离子液体用于纤维素溶解、放射性碘捕集及可蒸馏离子液体的机理研究
发布时间：2019-06-21 20:37
【摘要】：离子液体作为绿色溶剂具有众多优良特性,近年来得到广泛研究。研究离子液体独特的性质对于挖掘其潜在应用前景具有深远意义。本论文使用理论计算和实验方法研究了离子液体溶解纤维素、离子液体捕集和存储放射性碘和离子液体的可逆性、蒸馏性。本论文的主要研究内容和研究结论:1、使用纤维二糖作为模型利用理论计算和实验方法研究醋酸根离子液体溶解纤维素的机理。静电势能分布及结构分析对复合物结构特征进行了解析。多种波函数分析方法,包括分子中原子理论(AIM)、约化密度梯度(RDG)、自然键轨道理论(NBO)等,都表明纤维二糖与离子液体的相互作用(包括氢键相互作用和范德华相互作用)强度与溶解度有关。实验表明升高温度能显著提高纤维素在[Bmim][OAc]中的溶解度。NMR表明纤维素与离子液体形成分子间氢键以及内部固有的氢键断裂使得纤维素能够溶解于离子液体中。2、使用理论计算方法研究了1-丁基-3-甲基咪唑类离子液体捕集放射性碘的机理。结构的设计及优化参考了静电势能在分子表面的分布。相互作用能表明了复合物中放射性碘与离子液体、阴离子形成的卤键强度。为了进一步揭示离子液体捕获放射性碘的机制,采用了电荷分布和振动频率分析探索原子电荷密度和振动频率的变化。使用自然键轨道理论(NBO)和分子中原子理论(AIM)表征了体系中的卤键。实验和计算结果都表明放射性碘能被离子液体以1:1摩尔比捕获。[Bmim][Br],[Bmim][I]和[Bmim][Cl]在5小时内对碘的捕获效率高达80%,表现出较好的捕获效率和应用潜力。3、利用理论计算和实验方法研究了十六种基于N-C=X(N,O and S)设计的可逆性的离子液体。静电势能分析表明N-C=X上X原子的高亲核活性使得甲基转移更容易实现。能量计算结果揭示了各离子液体的合成及其对应的逆向反应实现的难易程度。实验上合成了七种离子液体并通过热重实验考察了其热稳定性。结果表明N-C=O类离子液体的初始分解温度在250℃左右,故该离子液体的逆反应在该温度下易于实现。270℃温度下[MMU][Tf O]的失重在6小时后小于20%表明其具高的热稳定性。键级分析、分子中原子理论(AIM)、约化密度梯度(RDG)和自然键轨道理论(NBO)等波函数分析方法表明非共价相互作用是实现甲基转移的驱动力。
[Abstract]:As a green solvent, ionic liquids have many excellent properties, which have been widely studied in recent years. It is of great significance to study the unique properties of ionic liquids for exploring their potential application prospects. In this paper, the reversibility and distillation of ionic liquid dissolved cellulose, ionic liquid trapping and storage of radioactive iodine and ionic liquid have been studied by theoretical calculation and experimental method. The main research contents and conclusions of this paper are as follows: 1. Using cellulose disaccharide as a model, the mechanism of cellulose dissolution by acetate ion liquid was studied by theoretical calculation and experimental method. The distribution and structure analysis of electrostatic potential energy were carried out to analyze the structural characteristics of the composite. A variety of wave function analysis methods, including (AIM), reduced density gradient (RDG), natural bond orbital theory (NBO), show that the strength of the interaction between cellulose disaccharide and ionic liquids (including hydrogen bond interaction and van der Waals interaction) is related to solubility. The experimental results show that the solubility of cellulose in [Bmim] [OAc] can be significantly improved by increasing the temperature. NMR shows that cellulose and ionic liquid form intermolecular hydrogen bond and internal inherent hydrogen bond fracture so that cellulose can dissolve in ionic liquid. 2. The mechanism of trapping radioactive iodine by 1-butyl3-methylimidazole ionic liquid has been studied by theoretical calculation method. The design and optimization of the structure refer to the distribution of electrostatic potential energy on the molecular surface. The interaction between radioactive iodine and anions in the complex shows the strength of halogen bonds formed by anions. In order to further reveal the mechanism of radioactive iodine capture by ionic liquids, charge distribution and vibration frequency analysis were used to explore the changes of atomic charge density and vibration frequency. The halogen bonds in the system were characterized by natural bond orbital theory (NBO) and molecular atomic theory (AIM). The experimental and calculated results show that radioactive iodine can be captured by ionic liquids at 1:1 molar ratio. [Bmim] [Br], [Bmim] [I] and [Bmim] [Cl] have high capture efficiency and application potential within 5 hours, showing good capture efficiency and application potential. 3. Sixteen kinds of reversible ionic liquids based on N-C=X (N, O and S) were studied by theoretical calculation and experimental method. Electrostatic potential energy analysis shows that the high nucleophilic activity of X atom on N-C=X makes methyl transfer easier. The results of energy calculation reveal the difficulty of the synthesis of each ionic liquid and its corresponding reverse reaction. Seven kinds of ionic liquids were synthesized and their thermal stability was investigated by thermogravimetric test. The results show that the initial decomposition temperature of N-C=O ionic liquid is about 250 鈩，
