两性离子对杂化膜的制备、结构调控及吸附脱除放射性核素机理研究

Nuclear electric power generation, which is regarded as one of the most promising new technologies for energy supply, has been paid great attention throughout the World. However, the crisis at the Fukushima nuclear plant has surprised the administrators. As a result, security for the treatment of radioactive waste from nuclear power plants has turned into a hot topic and worried the inhabitants. Currently, it is well accepted that membrane adsorption separation is one of the most effective methods to remove radionuclide from radioactive waste. Nevertheless, this technique also reveals such demerits as: low thermal stability and inefficient removing amount of radionuclide from radioactive waste when this type of membranes was used. Especially, the adsorptive mechanism of radionuclide from radioactive waste using membrane separation has not been better understood so far, its further application in various fields is thus highly blocked. Hopefully, these disadvantages occurred in current separation process can be well resolved if the following two dominating factors are considered, i.e. preparing new separation membrane and detecting the adsorptive mechanism of radionuclide from radioactive waste using membrane separation. For such purpose, herein, novel zwitterionic hybrid membranes will be prepared and used to remove radionuclide from radioactive waste via adsorption. which mainly focus on such three aspects as: (1) the well design of hybrid precursor, (2) the preparation of novel zwitterionic hybrid membranes, and (3) the better understing of adsorptive mechanism of radionuclide from radioactive waste. Many efforts will be made to increase both the thermal stability of the hybrid membranes used in this study and the adsorption amounts of radionuclide using zwitterionic hybrid membranes. Based on the results obtained, a theoretical mode will be established to correlate the relationship between the mode of hybrid precursor, membrane structure and the adsorption efficiency of radionuclide so as to explore the adsorptive mechanism for radionuclide removal from radioactive waste. It is expected that the adsorptive mechanism for radionuclide removal from radioactive waste using zwitterionic hybrid membrane can be disclosed and fruitful results for the treatment of radioactive waste can be achieved, demonstrating the novelty of this study proposed.

核能发电近年来获得迅猛发展，但日本福岛核泄露造成的放射性废水污染给核电发展敲响了警钟，如何处理放射性废水污染成为人们关注的焦点。膜吸附是治理放射性废水污染的理想方法之一。但目前存在膜稳定性差、放射性核素脱除效率不高等缺点，特别是对放射性核素脱除机理等科学问题缺乏研究，成为该技术推广应用的主要障碍，因此制备新型吸附膜，探讨放射性核素脱除机理是克服现有技术缺陷的关键。本项目拟选用两性离子对杂化膜吸附脱除放射性核素，对放射性废水污染等核电安全问题进行基础研究。内容包括：设计构建杂化前驱体基团新模式，制备两性离子对杂化膜，用该膜脱除废水模拟液中放射性核素；力求通过基团模式设计和结构调控来提高放射性核素吸附量，并建立理论模型，从理论上将基团构建新模式、膜结构形态和放射性核素脱除效率进行关联；探讨放射性核素脱除机理。本项目旨在揭示两性离子对杂化膜吸附脱除放射性核素机理，为放射性废水治理提供科学依据。

随着我国核电技术的迅猛发展以及核电站数量的逐步增加，核电安全已引起人们格外关注。日本福岛核电站泄漏事故给我们敲响了警钟，如何安全、经济和妥善地处理放射性废水已成为我国核电工业可持续发展中必须解决的重点问题之一。采用新技术、新方法处理核电废水就成为目前我国核电站建设中迫切需要解决的一大关键科技难题。离子交换杂化膜吸附是治理低浓度放射性废水污染的有效方法之一。本项目从杂化前驱体基团构建模式的设计入手，系统地进行了两性离子对杂化前驱体及杂化膜的设计、制备和表征研究等探索性工作，筛选出3种两性离子对杂化前驱体，制备了一系列两性离子对杂化膜，研究了其吸附脱除放射性废水模拟液中锶（Sr2+）、钴（Co2+）等金属离子的性能，取得了一些有影响、有重要应用价值的学术成果和关键实验数据。通过Lagergren准一级和二级动力学理论模型，Langmuir和 Freundlich等温线理论模型以及内扩散模型(Intraparticle diffusion)的数值拟合，探讨了杂化前驱体基团构建模式与Sr2+、Co2+离子脱除效率的关系，由此获得两性离子对杂化膜吸附脱除放射性废水模拟液中锶（Sr2+）、钴（Co2+）等金属离子的吸附机理。结果表明： Sr2+和Co2+离子在这些两性离子对杂化膜上的吸附均遵循Lagergren准二级动力学模型。吸附机理研究表明：Sr2+在杂化膜表面的吸附是扩散−化学吸附起主要作用，起始阶段膜内扩散是主要控制步骤；而Co2+离子在杂化膜表面的吸附不遵循化学吸附规律，内扩散不是主要的控制过程。热力学参数ΔS、ΔG和 ΔH计算表明：Sr2+和Co2+离子在这些杂化膜上的吸附是一个吸热过程，可以自发进行。这些关键实验数据的获得，为两性离子对杂化膜在放射性废水净化处理等方面的应用提供了理论依据，对拓展离子交换膜在核电废水处理领域的应用具有积极意义。