The removal and recovery of radioactive Sr(II) from wastewater and seawater has been of great concern due to the negative environmental impacts of nuclear energy development and the potential risk of nuclear accidents. Herein, a facile molten salt synthesis strategy was developed to systematically investigated the reaction of different types of MXenes with nitrates. Among the products, K intercalated hierarchical titanate nanostructures (K-HTNs) obtained from the direct chemical transformation of multilayered TiCT exhibited unique layered structures, good physicochemical properties, and outstanding adsorption performance for Sr(II). The maximum adsorption capacity of Sr(II) by K-HTNs reached 204 mg·g at ambient temperature, and the good regeneration and reusability of the titanate was also demonstrated. K-HTNs showed preferential selectivity for Sr(II) in different environmental media containing competing ions, and the removal efficiency of Sr(II) in real seawater was as high as 93.3 %. The removal mechanism was elaborated to be the exchange of Sr with K/H in the interlayers of K-HTNs, and the adsorbed Sr(II) had a strong interaction with Ti−O termination on the titanate surface. Benefiting from the merits of rapid and scalable synthesis and excellent adsorption performance, MXene-derived K-HTNs have broad application prospects for the purification of Sr-contaminated wastewater and seawater.

中文翻译：

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熔盐合成 MXene 衍生的分级钛酸盐以有效去除锶

由于核能发展对环境的负面影响和核事故的潜在风险，废水和海水中放射性Sr(II)的去除和回收一直受到高度关注。在此，开发了一种简便的熔盐合成策略来系统地研究不同类型的 MXene 与硝酸盐的反应。其中，由多层TiCT直接化学转化得到的K插层分级钛酸盐纳米结构（K-HTN）表现出独特的层状结构、良好的物理化学性能以及对Sr(II)的出色吸附性能。 K-HTNs在常温下对Sr(II)的最大吸附容量达到204 mg·g，并且钛酸盐具有良好的再生和重复使用性。 K-HTNs在含有竞争离子的不同环境介质中对Sr(II)表现出优先选择性，实际海水中Sr(II)的去除效率高达93.3%。去除机制被阐述为Sr与K-HTNs层间中的K/H的交换，并且吸附的Sr(II)与钛酸盐表面的Ti−O末端具有强烈的相互作用。得益于快速、可规模化的合成和优异的吸附性能，MXene 衍生的 K-HTN 在净化 Sr 污染废水和海水方面具有广阔的应用前景。