Cryptand Cages for Anion Selective Encapsulation for Nuclear Waste

用于核废料阴离子选择性封装的穴居笼

• 批准号: 2282151
• 金额: --
• 依托单位: University of Huddersfield
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2282151
• 关键词: Cryptand; Cages; Anion; Selective; Encapsulation

The reprocessing of spent fuels and the decommissioning of historical nuclear facilities generates a complex mixture of waste material that needs to rendered safe for long term storage and ultimate disposal. Some of the most difficult waste streams are those that contain oxyanions of toxic and radioactive elements, e.g. pertechnetate, selenite, selenate, chromate, molybdate, iodate, bromate.We propose a cost-effective removal strategy based on a novel selective encapsulation process using self-assembled cryptand cages. A pilot study on common anions (with different charge and morphology) demonstrated a fast recovery, reducing anions concentration from 1000 to <0.1ppm. This research was published in the high-impact journal Angewandte Chemie in 2018, and patent protection is under way. The removal can be engineered to work in extreme environments, highly acidic solutions and high ionic strength, producing stable encapsulation of anions either in solution or as crystalline precipitates. This has an advantage for liquid high-level waste pending vitrification, as the anions will be stabilized within the highly radioactive liquor. Our research vision is to attain controlled removal via immobilization using cryptand cages based on anion charge and morphology. Thus we need to determine the factors controlling the encapsulation and the precipitation: the nature of the cryptand (how changes in its design reflect in encapsulation), the metal center for the complex cage, the conditions of the liquid media (pH, ionic strength), and the kinetics of release. To define this complex relationship, we will employ a multidisciplinary approach that brings together the power of computational screening, experimental synthesis and characterization. This will accelerate the development of sustainable and cost-effective encapsulation strategies, reduce environmental impact and enhance waste form performance.We aim to support our hypothesis and to achieve the following objectives: (1) to synthetize ligands based on those previously reported but modulate the nature of the donor atoms and the size of the cavity, with a range of metal center to determine the factors controlling anion selectivity; (2) to identify the interactions between the cage and the anion to retard kinetic release; (3) to produce atomistic models of target structures using integrated experiments and modelling, and to characterize their stability, morphology, and composition.

乏燃料的后处理和历史核设施的退役会产生复杂的废料混合物，需要确保其安全，以便长期储存和最终处置。一些最困难的废物流是那些含有有毒和放射性元素的氧阴离子的废物流，例如。高锝酸盐、亚硒酸盐、硒酸盐、铬酸盐、钼酸盐、碘酸盐、溴酸盐。我们基于使用自组装穴状配体笼的新型选择性封装工艺，提出了一种经济高效的去除策略。对常见阴离子（具有不同电荷和形态）的初步研究表明，可以快速恢复，将阴离子浓度从 1000 降低至 <0.1ppm。该研究于2018年发表在高影响力期刊Angewandte Chemie上，目前正在申请专利保护。这种去除可以在极端环境、高酸性溶液和高离子强度下进行，从而在溶液中或作为结晶沉淀物产生稳定的阴离子封装。这对于待玻璃化的液体高放废物来说是​​有利的，因为阴离子将在高放射性液体中稳定。我们的研究愿景是使用基于阴离子电荷和形态的穴状配体笼通过固定来实现受控去除。因此，我们需要确定控制封装和沉淀的因素：穴状配体的性质（其设计的变化如何反映在封装中）、复杂笼的金属中心、液体介质的条件（pH、离子强度）以及释放动力学。为了定义这种复杂的关系，我们将采用多学科方法，将计算筛选、实验合成和表征的力量结合在一起。这将加速可持续且具有成本效益的封装策略的开发，减少对环境的影响并提高废物形式的性能。我们的目标是支持我们的假设并实现以下目标：（1）基于先前报道的配体合成配体，但调节供体原子的性质和空腔的尺寸，用一系列金属中心来确定控制阴离子选择性的因素； (2) 确定笼和阴离子之间的相互作用以延迟动力学释放； (3) 利用综合实验和建模生成目标结构的原子模型，并表征其稳定性、形态和成分。