School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, Narmak, Tehran, 16846, Iran.
Nuclear Fuel Cycle Research School, Nuclear Science and Technology Research Institute, Tehran, Iran.
Environ Sci Pollut Res Int. 2024 Aug;31(40):53329-53347. doi: 10.1007/s11356-024-34773-x. Epub 2024 Aug 26.
Nanostructure titanium carbide MXene (TiCTx) was modified with KHPO and chitosan to effectively remove strontium from nuclear wastewater. Nuclear waste includes radionuclides of uranium, thorium, strontium, and cesium, which are classified depending on the concentration of radionuclides. Nuclear waste with a high strontium concentration is the production waste of radiopharmaceutical production centers. TiCTx was synthesized from TiAlC using HF40% and HF in situ (MILD-TiCT) in 24 h at 313.15 and 333.15 K. Morphology, structure, and functional groups were investigated using the XRD, SEM, EDS, FTIR, and BET analyses. The Sr(II)'s adsorption capacity on TiCT-HF and TiCT-HF in situ was obtained as 61.9 and 253.5 mg g, respectively (temperature, 298.15 K; pH, 7.00; contact time, 180 min; and Sr(II) concentration, 150 mg l). TiCT-HF in situ showed fourfold adsorption due to more hydroxyl functional groups and larger interlayer spacing. TiCT was modified with KHPO and chitosan to investigate the mechanism of change of Sr(II)'s adsorption capacity, which increased to 370 and 284 mg g, respectively. The structural results of modified TiCT showed that the surface functional groups increased when modified with chitosan. In addition, modification with KHPO, through encapsulating large amounts of KHPO between TiCT layers, increased the possibility of Sr(II) diffusion between layers and electrochemical interactions with hydroxyl groups, and thus, increased its adsorption. Some experiments were designed to investigate the effect of parameters like initial concentration of Sr(II), contact time, temperature, and pH solution, as well as modified- and unmodified-TiCT on adsorbent. The results revealed that the adsorption process of Sr(II) with pristine and modified-TiCT follows pseudo-second-order kinetics and Freundlich heterogeneous isotherm model. Freundlich model isotherm indicates the presence of various functional groups on the surface and between the pristine and modified TiCT layers. Electrostatic reactions and intra-sphere complexation were the two dominant mechanisms of the adsorption process.
纳米结构碳化钛 MXene（TiCTx）经过 KHPO 和壳聚糖改性，可有效去除核废水中的锶。核废料包括铀、钍、锶和铯的放射性核素，根据放射性核素的浓度进行分类。高锶浓度的核废料是放射性药物生产中心的生产废物。TiCTx 是通过 HF40% 和原位 HF（MILD-TiCT）在 313.15 和 333.15 K 下 24 小时合成的。通过 XRD、SEM、EDS、FTIR 和 BET 分析研究了形貌、结构和官能团。在 298.15 K、pH 值为 7.00、接触时间为 180 min、Sr(II)浓度为 150 mg l 的条件下，TiCT-HF 和 TiCT-HF 原位对 Sr(II)的吸附容量分别为 61.9 和 253.5 mg g。TiCT-HF 原位的吸附量增加了四倍，这是由于其具有更多的羟基官能团和更大的层间距。TiCT 经过 KHPO 和壳聚糖改性，以研究 Sr(II)吸附容量变化的机制，其吸附容量分别增加到 370 和 284 mg g。改性 TiCT 的结构结果表明，壳聚糖改性后表面官能团增加。此外，KHPO 的改性通过在 TiCT 层之间封装大量的 KHPO，增加了 Sr(II)在层间扩散和与羟基发生电化学相互作用的可能性，从而提高了其吸附能力。设计了一些实验来研究初始 Sr(II)浓度、接触时间、温度、pH 值溶液以及改性和未改性 TiCT 对吸附剂的影响。结果表明，原始和改性 TiCT 对 Sr(II)的吸附过程遵循准二级动力学和 Freundlich 非均相等温模型。Freundlich 等温模型表明，原始和改性 TiCT 表面和层之间存在各种官能团。静电反应和内球络合是吸附过程的两个主要机制。
