricyanide as the main adsorbent.Scanning electron microscope?SEM?,X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FT-IR?,specific surface analysis?BET?,and X-ray electron spectroscopy?XPS?were used to analyze the microstructure and macroscopic properties of CuHCF composites.It is applied to the removal of cesium from simulated waste water.The removal effect of the prepared material on cesium is measured by the adsorption capacity or removal efficiency,and the removal mechanism for cesium by the CuHCF composite material is revealed.The results and conclusions are as follow:1.In this research,the copper hexacyanoferrate/SBA-15 composite was prepared by in situ deposition,which was further characterized using scanning electron microscope,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,Brunauer–Emmett–Teller,transmission electron microscopy and X-ray diffraction.The effects of different factors such as pH,temperature,contact time,initial cesium concentration on adsorption were studied.The pH significantly influenced the adsorption.The pseudo second-order kinetic model fitted the adsorption well,indicating chemisorption.The Langmuir isotherm proved that the adsorption happened on monolayer and the maximum adsorption capacity was determined as 0.123 mmol/g.The result showed that CHCF/SBA-15 could be directly used to adsorb cesium from aqueous solution.2.A microporous composite?CuHCF/PP600?for cesium removal was successfully prepared by copper hexacyanoferrate?CuHCF?dispersed into a biochar?pomelo peel was carbonized at 600°C?.In comparison with CuHCF/PP600 and pure CuHCF,it was showed that CuHCF/PP600 had better performances on sedimentation and cesium removal.The maximum removal efficiency of cesium by the composite is30.06 mg/g?at pH 7.0?.Adsorption kinetic and isotherm of CuHCF/PP600 were followed to Langmuir isotherm model and pseudo-second-order kinetic model respectively.Thermodynamic analysis shows that the adsorption process was endothermic.The removal efficiency of Cs⁺was down less than 5%in the presence of Na⁺,K⁺,Mg²⁺.The results indicate that CuHCF/PP600 is a promising adsorbent for cesium removal from aqueous solution.3.Composite CuHCF-MPC applied for cesium removal from water was prepared through copper hexacyanoferrate?CuHCF?immobilized into a magnetic pomelo peel biochar?MPC?.Compared with microporous composite CuHCF-PC?CuHCF immobilized into a pomelo peel biochar?PC??,the magnetic Fe₃O₄ particles embedding make CuHCF-MPC composite exhibit more excellent adsorption capacity?145.65mg/g?towards cesium and easy separation from water through an applied magnetic field.The PC with large specific area facilitated the dispersion of CuHCF.The adsorption of cesium by CuHCF-MPC can be completed in 90 min?95%removal for50mg/L Cs⁺?.Moreover,the adsorption process is exothermic and follows the pseudo-second-order kinetic model and Langmuir isotherm model.Importantly,CuHCF-MPC still maintain high selectivity and stability in groundwater and seawater.Adsorption property of Cs⁺by CuHCF-MPC is still stable under acidic and alkaline conditions.