Efficient U(VI) Reduction and Sequestration by Ti2CTx MXene
Efficient U(VI) Reduction and Sequestration by Ti2CTx MXene
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Ti2CTx MXene 高效还原和封存 U(VI)
DOI：
10.1021/acs.est.8b03711
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发表时间：
2018-09-18
影响因子：
11.4
通讯作者：
Shi, Weiqun
中科院分区：
文献类型：
--
作者：
Wang, Lin;Song, Huan;Shi, Weiqun
虽然将高移动的U（VI）还原为低溶解度U（IV）长期以来一直被认为是原位环境修复铀的有效方法，但候选还原剂在很大程度上限于铁基材料和微生物。含钛化合物在天然铀矿床中的重要性表明了钛在铀迁移中的作用。在此，第一次，二维过渡金属碳化物，Ti 2CTx，显示出有效地去除铀通过吸附还原策略。批实验表明，TiC 2 Tx在很宽的pH范围内表现出优异的U（VI）去除，在pH 3.0时的吸收容量为470 mg g（-1）。利用X射线吸收光谱、衍射和光电子能谱等手段对Ti_2CTX还原U（VI）为U（IV）的反应机理进行了研究。低pH值下还原的U（IV）物质被鉴定为单核，与MXene底物结合。在接近中性的pH值下，UO 2 +x相的纳米颗粒吸附到基底上，其中一些Ti 2CTx转化为无定形TiO 2。随后的深入研究表明，Ti 2CTx材料可能是铀矿废水处理中可渗透反应屏障的潜在候选者。这项工作突出了由Ti 2CTx MXene还原诱导的U（VI）固定，包括pH依赖性还原机制，可能会促进钛基材料在消除其他氧化污染物中的应用。
Although reduction of highly mobile U(VI) to less soluble U(IV) has been long considered an effective approach to in situ environmental remediation of uranium, candidate reducing agents are largely limited to Fe-based materials and microbials. The importance of titanium-containing compounds in natural uranium ore deposits suggests a role for titanium in uranium migration. Herein, for the first time, a two-dimensional transition metal carbide, Ti2CTx, is shown to efficiently remove uranium via a sorption reduction strategy. Batch experiments demonstrate that TiC2Tx exhibits excellent U(VI) removal over a wide pH range, with an uptake capacity of 470 mg g(-1) at pH 3.0. The mechanism for U(VI) to U(IV) reduction by Ti2CTx was deciphered by X-ray absorption spectroscopy and diffraction and photoelectron spectroscopy. The reduced U(IV) species at low pH is identified as mononuclear with bidendate binding to the MXene substrate. At near-neutral pH, nanoparticles of the UO2+x phase adsorb to the substrate with some Ti2CTx transformed to amorphous TiO2. A subsequent in-depth study suggests Ti2CTx materials may be potential candidates for permeable reactive barriers in the treatment of wastewaters from uranium mining. This work highlights reduction-induced immobilization of U(VI) by Ti2CTx MXene including a pH-dependent reduction mechanism that might promote applications of titanium-based materials in the elimination of other oxidized contaminants.