【作者】 王帅；

【导师】 钟宏；

【作者基本信息】 中南大学 ， 化学工艺， 2008， 博士

【摘要】 基于贵金属离子与配位体的量子化学计算及成键特性研究，设计并研制出一种新型的螯合树脂——聚酯基硫脲树脂，系统地研究了聚酯基硫脲树脂的合成及其对Au³⁺、Ag⁺、Pt⁴⁺、Pd²⁺等贵金属离子的吸附分离性能。应用密度泛函方法，用Gaussian 03软件在B3LYP／6-31G（d）水平上对常见配位体进行了量子化学计算，并运用Pearson软硬酸碱理论，研究了贵金属离子与配位体的成键特性，结果表明，酯基硫脲具有能量较高的σ型HOMO和能量较低的兀型LUMO，对金等贵金属离子具有优良的配位能力。理论分析与实验结果证实，含有酯基硫脲基团的高分子树脂——聚酯基硫脲树脂对贵金属离子具有优良的吸附能力和吸附选择性。采用逆向合成法，设计出了采用双异硫氰酸酯与多元胺加成聚合的聚酯基硫脲树脂合成路线，发明了一种聚酯基硫脲树脂的制备方法。以二元醇与三光气为原料，在N,N-二甲基苯胺（DMA）的催化下制备双氯甲酸酯；再将双氯甲酸酯与KSCN在DMA的催化下进行固-液相转移催化反应，制备出双异硫氰酸酯中间体；然后将双异硫氰酸酯与多元胺进行聚加成反应，制备出聚酯基硫脲树脂。通过双氯甲酸酯、双异硫氰酸酯以及聚酯基硫脲树脂合成工艺条件的系统实验研究，得到了聚酯基硫脲树脂合成的优化工艺条件与制备方法：制备双氯甲酸酯时三光气和DMA与二元醇摩尔比分别为2．2：3和0．035：1，反应温度为5℃，反应时间为10 h；制备双异硫氰酸酯时双氯甲酸酯与KSCN摩尔比为1：2．5，反应温度为5℃，反应时间为3．5 h；聚合反应时氨基与异硫氰酸酯基摩尔比为1．25：1，反应温度为5℃，反应时间为5 h。制备出聚乙基酯基硫脲树脂（PE）、聚丁基酯基硫脲树脂（PB）、聚乙二醚基酯基硫脲树脂（PD）、聚己基酯基硫脲树脂（PH）和聚二乙氧基乙基酯基硫脲树脂（PT）5个系列共20种树脂，其中PB和PD系列树脂基于二元醇的收率较高，均在90％以上。采用元素分析、FTIR、XRD、SEM、TG等对树脂进行了结构和性能表征。系统地研究了聚酯基硫脲树脂对Au³⁺、Ag⁺、pt⁴⁺、pd²⁺4种贵金属离子的吸附性能。采用静态吸附法考察了聚酯基硫脲树脂种类和聚合单体比例对树脂吸附Au³⁺性能的影响，建立了树脂结构与吸附性能的关系，筛选出PB和PD树脂进行进一步的研究。考察了PB和PD树脂对贵金属离子的静态吸附性能，结果表明，树脂对Au³⁺、Ag⁺、Pt⁴⁺、Pd²⁺具有较高的吸附容量，其中PB1对4种金属离子的吸附容量分别为4．55、4．32、1．60和3．00 mmol·g^-1，PD1的吸附容量分别为4．90、4．50、1．85和3．41 mmol·g^-1。PB1和PD1对Au³⁺、Ag⁺、Pt⁴⁺、Pd²⁺的吸附容量随吸附时间和贵金属离子初始浓度的增加而增加；对Au³⁺、Pt⁴⁺的吸附容量随酸度的增加而略有增加，对Pd²⁺的吸附容量基本不变，对Ag⁺的吸附容量随酸度的增加先增加后减小。动态吸附实验表明，树脂对Au³⁺和Ag⁺的吸附率随流速的增加而下降，随树脂用量的增加而增大。测定了树脂对Au³⁺和Ag⁺的穿透曲线，达到穿透状态时，树脂吸附率较高。通过对吸附实验数据和树脂吸附前后的FTIR和XPS分析，揭示了树脂吸附贵金属离子的动力学、热力学和配位机理。PB1和PD1树脂对贵金属离子的吸附数据符合Boyd液膜扩散方程，吸附过程属于液膜扩散控制过程。吸附过程符合Langmuir吸附等温式和Freundlich吸附等温式，且更符合前者，吸附过程为单分子层吸附；采用热力学公式计算吸附过程的△H、△G和AS。FTIR和XPS分析表明，PB1和PD1树脂吸附贵金属离子过程中，树脂配位体与贵金属离子发生了配位反应，树脂吸附Au³⁺和Ag⁺时，S、N、O向Au和Ag提供电子；树脂吸附Pt⁴⁺和Pd²⁺时，S、O向Pt和Pd提供电子。考察了树脂对贵金属离子的分离性能，建立了树脂吸附贵金属离子后的再生工艺。树脂对贵金属离子具有较高的吸附容量，对Cu²⁺、Zn²⁺、Fe³⁺、Co²⁺、Ni²⁺、Pb²⁺吸附较少，而对Ca²⁺、Mg²⁺、Na⁺、K⁺基本不吸附。在二元金属离子混合溶液中，PB1和PD1树脂对Au³⁺、Ag⁺、Pt⁴⁺、Pd²⁺的分离因子分别大于1300、110、90和80，说明树脂对贵金属离子具有优良的吸附选择性。在动态吸附实验中，PB1和PD1树脂对混合溶液中Au³⁺和Ag⁺仍具有较高的吸附率，说明将树脂应用于贵金属和贱金属的分离具有较高的可行性。采用酸性硫脲溶液洗脱PB1和PD1树脂上吸附的贵金属离子，树脂的洗脱性能和重复利用性能良好。制备了一种新型的活性炭纤维布和PET无纺布支撑聚酯基硫脲树脂复合吸附材料，并研究了复合吸附材料对Au³⁺的吸附性能。采用浸渍法使双异硫氰酸乙二醚基酯与二乙烯三胺在ACFC或PET无纺布上聚合，制备出新型的聚酯基硫脲树脂复合吸附材料ACFC-PD1和PET-PD1，并采用FTIR、SEM、元素分析和TG等对它们进行了表征。采用静态吸附法考察了ACFC-PD1和PET-PD1对Au³⁺的吸附，吸附数据符合Boyd液膜扩散方程、Langmuir吸附等温式和Fredulich吸附等温式。吸附容量随温度的增加而增大，吸附过程为吸热过程。复合吸附材料改善了树脂的物理性能和吸附性能，具有一定的应用前景。更多还原

【Abstract】 Based on the quantum chemistry calculation and bonding features of noble metal ions and its ligands, a new chelating resin, polymeric ester thiurea resin, was designed and synthesized and applied to adsorption and separation for Au³⁺, Ag⁺, Pt⁴⁺ and Pd²⁺.Quantum chemistry calculation of common ligands was performed in the framework of density functional theory with Gaussian 03 software at B3LYP/6-31G（d） level, and bonding features of noble metal ions and ligands were studied with the help of hard and soft acids and bases theory. The result indicates that the energy ofσ-type HOMO of ester thiourea group is very high, that ofπ-type LUMO