【作者】 崔节虎；

【导师】 李德亮；

【作者基本信息】 河南大学 ， 分析化学， 2005， 硕士

【摘要】 基于可逆络合化学反应的萃取分离方法对于极性有机物稀溶液的分离具有高效性和高选择性。根据 Lewis 酸碱理论,在大量文献调研、系统分析络合萃取剂对两性有机物萃取相平衡特征的基础上,本文选用 Lewis 酸性萃取剂——二(2-乙基己基)磷酸(D2EHPA)和 Lewis 碱性萃取剂——磷酸三丁酯(TBP)为络合剂,不同极性的正辛醇、异辛醇、氯仿、四氯化碳、煤油为稀释剂,以典型的两性有机物——邻氨基苯酚、对氨基苯酚、间氨基苯酚为被萃取物质,详细的研究了萃取剂浓度、稀释剂种类和浓度、溶质初始浓度以及水相平衡 pH 对萃取平衡的影响;讨论了水相平衡 pH 值对所形成的络合物结构的影响。采用质量作用定律的方法,建立了同时考虑络合萃取及物理萃取的 D2EHPA-氨基苯酚-稀释剂、TBP-氨基苯酚-稀释剂体系的相平衡分配比表达式。采用傅立叶红外光谱分析了 D2EHPA 和 TBP萃取两性化合物——氨基苯酚的络合萃取机理。研究表明:体系的 pH 值、络合剂的浓度是影响萃取平衡的主要因素;稀释剂的种类和浓度对分配比有一定的影响;氨基苯酚的初始浓度愈低,分配比愈大;D2EHPA 与氨基苯酚同时存在质子转移、离子缔合成盐机制;而 TBP 与氨基苯酚之间是氢键缔合溶剂化机制。 在对两性氨基苯酚络合萃取实验研究的基础上,探讨了 D2EHPA-氨基苯酚-稀释剂、TBP-氨基苯酚-稀释剂中,溶质的电性参数 pKa 、pKb、疏水性参数(LogP)及氢键、溶剂的性质对萃取平衡的影响。结果表明,疏水性参数是影响氨基苯酚萃取平衡的主要因素;电性常数 pKa 对 TBP 萃取体系影响较大,电性常数 pKb 对D2EHPA 萃取体系影响相对较小;在 TBP-氯仿络合体系中,由于氯仿与 TBP 的氢键作用,降低 TBP 对氨基苯酚萃取,使得氯仿作为稀释剂是不合适的。 “pH 摆动效应”是实现萃取剂再生较为简捷的方法,结合溶质的特点,本实验选择硫酸溶液做反萃剂对部分 D2EHPA、TBP 体系进行反萃实验,结果满意。更多还原

【Abstract】 The extraction method based on reversible chemical complexation is highlyeffective and selective for separation polar organic solutes from dilute solution. On thebasis of largely literature survey, di(2-ethylhexyl)phosphate(D2EHPA) and tributylphosphate(TBP) were selected as a typical extractant, as well as o-aminophenol,m-aminophenol, and p-aminophenol, were used as solutes extracted. Five dilutes,1-octanol, 2-octanol, chloroform, kerosene, carbon tetrachloride were investigated fortheir abilities to improve extraction properties of D2EHPA and TBP. The effects ofcomplexing agent concentration, the polarity and concentration of diluents, the initialconcentration of solute and the aqueous equilibrium pH on the extraction equilibriumhave been systematically investigated. The effects of aqueous equilibrium pH on thestructure of the complex were discussed. The models for describing the extractionequilibrium that include chemical complexation and physical dissolving simultaneouslyby using mass action law to D2EHPA-aminophenol and TBP-aminophenol wereproposed. With the FT-IR spectroscopy, the spectra of organic phase loaded with aminophenolare determined. These researches show that pH values of system and concentration ofcomplexing agent were mostly factor on extraction equilibrium. Species andconcentration of diluted agents have definite factor on distribution ratio. The moreinitial concentration of aminophenol is, the more the distribution ratio is. There aretwo courses in the extraction process: ion-association and ion-transfered in the D2EHPA-aminphonel, but hydrogen-bond complexation in TBP-aminophenol. Through research on aminophenol extracted with D2EHPA-phosphate and TBP,the characteristics (structure, pKa, pKb, LogP) of amphoteric organic compound, and thefactors of solvent and hydrogen bonds were discussed on extraction equilibrium. Theseresearches show that hydrophobicity parameter is mostly factor on extractionequilibrium. Electronic parameter pKa has a big factor on extraction systems of TBP, buta less factor on extraction systems of D2EHPA. Because there is hydrogen bondbetween chloroform and TBP, it reduces extraction of aminophenol with TBP, sochloroform as dilute agent don’t suit in this research. “pH swing effect” is a simple method that it is able to make complexing agentregenerated. Sulfuric acid was selected as regeneration agent on the basis of the soluteand process the part of D2EHPA and TBP systems. The result is satisfying.更多还原