Preparation and alkali metal ion exchange properties of protonated Rb8Nb22O59 compound
Preparation and alkali metal ion exchange properties of protonated Rb8Nb22O59 compound
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质子化Rb8Nb22O59化合物的制备及碱金属离子交换性能
DOI：
10.1021/cm050835e
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发表时间：
2005
影响因子：
8.6
通讯作者：
K. Ooi
中科院分区：
文献类型：
--
作者：
Xiaojing Yang;Y. Makita;Junji Hosokawa;K. Sakane;K. Ooi
以Rb8Nb22O59为原料提取Rb+，制备了离子交换剂H8Nb22O59·8H2O，并考察了其对碱金属离子的离子筛性能。在室温下，用浓HNO3溶液可以有效地提取Rb+，得到质子化化合物，其组成为Rb0.14H7.9Nb22O59·8.2H2O。质子化（水合氢离子形式）晶体的晶格参数（a = 7.5104（2)和c = 43.0780(8)）为六方对称，R3m）非常接近Rb+形式的前驱体。交换容量的增大顺序为Cs+≪Rb+ < K+, Na+ < Li+，这与离子半径的减小顺序一致。根据质子化化合物的组成计算得到Li+、Na+和K+的容量接近理论值2.55 mmol/g。测定了微量离子加载条件下碱金属离子的分布系数Kd。在pH值约为3时，选择性顺序为Cs+、Li+≪Na+ < Rb+≪K+；质子化后的样品对t…
An ion-exchanger H8Nb22O59·8H2O was prepared by extracting Rb+ from Rb8Nb22O59, and its ion-sieve properties for alkali metal ions were investigated. The Rb+ can be effectively extracted using a concentrated HNO3 solution at room temperature, leading to a protonated compound with composition of Rb0.14H7.9Nb22O59·8.2H2O. The protonated (hydronium ion form) crystal has the lattice parameters (a = 7.5104(2) and c = 43.0780(8) A of hexagonal symmetry, R3m), very close to the Rb+-form precursor. The exchange capacity increased in the order Cs+ ≪ Rb+ < K+, Na+ < Li+, which agrees with the decreasing order of ionic radius. The capacities for Li+, Na+, and K+ were close to the theoretical value of 2.55 mmol/g calculated from the composition of protonated compound. The distribution coefficients (Kd) of alkali metal ions were determined in the condition of microamount of ion loading. The selectivity sequence was Cs+, Li+ ≪ Na+ < Rb+ ≪ K+ at pH around 3; the protonated samples showed markedly high selectivity for t...