Synthesis Of Prussian Blue Functionalized Materials For Cesium Adsorption

Energy demand is increasing with the development of social economy. In order to deal with the shortage of energy sources and environment problems, the development of nuclear power is at full speed in recent years. However, large quantities of radioactive waste will be produced in the process of power generation. If without proper treatment, the radioactive waste will threaten global environment and human health. As a major component of radioactive liquid waste, 137 Cs possesses relatively long half-life time(30 years) as well as high volatility, activity and solubility. In 2011 Fukushima Daiichi nuclear accident caused the leakage of plenty of radioactive liquid waste, especially 137 Cs. Therefore, the development of novel materials and techniques is of great importance for efficient removal of cesium from aqueous solution.It is well-known that Prussian blue and its analogues present a strong affinity for cesium ions. Actually Prussian blue had been effectively used to treat cesium exposure during the Chernobyl nuclear reactor accident. In this work, the property of Prussian blue, a strong affinity for cesium ions, was utilized. We synthesized Prussian blue functionalized composite materials to explore their application in cesium adsorption.Specific studies of this paper are as follows:(1) Synthesis of Prussian blue derivate-modified mesoporous material via click reaction for cesium adsorption.Pentacyano(4-vinyl pyridine)ferrate complex, Prussian blue derivate, was used as functional reagent reacting with thiol groups. Prussian blue derivate-modified SBA-15 was prepared by photoinitiated thiol-ene reaction between thiol modified SBA-15 and Prussian blue derivate in water at room temperature. Successful synthesis of SBA-15 displaying mesoporous structure was verified by TEM, and the mesopores remained after modification. The BET surface area decreased from 487 to 277 m2/g while pore diameter decreased from 8.7 to 5.8 nm. XRD patterns indicate that Prussian blue derivate exists in mesopores as amorphous state. The XPS spectra clearly show cesium peaks(Cs3d5 and Cs3d3) after adsorption.The effects contact time, coexisting ions, weight percent of Prussian blue derivate and initial concentration on cesium adsorption were investigated. The higher weight percent of Prussian blue derivate, the larger equilibrium adsorption amount would be obtained. The investigation of adsorption kinetics showed adsorption process that kinetically followed pseudo-second-order model. The adsorption of SBA-15@FC could reach equilibrium with a large adsorption capacity(qmax) of 13.90 mg/g within 2 h at 298.15 K, which is very high in comparison with the capacity reported previously. SBA-15@FC could be efficiently regenerated and reused with high adsorption efficiency after five cycles. Therefore, Prussian blue derivate-modified mesoporous material would be a promising material and could show a good performance of cesium adsortion from aqueous solutions.(2) Synthesis of Prussian blue temperature-sensitive copolymers for cesium adsorption.Pentacyano(4-vinyl pyridine)ferrate complex(VPFC) was firstly prepared for copolymerization. Then VPFC was used as monomer for the copolymerization with sulfobetaine methacrylate(SBMA). The copolymer can be crosslinked by adding Fe3+ to obtain Prussian blue temperature-sensitive copolymer. According to thermal gravimetric analysis, the molar fractions of SBMA and VPFC is about 1.31: 1. The upper critical solution temperature of copolymer was determined to be 62 oC by dynamic light scattering.The effect of contact time, temperature on cesium adsorption was investigated. The higher temperature, the better adsorption efficiency at pH 7 and 1.0 g/L of adsorbent dose. The adsorption process followed pseudo-second-order model. The adsorption could reach equilibrium within 6 h. This novel temperature-sensitive copolymer composite has a potential application in cesium adsorption from aqueous solutions.