is low relatively and is negative, so it has strong strong coordinating ability with noble metal ions. According to theoretical analysis and experimental results, polymeric ester thiurea resins have good adsorption ability and selectivity to noble metal ions.Reverse synthesis method was employed to design the synthesis route of polymeric ester thiourea resin and their intermediates, and a novel polymeric ester thiourea resin was invented. Bischloroformates were prepared by the reaction of diols and triphosgene, catalyzed by N,N-dimethyl aniline （DMA）; bischloroformates reacted with KSCN by solid-liquid phase transfer catalysis, also catalyzed by DMA, from which diisothiocyanatidates were synthesized; at last, diisothiocyanatidates reacted with polyamine to obtain polymeric ester thiourea resins. Synthesis technologies of bischloroformates, diisothiocyanatidates and polymeric ester thiourea resins were studies systematically by experimental research, and optimal conditions were as follows: molar ratio of triphosgene to doils 2.2:3, molar ratio of DMA to doils 0.035:1, reaction temperature 5℃, and reaction time 10 h for preparation of bischloroformates; molar ratio of bischloroformates to KSCN 1:2.5, reaction temperature 5℃, and reaction time 3.5 h for preparation of diisothiocyanatidates; molar ratio of amino groups and isothiocyanatidate groups 1.25:1, reaction temperature 5℃, and reaction time 5 h for polymerization reactions. Five series and 20 kinds of polymeric ester thiourea resins, polymaric ethyl ester thiurea resins （PE）, polymaric butyl ester thiurea resins （PB）, polymaric diethyl ether ester thiurea resins （PD）, polymaric hexyl ester thiurea resins （PH）, polymaric diethoxyethane ester thiurea resins （PT）, were prepared. Yields of PB and PD are all above 90%, and higher than others. Element analysis, FTIR, XRD, SEM and TG, etc. were adopted to characterize their structures and properties.Adsorption properities of polymeric ester thiurea resins for Au³⁺, Ag⁺, Pt⁴⁺ and Pd²⁺, etc. were investigated systematically. The relationship of structure of resins and adsorption properities were studied by batch test, and according to effects of the kind of resins and molar ratios of monomers on adsorption capacities for Au³⁺, PB and PD were selected for farther studies. PB and PD have higher adsorption capacities for Au³⁺, Ag⁺, Pt⁴⁺ and Pd²⁺, for example, adsorption capacities of PB1 for Au³⁺, Ag⁺, Pt⁴⁺ and Pd²⁺ are 4.55, 4.32, 1.60 and 3.00 mmol·g^-1 respectively, and those of PD1 are 4.90, 4.50, 1.85 and 3.41 mmol·g^-1 respectively. Adsorption capacities of PB1 and PD1 for Au³⁺, Ag⁺, Pt⁴⁺ and Pd²⁺ increase with the increases of adsorption time and initial concentrations of nobel metal ions; With the increases of acidities, adsorption capacities increase for Au³⁺ and Pt⁴⁺, keep invariant for Pd²⁺, increase firstly and decrease successively for Ag⁺. In dynamic adsorption experiments for