Adsorption Properties of Sr(II) on Zeolite Type Adsorbents and Their Irradiation Stabilities
Adsorption Properties of Sr(II) on Zeolite Type Adsorbents and Their Irradiation Stabilities
复制标题
沸石型吸附剂对Sr(II)的吸附性能及其辐照稳定性
DOI：
10.1115/icone22-30329
复制
发表时间：
2014
影响因子：
1.2
通讯作者：
M. Matsukura
中科院分区：
文献类型：
--
作者：
H. Mimura;Shunsuke Susa;Yoshiyuki Ito;Yasuo Saito;M. Matsukura
计划在LWTF（低放射性废物处理设施，JAEA）中对东海后处理设施产生的低放废物进行放射性废物处理。目标低放废物由高浓度硝酸钠（5 M NaNO 3）组成，含有低水平的90 Sr。本文采用间歇吸附法和柱吸附法研究了高功能A型分子筛（A51-JHP、A51-J（Union Showa）和A-4、X型分子筛（F-9））和钛酸-PAN（聚丙烯酰胺）对Sr ~（2+）的选择吸附性能。在模拟废液中（5MNaNO_3，0.1ppmSr ~（2+），~（85）Sr作示踪剂），比较了Sr ~（2+）在不同吸附剂上的分布特性。分配系数（Kd、Sr）的大小顺序为：钛酸-PAN> A51-JHP > A51-J > A-4 > F-9。钛酸-PAN的最大Kd，Sr值为218 cm ~ 3/g，而饱和容量（Qmax）很小。钛酸-PAN对Sr 2+离子的吸附速率最大，吸附在8h内达到平衡。另一方面，A51-JHP具有大于100 cm 3/g的相对大的Kd，Sr值和0.65 mmol/g的Qmax值。通过改变存在的阳离子（单一和混合溶液）和流速（0.08和0.17 cm 3/min）来检查Sr 2+的穿透性质。单一溶液的组分为400 g/L NaNO 3、100 ppm Sr 2+、作为示踪剂的85 Sr，并且混合溶液除了单一溶液组分之外还含有200 ppm Cs+、100 ppm Ca 2+、50 ppm Mg 2+、50 ppm RuNO 3+。单一溶液的穿透曲线呈S型，而混合溶液的穿透曲线出现C/C 0 = 1以上的“浓缩现象”。对于A51-JHP柱，单一溶液的穿透曲线与混合溶液的穿透曲线相似，降低流速可使5%折点增大，在~（60）Co照射下，A51-JHP柱的稳定性最高可达2.54MGy，Kd、Sr和Qmax值基本不变。相比之下，在0.28 MGy以上，由于PAN基体的辐解，钛酸-PAN的表面发生了变化，导致活性组分钛酸的释放，因此新型A型沸石（A51-JHP）有望用于LWTF中Sr 2+的选择性去除。在实际使用之前，应检查颗粒尺寸和流速的优化。Copyright © 2014 by ASME
Radioactive waste treatment is planned in LWTF (Low-level radioactive Waste Treatment Facility, JAEA) for LLW generated from the Tokai-reprocessing facility. The target LLW consists of highly concentrated sodium nitrate (5 M NaNO3) containing low-level 90Sr. In this study, selective adsorption properties of Sr2+ for highly functional A type zeolites (A51-JHP, A51-J (Union Showa) and A-4, X type zeolite (F-9) and Titanic acid-PAN (polyacrylamide) were clarified by batch and column adsorption methods. The irradiation stabilities of these adsorbents were also evaluated.The distribution properties of Sr2+ on different adsorbents were compared in simulated waste solution (5 M NaNO3, 0.1 ppm Sr2+, 85Sr as tracer). The order of distribution coefficients (Kd,Sr) was Titanic acid-PAN > A51-JHP > A51-J > A-4 > F-9. The largest value of Kd,Sr for titanic acid-PAN was estimated to be 218 cm3/g, while the saturated capacity (Qmax) was very small. Titanic acid-PAN had also the largest uptake rate of Sr2+ ions and the uptake attained equilibrium within 8 h. On the other hand, A51-JHP had a relatively large Kd,Sr value above 100 cm3/g and a Qmax value of 0.65 mmol/g.The breakthrough properties of Sr2+ were examined by varying cations present (single and mixed solutions) and flow rate (0.08 and 0.17 cm3/min). The components for the single solution were 400 g/L NaNO3, 100 ppm Sr2+, 85Sr as tracer, and the mixed solution contains 200 ppm Cs+, 100 ppm Ca2+, 50 ppm Mg2+, 50 ppm RuNO3+ in addition to the single solution components. The breakthrough curve for Titanic acid-PAN column using single solution had an S-shaped profile, while the “concentration phenomenon” exceeding C/C0 (breakthrough ratio) = 1 was observed in the case of mixed solution. As for the A51-JHP column, the breakthrough curve for single solution was similar to that for mixed solution and the 5% breakpoint was enhanced by decreasing the flow rate.The A51-JHP was stable under 60Co-irradiation up to 2.54 MGy; Kd,Sr and Qmax values were almost constant. In contrast, Titanic acid-PAN was affected above 0.28 MGy, due to the radiolysis of PAN matrix, and this surface alteration led to the release of active component of titanic acid.The novel A type zeolite (A51-JHP) is thus expected for the selective removal of Sr2+ in LWTF. The optimization of particle size and flow rate should be examined before practical use.Copyright © 2014 by ASME