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SELECTIVE ADSORPTION PROPERTIES AND STABLE SOLIDIFICATION OF CS BY INSOLUBLE FERROCYANIDE LOADED ZEOLITES

机译:不溶性氰铁盐负载型沸石对CS的选择性吸附性能和稳定凝固

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In Fukushima NPP-1, large amounts of high-activity-level water (HALW) accumulated in the reactor, turbine building and the trench in the facility is treated by circulating injection cooling system. The development of highly functional adsorbents and stable solidification method contributes to the advancement of the decontamination system and environmental remediation. The present study deals with (1) preparation of insoluble ferrocyanide loaded zeolites, (2) selective uptake of Cs~+ in seawater, (3) estimation of Cs immobilization ratio and stable solidification. Various kinds of Cs-selective composites loaded with insoluble ferrocyanides (CoFC, NiFC) into the zeolites (zeolite A (A51, A-51J), zeolite X (LSX), chabazite (modified chabazite) and natural mordenite (SA-5)) matrices have been prepared using successive impregnation/precipitation methods by Tohoku University. As for Cs~+ adsorption, these composites had relatively large uptake (%) above 95%, distribution coefficients (K_d) above 10~3 cm~3/g and excellent adsorption kinetics even in seawater. The immobilization ratio (%) of Cs for the CoFC saturated with Cs~+ was estimated at different calcination temperatures up to 1,200°C in advance. The immobilization ratio was less than 0.1% above 1,000°C, indicating that the adsorbed Cs~+ ions are completely volatilized and insoluble ferrocyanides had no immobilization ability for Cs. In contrast, the insoluble ferrocyanide-loaded zeolites had excellent Cs immobilization ability; in the case of insoluble ferrocyanide-loaded natural zeolites (NiFC-SA-5, CoFC-modified chabazite), the immobilization ratio was above 99% and 96% even after calcination at 1,000°C and 1,100°C,respectively, indicating that nearly all Cs ions are immobilized in the sintered solid form. On the other hand, the immobilization ratio for the insoluble ferrocyanide-loaded A and X zeolites (NiFC-A (A51, A51J), NiFC-X) tended to decrease with calcining temperature; for example, the immobilization ratio for NiFC-X at 1,000°C and 1,100°C was estimated to be 74.9% and 55.4%, respectively, and many spots concentrating Cs were observed on the surface. The difference in immobilization behavior between natural zeolites and synthetic ones is probably due to the phase transformation and surface morphology at higher temperature above 1,000°C. The stable solidification of insoluble ferrocyanides was thus accomplished by using the excellent Cs immobilization abilities of zeolite matrices (Cs trapping and self-sintering abilities).
机译:在福岛NPP-1中,通过循环注入冷却系统对反应堆,涡轮机建筑物和设施中的沟槽中积累的大量高活性水(HALW)进行处理。高性能吸附剂和稳定固化方法的发展为净化系统和环境修复的发展做出了贡献。本研究涉及(1)制备不溶性负载亚铁氰化物的沸石,(2)海水中Cs〜+的选择性吸收,(3)Cs固定率和稳定固化的估计。将各种不溶性亚铁氰化物(CoFC,NiFC)负载到沸石中的各种Cs选择复合材料(沸石A(A51,A-51J),沸石X(LSX),菱沸石(改性菱沸石)和天然丝光沸石(SA-5))东北大学使用连续的浸渍/沉淀法制备了基质。至于Cs〜+的吸附,这些复合材料在95%以上具有相对较大的吸收率(%),在10〜3 cm〜3 / g以上具有分布系数(K_d),即使在海水中也具有优异的吸附动力学。预先在高达1200°C的不同煅烧温度下估算了Cs对Cs〜+饱和的CoFC的固定化率(%)。在1000℃以上,固定化率小于0.1%,表明吸附的Cs〜+离子完全挥发,不溶性亚铁氰化物对Cs没有固定能力。相反,不溶性装载亚铁氰化物的沸石具有优异的Cs固定化能力。对于不溶性负载亚铁氰化物的天然沸石(NiFC-SA-5,CoFC改性菱沸石),即使在1,000°C和1,100°C煅烧后,固定化率也分别高于99%和96%。所有的Cs离子都以烧结的固体形式固定化。另一方面,负载有不溶性亚铁氰化铁的A型和X型沸石(NiFC-A(A51,A51J),NiFC-X)的固定化率随着煅烧温度的降低而倾向于降低。例如,据估计NiFC-X在1,000°C和1100°C的固定率分别为74.9%和55.4%,并且在表面上观察到许多Cs集中的斑点。天然沸石和合成沸石之间固定化性能的差异可能是由于在高于1000°C的较高温度下的相变和表面形貌所致。因此,通过使用优异的沸石基质的Cs固定能力(Cs捕获和自烧结能力),可以实现不溶性亚铁氰化物的稳定固化。

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