基于表面离子印迹氧膦配体短通道介孔硅梯度交联膜的制备及提取铀的性能研究

Extraction of uranium from Radioactive Waste Liquid (RWL), which can obtain uranium resources for nuclear energy and reduce the environmental pollution, has a remarkable significance to the sustainable development of the nuclear industry. Adsorption separation technology has broad application prospects in extraction of uranium from RWL. Neutral alkylphosphine oxide was used as extractant for uranium extraction from solutions by solvent extraction. It has the advantage of high selectivity for uranium in high acidity and wide pH ranges. However, after fixed on adsorbent matrixes, two monodentate alkylphosphine oxide ligands are difficult to contact one uranyl ion at the same time, because of their unsuitable or unoptimizable surface distribution and spatial conformation. .The present work aims to develop novel surface uranyl ion-alkylphosphine oxide ligands imprinted rigid short channel mesoporous silica to solve this problem. The imprinted silica nano-particles will be embedded into gradiently crosslinked polyether-ether-ketone membranes for extraction of uranium from RWL. Such composite membranes integrate the advantages of the outstanding specificity and accessibility of the imprinted alkylphosphine oxide ligands, the rapid mass transfer in the three-dimensional microporous network of membrane and the short mesoporous channel of silica, the excellent chemical/irradiation/mechanical stability of gradiently crosslinked membranes and the synergistic effect of ketone ligands in the membrane matrixes for uranyl ion transfer. .The coordination mechanism for the imprinted ligands will be explored by different spectroscopic methods including Extended X-Ray Absorption Fine Structure (EXAFS) and Computational Simulation. The model for uranium transfer in the membranes will be built. The mechanism of gradiently crosslinked structure to keep the stabilized dispersion of silica nano-particles in the composite membrane matrixes will be studied..The present work will provide a better understanding of the interaction mechanism between metal ion and immobilized monodentate organic ligands. And it will also lay a new technological base for uranium extraction from aqueous uranium resources.

放射性废液中铀资源的提取对于核能可持续发展具有重要意义。利用固液分离的吸附技术提取液相中的铀资源具有广阔的应用前景。中性烷基氧膦配体，可在高酸度的含铀废液中，特异性的配位铀酰离子；然而将单齿的氧膦配体键合于固相吸附骨架后，因不合适的表面分布和构象，配体有效利用率低。为利用中性烷基氧膦配体的优势，本项目拟采用离子印迹氧膦配体的思想，先将印迹配合物嫁接到机械强度高的介孔硅骨架上，以形成并保持优化的配体分布和空间构象；再将印迹介孔硅复合于高稳定性的聚醚醚酮膜中，利用膜的酮基和三维微孔孔道与介孔硅孔道相互耦合，实现铀的高效传质和选择性配位吸附；最后对膜两侧进行梯度交联，强化介孔硅微粒在膜中的稳定分散性。阐明固化的氧膦配体的分布和构象与铀酰离子选择性配位的机理和构效关系，建立铀酰离子在膜型吸附剂中的传质和反应模型，明确膜的梯度交联结构对介孔硅的稳定性分散机制，为液体资源中铀的高效提取提供新方法。

放射性废液中金属离子的高效提取和分离，对核能和环境的可持续发展具有重要意义。中性氧膦配体可在酸性溶液中配位锕系元素，然而将单齿的氧膦配体键合于固相吸附骨架后，因不合适的表面分布和构象，配体有效利用率低。本项目通过对吸附剂骨架的结构调控和精准铆合氧膦配体，优化了载体骨架结构和氧膦配体分布及构象，使得配体 “物尽其用”，大幅度提高了氧膦吸附材料在酸性废水中对铀的吸附性能。探明了载体骨架中氧膦配体的分布状况，以及配体与铀酰离子的配位机理；研究了载体的孔结构与配体利用率之间的关系；掌握了吸附剂中铀酰离子的扩散、传质和反应规律，以及吸附材料稳定性的影响机制；为酸性放射性废水中铀的高效吸附提取开发了高效的吸附剂。项目还开发了新型的具有氧膦/硫膦配体的多孔硅基有机—无机复合吸附材料，系统研究了客体核素与吸附剂框架之间的相互作用规律，有望用于核素的高效捕集。此外，项目成功研制出具有阳离子选择分离性能的复合膜材料，包括有机金属框架纳米复合膜以及富含中性氧膦配体萃取体系的聚合物包含液膜，阐明了其分离金属离子的选择性机理，有望推动膜分离技术在放射性废液处理领域的应用。