High Li-Ion Selectivity of Five-Coordinate Layered Titanate K<sub>2</sub>Ti<sub>2</sub>O<sub>5</sub>
High Li-Ion Selectivity of Five-Coordinate Layered Titanate K<sub>2</sub>Ti<sub>2</sub>O<sub>5</sub>
复制标题
五配位层状钛酸盐K<sub>2</sub>Ti<sub>2</sub>O<sub>5</sub>的高锂离子选择性
DOI：
10.1021/acs.langmuir.2c02443
复制
发表时间：
2022
期刊：
影响因子：
3.9
通讯作者：
Teshima Katsuya
中科院分区：
文献类型：
--
作者：
Hayashi Fumitaka;Tatewaki Nanako;Sudare Tomohito;Terashima Chiaki;Teshima Katsuya
离子交换剂的选择性在资源回收和环境修复中有着特殊的应用，是吸附科学中的一个重要课题。在这项研究中，亚毫米尺寸的五配位K2 Ti 2 O 5（KTO）晶体的阳离子交换性能进行了论证。吸附等温线的测量上进行离子交换的KTO晶体与碱金属阳离子，包括Li+，Na+，Rb+，和Cs+。Li+、Na+、Rb+和Cs+在KTO上的最大吸附量分别为2.70、1.15、0.59和0.42 mmol g-1，这与常规离子交换剂（包括粘土和有机树脂）的“正常”选择性顺序（Cs+> Rb+> K+> Na+> Li+）相矛盾。Li+和Cs+交换实验的Kielland图显示了KTO上的优先Li+吸附，这支持了高Li+选择性。M+交换的KTO（M = Li、Na、Rb和Cs）的层间距取决于阳离子类型。KTO样品的拉曼和X射线吸收近边结构光谱分析表明，KTO中的某些Ti物种发生水解，从而在离子交换过程中在KTO表面上形成羟基。本文根据实验表征结果讨论了KTO高Li+选择性的来源。
Selectivity of ion exchangers is an important topic in adsorption science owing to its specific application in resource recovery and environmental remediation. In this study, the cation exchange property of the submillimeter-sized five-coordinate K2Ti2O5(KTO) crystals is demonstrated. Adsorption isotherm measurements were performed on KTO crystals ion-exchanged with alkali metal cations including Li+, Na+, Rb+, and Cs+. The maximum adsorption amounts of Li+, Na+, Rb+, and Cs+on KTO were 2.70, 1.15, 0.59, and 0.42 mmol g–1, respectively, which is contradictory to the “normal” selectivity sequence (Cs+> Rb+> K+> Na+> Li+) of conventional ion exchangers, including clays and organic resins. The Kielland plots for the Li+and Cs+exchange experiments showed preferential Li+adsorption on KTO, which supports the high Li+selectivity. The interlayer distance for M+-exchanged KTO (M = Li, Na, Rb, and Cs) was dependent on cation type. Raman and X-ray absorption near-edge structure spectroscopic analyses of the KTO samples indicated that certain Ti species in KTO underwent hydrolysis, and thereby formed hydroxyl groups on the KTO surface during ion exchange. The origin of the high Li+selectivity of KTO is discussed herein based on experimental characterization results.