水化层对于氧化石墨基海水提铀材料吸附性能影响及其调控机制

Uranium extraction from seawater (UES) is considered as an important approach to solve the shortage problem of uranium resource in our country, ensuring the sustainable development of nuclear power. However, it remains challenging to guide the development of uranium adsorption materials based on currently basic theory of the ion competition, which lacks necessary understanding to the regularity of UES. This seriously restricts the industrialization process of UES. The project introduces the hydration barrier theory and reveals the new ideas for the mechanism of uranium enrichment from seawater by adjusting the properties of surface hydration barrier of the adsorbent material. Graphite oxide (GO) is chosen as study subjects due to the facile modification and modelling calculating. More important, the substrate and morphology of GO hardly affect the adsorption performances. A series of graphite oxide-based materials would be prepared via chemical modification and recombination. The structural analysis, performance testing, real-sea testing and theoretical simulation will be performed, aiming to clarify the effect of material structure on the properties of hydration layer and UES, as well as the modulation mechanism of hydration shell by adjusting the material pKa and surface functional groups, and investigate the transformation of adsorption material for practical application for UES by the modulation mechanism of hydration shell. Based on above work, this project will provide the theoretical guidance for the development of UES.

海水提铀被认为是解决我国铀矿资源匮乏，保证核电可持续发展的重要途径，但由于缺少对海水提铀规律性认识，现有离子竞争理论对于海水提铀吸附材料的研发难以充分发挥导向作用，严重制约海水提铀产业化进程。本项目引入水化层屏障理论，提出通过调整吸附材料表面水化层性质揭示海水提铀机制的新思路。选取基底和形貌对于吸附性能影响小，易于改性复合和建模计算的氧化石墨作为研究对象，应用改性、复合等方法制备了系列氧化石墨基材料，通过结构分析、性能检测、实海测试和理论模拟方法，阐明材料结构对于水化层性质及海水提铀性能的影响规律，探究通过调整材料pKa和表面官能团方法对于水化层的调控机制，探索应用水化层调控机制实现铀吸附材料向海水提铀材料转化的途径，为海水提铀吸附材料的研发提供理论指导。

本项目在海水提铀研究中引入水化层屏障理论，以基底和形貌对于吸附性能影响小，易于改性复合和建模计算的氧化石墨作为研究对象，通过结构分析、性能检测和理论模拟等研究方法，阐明材料结构对于水化层性质及海水提铀性能的影响规律，探究通过调整材料pKa和表面官能团方法对于水化层的调控机制。分子动力学计算表明水溶液中氧化石墨烯表面的水分子间氢键形成高密度水化层。水化层中的部分水分子可以与氧化石墨烯的官能团相互作用，形成悬挂羟基。含氧官能团数量增加，悬挂羟基结构数量增加。且随着含氧官能团的增加，水合层变得更加稳定。水化层中水分子的竞争，极大地影响材料吸附性能。研究表明胍基聚合物、尿素改性单宁、胺肟功能化的二氨基马来腈等材料与氧化石墨烯复合，可以有效抑制水化层对吸附性能的影响。上述材料的pKa值大于8，依据多元混酸pKa值的计算规律，将其与氧化石墨烯复合后可以获得pKa值与海水pH值接近的复合材料。在海水环境下，在材料表面铀酰离子与水的羟基形成竞争，破坏水化层，导致复合材料最佳吸附pH值与海洋实际pH值接近，在海水中吸附性能得到提升。探索应用水化层调控机制实现铀吸附材料向海水提铀材料转化的途径，为海水提铀吸附材料的研发提供理论指导。