Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
State Key Laboratory of Marine Resource Utilization in South China Sea, School of Biomedical Engineering, Hainan University, Haikou 570228, China.
J Hazard Mater. 2022 Jun 15;432:128695. doi: 10.1016/j.jhazmat.2022.128695. Epub 2022 Mar 12.
Uranium extraction from seawater is particularly significant and regarded as an indispensable strategy for satisfying the increasing demand for nuclear fuel owing to the high uranium reserves (about 4.5 billion tons) in seawater, while remains great challenges due to the low concentration, the interference of various cations and the complexity of the marine environment. Thus, developing a highly efficient adsorbent with high adsorption capacity, excellent selectivity, low cost, and facile synthesis method is significant and urgently required. Inorganic materials show many advantages in adsorption such as low cost, fast response, high stability, etc, while conventionally, have poor capacity and selectivity especially in real seawater. Herein, mesoporous CaCO (mCaCO) with vaterite phase is synthesized by a facile nanoemulsion strategy and "ready-to-use" for uranium adsorption without functionalization and post treatment. Surfactant Pluronic F127 not only assembles into reverse micelles to form mesopores, but also stabilizes the active vaterite phase. The obtained mCaCO with high surface area (48.2 m/g), interconnected mesopores (11 nm), and unique vaterite phase achieves highly efficient uranium adsorption with a maximum adsorption capacity of 850 ± 20 mg-U/g in uranium-spiked seawater and 6.5 ± 0.5 mg-U/g in 700 L of natural seawater for one week, as well as excellent selectivity, matching the state-of-the-art U adsorbents. After adsorption, mCaCO-U is dissolved with a simple acid elution to obtain concentrated uranyl solution for purification, avoiding the disposal of adsorbents. To the best of our knowledge, this is the first case to report mesoporous CaCO for uranium adsorption from seawater with such a good performance. The facile synthesis, abundant raw materials and eco-friendly adsorption-desorption processes endow the mCaCO as a promising candidate for large-scale uranium extraction from seawater.
从海水中提取铀具有重要意义，被认为是满足日益增长的核燃料需求的不可或缺的策略，因为海水中的铀储量（约 45 亿吨）很高，但由于浓度低、各种阳离子的干扰和海洋环境的复杂性，仍面临巨大挑战。因此，开发一种高效的吸附剂，具有高吸附容量、优异的选择性、低成本和简便的合成方法具有重要意义，也是迫切需要的。无机材料在吸附方面具有许多优势，如成本低、响应快、稳定性高等，但通常在实际海水中的容量和选择性较差。在此，通过简便的纳米乳液策略合成了具有文石相的介孔 CaCO（mCaCO），无需功能化和后处理即可“即插即用”用于铀吸附。表面活性剂 Pluronic F127 不仅组装成反胶束以形成介孔，而且还稳定活性文石相。所得到的具有高比表面积（48.2 m/g）、互联介孔（11nm）和独特文石相的 mCaCO 可实现高效的铀吸附，在含铀的海水中的最大吸附容量为 850±20mg-U/g，在 700L 的天然海水中吸附一周后为 6.5±0.5mg-U/g，以及优异的选择性，与最先进的 U 吸附剂相匹配。吸附后，mCaCO-U 用简单的酸洗脱溶解，以获得浓缩的铀溶液进行纯化，避免了吸附剂的处理。据我们所知，这是首例报道介孔 CaCO 用于从海水中吸附铀的案例，具有如此良好的性能。简便的合成、丰富的原料和环保的吸附-解吸过程使 mCaCO 成为从海水中大规模提取铀的有前途的候选材料。
