Abstract: Extraction equilibrium behavior of p-aminophenol is studied by using TRPO as extractant，and n-octanol or heptane as diluent.The distribution coefficient，D，is measured at various pH values.Mathematics models are proposed to describe the equilibrium behavior based on the physical extraction and reactive extraction of solvent.Results show that neutral p-aminophenol is hydrogen bonded and solvated to TRPO into the organic phase，and D value depends on the fraction of neutral p-aminophenol and TRPO concentration，but does not depend on the diluents apparently.The apparent reactive extraction constant，K，is almost constant in various solvents (about 10 with 10% deviation) except for 20%TRPO/n-octanol condition.The physical distribution constant，m，increased with TRPO concentration，and equivalent to additive of the physical extraction ability of diluent and TRPO.p-Aminophenol can be extracted with both acidic and basic extractants efficiently，the extraction ability shows the order of di(2-ethylhexyl)phosphoric acid＞TRPO＞Alamine 336，and their efficient pH region is 2—3，4—5， and 6.5—7.5 respectively.When extraction method is used to separate p-aminophenol solution，the extractant should be selected based on pH value of the practical solution to avoid the adverse effect of salt produced from adjusting pH.

Key words:

反应萃取, 对氨基苯酚, 三烷基氧磷

摘要： 以三烷基氧磷(TRPO)为反应萃取剂，研究了稀释剂种类、溶液pH值等因素对对氨基苯酚稀溶液反应萃取分配系数(D)的影响，提出了同时考虑反应萃取和物理萃取作用的分配系数的表达式.结果表明：TRPO对对氨基苯酚的萃取主要通过与其中性分子的氢键缔合和溶剂化效应实现，D值的变化与中性分子的摩尔分数有关；稀释剂的极性对对氨基苯酚的萃取影响较小；除20%TRPO/正庚烷体系外，拟合实验数据得到的表观萃取平衡常数变化较小；体系的物理萃取分配常数则随TRPO浓度的增大而增大，且符合稀释剂和TRPO的物理萃取能力的简单加和；酸性、碱性和中性的反应萃取剂都可有效地萃取对氨基苯酚，萃取能力为二(2-乙基己基)磷酸＞ TRPO ＞ 三烷基胺，相应的操作pH值为2～3、4～5和6.5～7.5，应用时可根据体系的pH值范围选用相应的萃取剂，而不必调节溶液的pH值.

关键词:

反应萃取, 对氨基苯酚, 三烷基氧磷