本文编号：2504333
[Abstract]:As a green solvent, ionic liquids have many excellent properties, which have been widely studied in recent years. It is of great significance to study the unique properties of ionic liquids for exploring their potential application prospects. In this paper, the reversibility and distillation of ionic liquid dissolved cellulose, ionic liquid trapping and storage of radioactive iodine and ionic liquid have been studied by theoretical calculation and experimental method. The main research contents and conclusions of this paper are as follows: 1. Using cellulose disaccharide as a model, the mechanism of cellulose dissolution by acetate ion liquid was studied by theoretical calculation and experimental method. The distribution and structure analysis of electrostatic potential energy were carried out to analyze the structural characteristics of the composite. A variety of wave function analysis methods, including (AIM), reduced density gradient (RDG), natural bond orbital theory (NBO), show that the strength of the interaction between cellulose disaccharide and ionic liquids (including hydrogen bond interaction and van der Waals interaction) is related to solubility. The experimental results show that the solubility of cellulose in [Bmim] [OAc] can be significantly improved by increasing the temperature. NMR shows that cellulose and ionic liquid form intermolecular hydrogen bond and internal inherent hydrogen bond fracture so that cellulose can dissolve in ionic liquid. 2. The mechanism of trapping radioactive iodine by 1-butyl3-methylimidazole ionic liquid has been studied by theoretical calculation method. The design and optimization of the structure refer to the distribution of electrostatic potential energy on the molecular surface. The interaction between radioactive iodine and anions in the complex shows the strength of halogen bonds formed by anions. In order to further reveal the mechanism of radioactive iodine capture by ionic liquids, charge distribution and vibration frequency analysis were used to explore the changes of atomic charge density and vibration frequency. The halogen bonds in the system were characterized by natural bond orbital theory (NBO) and molecular atomic theory (AIM). The experimental and calculated results show that radioactive iodine can be captured by ionic liquids at 1:1 molar ratio. [Bmim] [Br], [Bmim] [I] and [Bmim] [Cl] have high capture efficiency and application potential within 5 hours, showing good capture efficiency and application potential. 3. Sixteen kinds of reversible ionic liquids based on N-C=X (N, O and S) were studied by theoretical calculation and experimental method. Electrostatic potential energy analysis shows that the high nucleophilic activity of X atom on N-C=X makes methyl transfer easier. The results of energy calculation reveal the difficulty of the synthesis of each ionic liquid and its corresponding reverse reaction. Seven kinds of ionic liquids were synthesized and their thermal stability was investigated by thermogravimetric test. The results show that the initial decomposition temperature of N-C=O ionic liquid is about 250 鈩，
本文编号：2504333
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