【作者】 苏红梅；

【导师】 杨延钊；

【作者基本信息】 山东大学 ， 有机化学， 2020， 硕士

【摘要】 基于资源短缺和环境污染日益严重的当今局势,低碳环保以及有限资源的高效回收利用成为人们关注的焦点。广泛的应用和有限的储量决定了金的萃取回收以及循环利用更加重要。液-液萃取因其具有操作简单,自动化和连续性等优势被广泛使用于金的回收中。但是,使用传统的有机溶剂萃取金存在高毒、低选择性等弊端,故此,离子液体作为一种绿色稳定的有机盐取代传统萃取剂是当前研究热点体系之一。而咪唑类离子液体相较于吡啶类、季膦类和季铵类离子液体,由于电荷具有较高离域性,故该类离子液体有高离子导电性和低粘度等特点。但对于与咪唑类离子液体相似的苯并咪唑类离子液体研究很少,而对于双子型苯并咪唑类离子液体的合成和萃取研究更少。鉴于此,我们探索了双子型苯并咪唑类离子液体的合成并将其应用于金的萃取,为开拓更加高效的功能化离子液体提供了理论基础。首先,我们对双子型苯并咪唑类离子液体的合成进行了系统地研究,具体合成了九种离子液体,分别为:N,N’-二烷基双子型苯并咪唑离子液体:[C4-6-C4BIm]Br2、[C8-6-CgBIm]Br2、[C4-4-C4BIm]Br2;质子类双子型苯并咪唑离子液体:[H-4-HBIm]Br2、[H-6-HBIm]Br2;Tf2N型双子型苯并咪唑离子液体:[C4-4-C4BIm](Tf2N)2、[C4-6-C4BIm](Tf2N)2、[H-4-HBIm](Tf2N)2、[H-6-HBIm](Tf2N)2。并使用核磁共振波谱和质谱等方法对合成的离子液体进行了表征。其次,对于新合成的双子型苯并咪唑类离子液体,为了研究其应用潜质,以金为目标金属,探索了其在萃取领域的应用价值。具体选取离子液体[C4-6-C4BIm]Br2,研究了其在盐酸介质中萃取金(Ⅲ)的性能,详细考察了萃取剂浓度、氯化钠浓度、溴化钠浓度以及初始金属离子浓度对萃取效率的影响,然后根据1H NMR、FT-IR和等摩尔变化法,研究了[C4-6-C4BIm]Br2萃取金(Ⅲ)的机理。同时从理论计算角度验证了机理。此外,还研究了 Au(Ⅲ)萃取的平衡、热力学和动力学模型,对预测和指导工业应用中的Au(Ⅲ)的萃取行为具有较高的参考价值。最后,我们还探索了该萃取剂对金萃取的选择性。结果表明,[C4-6-C4BIm]Br2是一种极其高效的萃取剂,少量的[C4-6-C4BIm]Br2就可以获得极好的萃取效率。另外,鉴于Tf2N型双子型苯并咪唑离子液体的疏水性能更好,我们选取其中一种离子液体[C4-4-C4BIm](Tf2N)2,对其在盐酸介质中萃取金的性能进行了研究,详细考察了萃取剂浓度、氯化钠浓度、盐酸浓度以及初始金属离子浓度对萃取效率的影响,然后根据FT-IR和等摩尔变化法,研究了[C4-4-C4BIm](Tf2N)2萃取金(Ⅲ)的机理。同时从理论计算角度验证了机理。结果发现,该类离子液体同样有优良的萃取性能,以及由于本身所具有的良好的稳定性和疏水性,在萃取领域将有广阔的应用前景。更多还原

【Abstract】 Based on the current situation of resource shortage and increasingly serious environmental pollution,low-carbon environmental protection and efficient recycling of limited resources have become the focus of attention.In view of its wide application and limited reserves,the recovery and recycling of gold become more important.Liquid-liquid extraction is widely used in gold recovery due to its advantages of simple operation,automation,and continuity.However,use of traditional organic solvents is limited by their high toxicity and low selectivity for gold.Therefore,use of ionic liquids as a green and stable organic salt to replace traditional extractants is one of the current research hotspots.Imidazole ionic liquids have higher ionic conductivity and lower viscosity than pyridine,quaternary phosphines and quaternary ammonium ionic liquids due to high charge delocalization.However,there are few studies on benzimidazolium ionic liquids similar to imidazole ionic liquids,and there are fewer studies on the synthesis and extraction of gemini-benzimidazolium ionic liquids.In view of this,we explored the synthesis of gemini-type benzimidazolium ionic liquids and applied them to gold extraction,providing a theoretical basis for developing more efficient functionalized ionic liquids.First,we systematically studied the synthesis of gemini-benzimidazolium ionic liquids.nine ionic liquids were synthesized:N,N’-dialkyl gemini-benzimidazolium ionic liquid:[C4-6-C4BIm]Br2,[C8-6-C8BIm]Br2,[C4-4-C4BIm]Br2;protic gemini-benzimidazolium ionic liquid:[H-4-HBIm]Br2,[H-6-HBIm]Br2;Tf2N gemini-benzimidazolium ionic liquid:[C4-4-C4BIm](Tf2N)2,[C4-6-C4BIm](Tf2N)2,[H-4-HBIm](Tf2N2),[H-6-HBIm](Tf2N)2.The synthetic ionic liquids were characterized by nuclear magnetic resonance spectroscopy and mass spectrometry.Then,for the gemini-type benzimidazolium ionic liquids,in order to study its application potential in the field of extraction,we used gold as the target metal and the ionic liquid[C4-6-C4BIm]Br2 to extract gold(Ⅲ)from hydrochloric acid medium.The effects of extractant concentration,sodium chloride concentration,sodium bromide concentration and initial metal ion concentration on the extraction efficiency were investigated in detail.The mechanism between[C4-6-C4BIm]Br2 and Au(Ⅲ)was proven by 1H NMR spectra FT-IR spectra and Job’s method.At the same time,quantum chemical calculations were carried out to evidence the mechanism theoretically.The equilibrium,thermodynamic and kinetic models of Au(Ⅲ)extraction were also studied,which has a high reference value for predicting and guiding the extraction behavior of Au(Ⅲ)in industrial applications.Finally,we also explored the selectivity of this extractant for gold extraction.The results show that[C4-6-C4BIm]Br2 is an efficient extractant,and a small amount of[C4-6-C4BIm]Br2 can obtain excellent extraction efficiency.In addition,in view of the better hydrophobic properties of Tf2N gemini-benzimidazole ionic liquids,we selected the ionic liquid[C4-4-C4BIm](Tf2N)2 to study its performance in extracting gold from hydrochloric acid medium.The effects of extractant concentration,sodium chloride concentration,hydrochloric acid concentration and initial metal ion concentration on extraction efficiency were investigated in detail.The mechanism of gold(Ⅲ)extraction was studied according to FT-IR and Job’s method.Furthermore,the mechanism is verified from the perspective of theoretical calculation.It was found that this type of ionic liquid also has excellent extraction performance,and due to its good stability and hydrophobicity,it will have broad application prospects in the extraction field.更多还原