【作者】 袁继文；

【导师】 王强；

【作者基本信息】 武汉纺织大学 ， 物理化学， 2011， 硕士

【摘要】 传统湿法冶金的溶剂萃取技术提取金属的过程其实质主要是金属阳离子和萃取剂中的质子交换,在溶剂萃取过程中未被萃取的阴离子以及大量有机溶剂的使用对环境造成污染,同时被金属离子置换出的氢离子亦易使萃取剂质子化而降低功效。为探索解决这些问题,本研究合成了三种新型的能同时结合金属盐阳离子和阴离子的Salen类席夫碱两性离子双位配体,并首次将其以共价键固定到硅胶载体上制备可循环再生的固体配位萃取剂。主要进行了以下几个方面的研究工作:1、合成三种新型水杨醛衍生物5-溴-3-亚甲基哌啶水杨醛、5-溴-3-亚甲基吗啡啉水杨醛和5-甲基-3-亚甲基哌啶水杨醛,并通过核磁共振表征了目标化合物。2、通过硅胶的氯硅烷功能化和对残余硅醇基团的封端,合成了化学修饰的硅胶以便负载席夫碱配体;通过红外光谱和元素分析表征经化学修饰后硅胶的结构。3、利用水杨醛衍生物和三亚乙基二胺反应合成了相应的三种席夫碱双位配体;利用席夫碱桥联基团上的肿胺基和硅胶上的烷基氯活性基团反应,成功将三种席夫碱以共价键结合到硅胶表面,从而制成硅胶负载的固体配位萃取剂D、E、F;通过元素分析确定硅胶上席夫碱双位配体的负载量。4、基于配体与金属盐反应结合金属离子的同时,酚羟基质子转移至邻位的叔胺基上形成质子化的正电荷环境,从而通过氢键和静电作用力与阴离子结合。因此该固体萃取剂可同时结合金属盐的阳,阴离子。通过利用原子吸收光谱和离子色谱等技术测试了三种固体配位萃取剂对金属盐（硫酸盐,硝酸盐和氯化物）阳、阴离子的配位萃取性能。实验结果表明萃取剂对Cu（Ⅱ）、Co（Ⅱ）、Ni（Ⅱ）和Fe（Ⅱ）的萃取率大于95%,而对Zn（Ⅱ）和Mn（Ⅱ）的萃取率则随金属盐不同分别介于62-96%和52-94%。而萃取剂对阴离子的萃取率则随金属盐的变化相差较大,并且比阳离子的萃取效果弱,其中对SO42?、NO₃^-及Cl^-的最大萃取率分别为:88%,64%和64%。5、初步分析了对阳离子和阴离子不同萃取效果及相随离子的影响,以期为优化配体设计及萃取条件,以及进一步探索影响阳、阴离子同时萃取效率的因素和机理提供借鉴。更多还原

【Abstract】 Metal ion recover via solvent extraction in hydrometallurgical process is essentially an ion-exchange process in which the desired metal cation exchanges with protons from an extractant. However, the anions of the metal salt are not extracted and they are hazardous to environment; large volume of organic solvents used during the solvent extraction process also causes environmental pollution. On the other hand, the efficiency of extractants is decreased due to protonation by H+ built up from the metal ion replacement. To explore solutions to these problems, we have synthesized three novel Salen-type Schiff base ditopic ligands, which can bind cation and anions of metal salt simultaneously due to the zwitterionic structure. The ditopic ligand have been grafted onto Silica gel via covalent bond, thus enabling recycle and reuse of the solid extractants.1. Three new salicylaldehyde derivatives, 5-bromo-3-methylene piperidine salicylaldehyde, 5-bromo-3-methylene morpholine, and 5-methyl-3-methylene piperidine salicylaldehyde have been synthesised and characterised by NMR.2. Chemical modification has been carried out for silica gel in order to introduce functional groups of alkyl chloride and cap the residual silnol groups. The surface characteristic of chemically modified silica gel was analysed according to infrared spectroscopy and elemental analysis.3. Three Schiff base ligands were synthesised via the reaction between salicylaldehydes and diethylenetriamine; silical gel supported solid extractants D,E and F were prepared by covalently linking Schiff-base ligands to silica gel surface via the reaction between -NH- in the bridging of Schiff bases and alkyl-Cl group from the silica gel; the amount of Schiff base ligands grafted onto silica gel surface was analysised according to elemental analysis results.4. Upon coordination of the Schiff base with metal ions, protons from phenolic OH transfer to the neighbouring tertiary amino group forming a positively charged environment, which facilitates the binding of anions through hydrogen bonding and electrostatic interactions. The zwitterionic nature of the ligand makes it possible to bind cation and anion（s） of metal salt simultaneously. The extractive property of three solid extractants towards cation and anion（s） of metal salts （sulfate, nitrate and chloride） have been tested by employing Atomic Absorption Spectrometry and Ion Chromatography techniques. Experimental results showed that the extraction rate higher than 95% were observed for Cu （Ⅱ）, Co （Ⅱ）, Ni （Ⅱ） and Fe （Ⅱ）, while the extraction for Zn （Ⅱ） and Mn （Ⅱ） varied from different metal salts and displayed a value between 62-96% and 52-94% for Zn（Ⅱ）and Mn（Ⅱ）, respectively. The extraction rate for anions showed marked difference between different metal salts, and the extraction rate were lower than that for cations. The maximum extraction rate for SO₄^2-, Cl^- and NO₃^- were 88%, 64 and 64%, respectively.5. The different extraction efficiency towards cations and anions and the affect of attendant ions were preliminarily analysed, with a view that it will supply some clue for further understanding the mechanisms, the design of efficient ligand and optimization of extraction conditions.更多还原