兰州大学机构库 >核科学与技术学院
新型冠醚配体和固相萃取树脂的合成及其对99Tc和241Am的提取研究
Alternative TitleSYNTHESIS OF NOVEL CROWN ETHER LIGANDS AND SOLID PHASE EXTRACTION RESINS FOR THE EXTRACTION OF 99Tc AND 241Am
邰文雅
Subtype博士
Thesis Advisor侯小琳
2023-08-31
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学博士
Degree Discipline放射化学
Keyword配体/固相萃取树脂,萃取/吸附,99Tc/241Am,放射性废水 ligand/solid phase extraction resin extraction/adsorption 99Tc/241Am radioactive wastewater
Abstract

核能的快速发展不可避免的产生一定的放射性废水,其中含有大量的超铀核素以及长寿命的裂变产物,如何安全处理放射性废水备受关注。在放射性废水中99Tc和241Am是两种值得关注的放射性核素。241Am是重要的超铀核素之一,其半衰期较长(T1/2 = 432.2年),具有高生物毒性,并且具有较好的经济价值,可用于制造烟雾报警器和中子源等。99Tc是一种长半衰期(T1/2 = 2.11 × 105年)β放射性核素,常以阴离子形式存在,具有较强的迁移性,其应用价值较高,可用于制备药物和β源等。因此,从放射性废水的安全处理和回收高价值放射性核素的角度出发,提取放射性废水中的99Tc和241Am具有重要的意义,不仅可以有效降低放射性废水的放射性水平,并且能变“废”为宝,对推动核能的可持续发展具有重要意义。

针对99Tc和241Am的提取,常用的分离方法包含吸附法、沉淀法、色谱法以及溶剂萃取法。色谱法因其高效高选择性等优点在众多分离方法中脱颖而出。该方法主要依托固相萃取树脂实现分离,然而现有的固相萃取树脂往往难以满足实际应用需求,如商业树脂售价昂贵或选择性较差,无法大量使用在放射性废水的处理过程中,而报道的一些固相萃取树脂大多分离性能有限、制备工艺复杂、生产成高,在工业应用中受限。因此,急需研发出一种高选择性、低成本及高稳定性的新型固相萃取树脂,实现放射性废水中99Tc和241Am的高效、高选择性提取。

本论文从配体的设计出发,以二苯并18-冠-6醚为中心桥联两种二甘醇酰胺(DGA)类官能团,通过偶联法合成出两种新型配体,分别为双(N,N-二丁基二甘醇酰胺)二苯并-18-冠-6醚(BisDBDGA-DB18C6)和双(N,N-二己基二甘醇酰胺)二苯并-18-冠-6醚(BisDHDGA-DB18C6)。选用Re(VII)和Eu(III)分别作为Tc(VII)和Am(III)的类似物,通过液液萃取实验探究其对Tc(VII)和Am(III)的萃取性能。并以XAD-1180N为基体,以上述合成的两种配体为特效官能团,制备了两种新型固相萃取树脂,系统研究其对Tc(VII)和Am(III)的吸附行为,具体研究结果如下:

1. 两种配体均可以快速(45秒以内)萃取酸性介质中的Re(VII)/Tc(VII),其中BisDHDGA-DB18C6的选择性更好(SFRe/Mo = 1.03´105),萃取容量更大(291 mmol Re(VII) / mol 配体)。通过红外、核磁滴定、质谱分析以及DFT计算推断萃取机理为配体中的冠醚、苯环以及酰胺与Re(VII)的强相互作用。在碱性介质中,两种配体对Re(VII)/Tc(VII)也具有较好的萃取效果,萃取动力学较快,在30秒内均可达到萃取平衡,其中BisDHDGA-DB18C6的萃取性能更好,其选择性更高(SFRe/Mo = 2.26 ´ 105),萃取容量更大(342 mmol Re(VII) / mol 配体)。通过FT-IR、核磁滴定、质谱分析等表征推断其萃取机理为配体中的冠醚和DGA通过形成离子对实现对Re(VII)分离。

2. 两种树脂对酸性介质中的Re(VII)/Tc(VII)均表现出良好的分离效果,吸附动力学快,在1 min内即可达到吸附平衡。其中,BisDHDGA-DB18C6/XAD-1180N对Re(VII)的吸附效果更优(Kd = 9.83 ´ 106 mL/g)、选择性更高(SFRe/Mo = 9.92 ´ 104,SFRe/Ru = 2435),受共存阴离子(Cl-、NO3-、SO42-、PO43-和ClO4-)的影响更小。两种树脂都具有较好的热稳定性、辐照稳定性以及酸碱稳定性。通过SEM、Mapping-EDS、FT-IR和XPS等表征分析,推断这两种树脂对Re(VII)的吸附机理为分子间强相互作用。在碱性介质中,两种树脂对Re(VII)/Tc(VII)同样具有较好的吸附效果。其中,BisDHDGA-DB18C6/XAD-1180N对Re(VII)的吸附效果更好(Kd = 2026 mL/g)、选择性更高(SFRe/Mo = 6.56 ´ 104),受共存阴离子(Cl-、NO3-、SO42-和PO43-)的干扰更小。此外,树脂还具有较好的辐照稳定性和热稳定性。结合SEM、Mapping-EDS、FT-IR和XPS等表征分析,推断树脂对Re(VII)的吸附机理为树脂中的特效官能团BisDHDGA-DB18C6或BisDHDGA-DB18C6与Na+先形成阳离子络合物,然后结合溶液中的Re(VII)形成离子对络合物。