Au³⁺ and Ag⁺, adsorption rates of PB1 and PD1 decrease with the increase of flow rates and increase with the increase of the amounts of resins. Breakthrough curves were also determined, and the adsorption rates are high at penetrative points.Adsorption kinetics, thermodynamics and coordination mechanism of resins were revealed by analyzing adsorption data and FTIR and XPS data of resins fore-and-aft adsorption. The adsorption data of PB and PD fit Boyd’s diffusion equation of liquid film, indicating the adsorption is controlled by liquid film diffusion. The isothermal adsorption of PB 1 and PD1 obey Langmuir and Freundlich equation, especially the former equation, indicating that the adsorption is a monolayer one;△H,△G and△S were calculated by thermodynamic formulas. According to FTIR and XPS, functional groups of the resins coordinated with noble metal ions in the adsorption. S, N and O atoms donate electrons to Au and Ag atoms in the adsorption of Au³⁺ and Ag⁺; S and O atoms donate electrons to Pt and Pd atoms in the adsorption of Pt⁴⁺ and Pd²⁺.Separation properities and regeneration technology of polymeric ester thiurea resins for noble metal ions were studied. PB and PD have higher adsorption capacities for noble metal ions, those for Cu²⁺, Zn²⁺, Fe³⁺, Co²⁺, Ni²⁺ and Pb²⁺ are lower relatively, and those for Ca²⁺, Mg²⁺, Na⁺ and K⁺ are the lowest. Separation factors of noble-base metals binary metal ion systems are above 1300, 110, 90 and 80 for Au³⁺, Ag⁺, Pt（4+） and Pd²⁺ respectively, indicating that adsorption selectivity for noble metal ions is excellent. In dynamic adsorption experiments, adsorption capacities of Au³⁺ and Ag⁺ in mixing solutions are still very high, so it can be concluded that the resins could be applied to separation of noble and base metal ions. Acidic thiourea solutions were applied to desorption of noble metals on PB1 and PD1, and the results indicate that elution and regeneration properties are very good.Active carbon fiber cloth （ACFC） and polyethylene terephthalate （PET） nonwoven cloth support polymeric ester thiurea resin composite absorbents were prepared, and their adsorption properities were also investigated. Polymeric ester thiurea resin composite absorbents, ACFC-PD1 and PET-PD1, were prepared by impregnation, polymerizing diethyl ether diisothiocyanate and diethylene triamine on ACFC and PET nonwoven cloth. They were characterized by FTIR, SEM, element analysis and TG, etc. Batch testes were adopted to investigate adsorption property of composite absorbents for Au³⁺. The adsorption data fit Boyd’s diffusion equation of liquid film, Langmuir and Freundlich isotherm equation. Adsorption capacities decrease with the increases of temperatures, indicating that the adsorption is an exothermic process. The physical and adsorption properities of absorbents are improved by modification, and the composite absorbents are hopeful to be put into practice.更多还原