【作者】 周祥凤；

【导师】 李德亮；

【作者基本信息】 河南大学 ， 分析化学， 2012， 硕士

【摘要】 络合萃取是通过对待分离溶质的官能团与络合剂的官能团之间化学反应，然后通过温度或pH值变化实现反萃，溶质可回收，萃取剂可循环使用的新型分离技术，它对极性有机物稀溶液的分离具有高效性和高选择性。两性化合物同时具有Lewis酸和Lewis碱两种官能团，具有独特的化学、物理和生物性质。本文选用二（2-乙基己基）磷酸（D2EHPA）为络合剂，以正辛醇和煤油为稀释剂和D2EHPA+磷酸三丁酯(TBP)为混合萃取剂正辛醇为稀释剂，对羟基吡啶（邻羟基吡啶、间羟基吡啶和对羟基吡啶）进行了较系统的研究，考察了络合剂浓度、稀释剂的种类、水相平衡pH值及溶质浓度对萃取平衡的影响。结果表明：分配比随D2EHPA浓度的增加而增大；随溶质浓度的增加而减小，随水相平衡pH值先增大然后减小，分配比的峰值都出现在羟基吡啶中性分子对应的pH值区域；极性稀释剂(正辛醇)更有利于D2EHPA对羟基吡啶的萃取。用傅立叶红外光谱法对正辛醇和煤油体系中的羟基吡啶、空白有机相和负载有机相进行分析。结果表明：不管是在正辛醇体系下还是在煤油体系中，羟基吡啶的-N-与D2EHPA的-OH缔合成相同结构的离子萃合物；pH值不影响络合萃取的萃取机理。电性参数等是影响萃取平衡的重要因素，在络合萃取羟基吡啶系统实验研究的基础上，初步探讨了稀释剂的种类、溶质的电性参数pKa，pKb及疏水性参数(LgP)对萃取平衡分配比的影响。结果显示：电性参数（pKa，pKb）、疏水性参数(LgP)及稀释剂的种类是影响平衡分配系数的主要因素。协同络合萃取是新近提出的一种分离有机物稀溶液的新方法，它兼具协同萃取、络合萃取二者之优点，具有更显著的高效性和高选择性，并且已成功地用于金属的萃取分离中。本文用D2EHPA+TBP+1-octanol混合络合剂体系对羟基吡啶进行了初步的相平衡实验研究。结果表明：混合萃取剂D2EHPA+TBP+1-octanol对羟基吡啶都具有明显的协萃效应；对邻羟基吡啶、间羟基吡啶和对羟基吡啶存在最佳萃合比（Rs），与D2EHPA单萃羟基吡啶的规律一样，分配比随着混合萃取剂浓度的增加而增大；随pH值的增加先增大后减小；与羟基吡啶中性分子缔合形成萃合物。通过红外光谱分析，协同-络合萃取过程中可能同时存在D2EHPA和TBP单独对溶质的络合反应和混合萃取剂共同对溶质的协同萃取效应。更多还原

【Abstract】 Reactive extraction is a new separation technique that is a chemical reaction of functional group of thesolutes separated and extractants, then obtained the regained rolutes and the recycled extractants bychanging pH and temperature. It possesses of high efficiency and high selectivity for polar organicseparation of dilute solution.Amphoteric compounds, which contain two typical functional groups of Lewis acidic and Lewis basicgroups, possess of particular physical, chemical and biological properties. Reactive extractions of a kind ofamphoteric compounds named hydroxypyridine including o-hydroxypyridine, m-hydroxypyridine,p-hydroxypyridine, using Di(2-ethylhexyl)phosphoric acid(D2EHPA)in1-octanol and kerosene andD2EHPA+tributylphosphate (TBP) in1-octanol as extractants, were systematically studied. The influencesof the concentration of extractants, the type of diluents, the pH value of aqueous solutionand and the initialconcentration of hydroxypyridine on distribution coefficient (D) were discussed. The result displays thatthe D increased with the increase of the concentration of D2EHPA, decreased with the increase of theconcentration of hydroxypyridine and the D increased with the increase of the pH value first then decreasedand the peak value of the D appears the neutral molecules of hydroxypyridine of the corresponding pHvalue area. Polar dilutes(1-octanol) provide with higher D for extracting hydroxypyridine with D2EHPA.The interaction mechanisms between D2EHPA in1-octanol and kerosene and hydroxypyridine werevalidated with Infrared spectroscopic analysis by comparing the characteristic peaks change of thefunctional groups with the solute, the extractant and the loading organic phase. The effect of the variouspH on the interaction mechanisms was analysised. The results showed: it could be concluded D2EHPAmainly reacted with hydroxypyridine to form ion-pair complexes through its–OH interacting with–N–ofhydroxypyridine to form the complexes of the same structure whether in1-octanol or kerosene. The pHvalue of the aqueous solution has no influence on the interaction mechanisms.The electronic parameters of solutes (i.e. pKa,pKband lgP) were of great influences on extractionequilibrium. Based on the experiment of reactive extraction on hydroxypyridine, the effect of the electronicparameters and the type of dilutes on the D was preliminarily studied. The results showed: the electronicparameters(pKa,pKb),the lipophilicity parameters (lgP) and the type of the dilutes has great influence on the D.The synergistic extraction is a new separation method separaed the dilute solution of the organicmatter put forward recently. It possesses of the both merits of synergistic and reactive extraction,possessing of higher efficiency and higher selectivity, and has been successfully used in the metalextraction separation. The extraction of hydroxypyridine using the composite extractants(D2EHPA andTBP) in1-octanol was preliminarily studied. The result showed: It was obvious synergistic effect onhydroxypyridine between D2EHPA and TBP in1-octanol. It exists the best tatio of D2EHPA to TBP incomposite extractants. It was the same trendency comparing to the single extraction, the D increased withthe increase of the concentration of mixtured extractants(the constant Rs) and the increase first and thendecrease with the increase of the pH value. The mixtured extractants and hydroxypyridne form the ion-complexes. The separaed extraction and the synergistic extraction exist simultaneously in the synergisticprocess using D2EHPA and TBP in1-octanol.更多还原