3. 两种配体在硝酸介质中对Eu(III)/Am(III)均表现出较好的萃取效果。其中,BisDHDGA-DB18C6对Eu(III)的萃取能力更强,DEu为1.91´105;萃取容量较为可观,最大萃取容量为750 mmol Eu(III) / mol 配体;选择性更佳,SFEu/U = 7.50´104,SFEu/Th = 4.92 ´ 103。通过实验探究,推断配体对Eu(III)的萃取机理为阳离子交换。该配体会与[C2min]+以2:1配位比形成阳离子络合物,然后与Eu(III)进行交换,结合NTf2-形成中性络合物。此外,BisDHDGA-DB18C6和BisDBDGA-DB18C6还具有较好的重复利用性。

4. 两种树脂在高浓度硝酸介质中对Eu(III)/Am(III)表现出较好的吸附能力。在硝酸浓度为8 mol/L时,BisDHDGA-DB18C6/XAD-1180N树脂对Eu(III)的分离效果更佳,Kd = 1.20 ´ 105 mL/g;选择性更好,可以在23种离子共存的溶液中高选择性分离Eu(III)。通过SEM、Mapping-EDS、FT-IR和XPS等表征分析,推断树脂的吸附机理为树脂的特效官能团BisDHDGA-DB18C6或BisDHDGA-DB18C6的-C-O-C-和-C=O键与Eu(III)发生了配位作用,并结合溶液中的NO3-形成络合物。此外,两种树脂还具有较好的酸碱稳定性、辐照稳定性、热稳定性和重复利用性,可用于强辐照、高温及强酸环境中Eu(III)的分离。

Other Abstract

The rapid development of nuclear energy inevitably produces radioactive wastewater, which contains a large number of transuranic nuclides and long-lived fission products. Consequently, the safe treatment of radioactive wastewater has garnered significant attention. The radionuclides 99Tc and 241Am deserve attention in the context of radioactive wastewater. 241Am is one of the important transuranic nuclides with a long half-life (T1/2 = 432.2 years), high biological toxicity, and good economic value, which can be used to manufacture smoke alarms and neutron sources. On the other hand,99Tc is a β radionuclide with a long half-life (T1/2 = 2.11 × 105 years). It commonly exists in the form of anions and exhibits strong migratory behavior, rendering it highly valuable for applications such as drug preparation and β-source production. Therefore, the extraction of 99Tc and 241Am in radioactive wastewater holds significant importance from the perspective of safe treatment and high-value radionuclide recovery. This approach not only effectively reduces the radioactivity level of wastewater but also facilitates waste transformation into valuable resources, thereby promoting the sustainable development of nuclear energy.

For the extraction of 99Tc and 241Am, the common separation methods include adsorption, precipitation, chromatography and solvent extraction. The technique of chromatography distinguishes itself from other separation methods due to its exceptional efficiency and selectivity. This technique primarily relies on solid phase extraction resin for achieving separation, however, existing resins often fail to meet practical application requirements due to their high cost or limited selectivity. Consequently, they cannot be widely employed in treating radioactive wastewater. Additionally, some reported solid phase extraction resins have limitations in terms of separation performance, complex preparation processes, high production costs and restricted industrial applications. Therefore, there is urgent to develop a new solid phase extraction resin that exhibits high selectivity while being cost-effective and stable enough to enable efficient and highly selective separation of 99Tc and 241Am in radioactive wastewater.

In this study, based on the design of ligands, two diglycolamide-based (DGA) functional groups were brided with dibenzo 18-crown-6 ether as the center moiety. Two novel bis(N,N-dibutyldiglycolamide)dibenzo-18-crown-6 ether (BisDBDGA-DB18C6) and bis(N,N-dihexanediglycolamide)dibenzo-18-crown-6 ether (BisDHDGA-DB18C6) ligands have been synthesized by coupling method. Re(VII) and Eu(III) were selected as analogues for Tc(VII) and Am(III), respectively. And their extraction properties for Tc(VII) and Am(III) were investigated by liquid-liquid extraction experiments. Additionally, two novel solid phase extraction resins were synthesized by incorporating the XAD-1180N matrix with the developed ligands as specific functional groups, respectively. The adsorption behaviors of Tc(VII) and Am(III) were systematically studied. The specific research results are as follows:

1. Both ligands were able to extract Re(VII)/Tc(VII) in acidic media rapidly (within 45 s), with BisDHDGA-DB18C6 showing better selectivity (SFRe/Mo = 1.03 ´ 105) and higher extraction capacity (291 mmol Re(VII) / mol ligand). The extraction mechanism was deduced from FT-IR, NMR titration, mass spectrometry analysis and DFT calculations to be the strong interaction of crown ethers, benzene rings and amides in the ligands with Re(VII). In alkaline medium, the two ligands also showed better extraction of Re(VII)/Tc(VII) with faster extraction kinetics, reaching the extraction equilibrium within 30 s. Among them, the extraction performance of BisDHDGA-DB18C6 was better, with a higher selectivity (SFRe/Mo = 2.26 ´ 105) and a larger extraction capacity (342 mmol Re(VII) / mol ligand). The extraction mechanism was deduced from the characterisation by FT-IR, NMR titration and mass spectrometry analysis that the crown ether and DGA in the ligand achieved the separation of Re(VII) through the formation of ion-pair.

2. Both resins showed good separation of Re(VII)/Tc(VII) in acidic media with fast adsorption kinetics, reaching adsorption equilibrium within 1 min. Among them, BisDHDGA-DB18C6/XAD-1180N showed better adsorption (Kd = 9.83 ´ 106 mL/g) and higher selectivity (SFRe/Mo = 9.92 ´ 104, SFRe/Ru = 2435) for Re(VII), which was subjected to the coexisting anions ( Cl-, NO3-, SO42-, PO43- and ClO4-). Both resins had better thermal and irradiation stability as well as acid-base stability. The mechanism of adsorption and separation of Re(VII) by these two resins was deduced to be strong intermolecular interactions by characterisation analyses such as SEM, Mapping-EDS, FT-IR and XPS. The two resins also showed good adsorption effect on Re(VII)/Tc(VII) in alkaline medium. Among them, BisDHDGA-DB18C6/XAD-1180N showed better adsorption efficiency (Kd = 2026 mL/g) and higher selectivity (SFRe/Mo = 6.56 ´ 104) of Re(VII) with less interference from co-existing anions (Cl-, NO3-, SO42- and PO43-). In addition, the resin has better irradiation stability and thermal stability. Based on the SEM, Mapping-EDS, FT-IR and XPS characterisation analyses, it can be inferred that the adsorption mechanism of the resin onto Re(VII) involves the special effect functional group BisDHDGA-DB18C6 or BisDHDGA-DB18C6 in the resin forming a cationic complex with Na+ initially, followed by combining with Re(VII) in solution to form an ion-pair complex.

3. Both ligands were more effective in the extraction of Eu(III)/Am(III) in nitric acid medium. Among them, BisDHDGA-DB18C6 exhibited superior extraction efficiency towards Eu(III), with a DEu value of 1.91 ´ 105. It demonstrated significantly higher extraction capacity, reaching a maximum of 750 mmol Eu(III) / mol ligand and its selectivity was enhanced, as indicated by SFEu/U = 7.50 ´ 104, SFEu/Th = 4.92 ´ 103. The extraction mechanism of Eu(III) by the ligand was inferred to be a cation-exchange mechanism by experimental investigation. Initially, the ligand formed a 2:1 complex with [C2min]+, which subsequently underwent exchange with Eu(III) in the aqueous phase while binding NTf2- to form a neutral complex. In addition, BisDHDGA-DB18C6 and BisDBDGA-DB18C6 have better reusability.

4. The two resins exhibited better adsorption performance for Eu(III)/Am(III) in high concentration of nitric acid medium. The separation effect of BisDHDGA-DB18C6/XAD-1180N resin on Eu(III) was better when the concentration of nitric acid was 8 mol/L, Kd = 1.20 ´ 105 mL/g. The selectivity was significantly enhanced, enabling the highly selective separation of Eu(III) from a solution containing 23 co-existing elements. Through SEM, Map-EDS, FT-IR and XPS characterization, it was concluded that the adsorption mechanism of resin was that the specific functional group BisDHDGA-DB18C6 or BisDHDGA-DB18C6 had coordination with Eu(III) and combined with NO3- in solution to form a complex. In addition, the two resins have good reusability, acid-base stability, irradiation stability, and thermal stability, and can be used for the separation of Eu(III) in strong irradiation and high-temperature environments.

MOST Discipline Catalogue理学 - 化学
URL查看原文
Language中文
Other Code262010_120190902540
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/538002
Collection核科学与技术学院
Affiliation
兰州大学核科学与技术学院
Recommended Citation
GB/T 7714
邰文雅. 新型冠醚配体和固相萃取树脂的合成及其对99Tc和241Am的提取研究[D]. 兰州. 兰州大学,2023.
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