三烷基氧膦与二(2-乙基己基)磷酸协萃对氨基苯酚的研究和应用

为考察复合萃取剂萃取两性官能团溶质的协萃机理,以对氨基苯酚(PAP)为分离溶质,三烷基氧膦(TRPO)+二(2 乙基己基)磷酸(D2EHPA)+庚烷为萃取剂进行了萃取平衡特性的研究。结果表明,该萃取剂萃取PAP时,具有明显的协萃效应。协萃机理为TRPO与PAP的中性分子以及D2EPHPA与PAP的中性分子和阳离子反应生成(HP)2·NH2—C6H4—OH·TRPO或者P·NH3—C6H4—OH·TRPO萃合物;萃取剂中D2EHPA与TRPO的适宜协萃比为1∶3;pH是影响萃取能力的关键因素,起始pH值条件下PAP分子形态摩尔分数较大的pH值区域(6—8),分配系数出现极大值;采用适宜的萃取剂组成对PAP的工业生产废水进行处理,可有效去除废水中的PAP和苯胺。

Synergistic extraction behavior and application of p-aminophenol with TRPO and D2EHPA

Synergistic extraction of p-aminophenol (PAP)by the mixture extractant of D2EHPA and TRPO was studied under various initial pH.The results show that the extraction of p-aminophenol with the mixed solvent (presents) the synergistic effect by TRPO bonded to neutral p-aminophenol and D2EHPA associated with (neutral) paminophenol and ion p-aminophenol, i.e. (HP)_2·NH_2—C_6H_4—OH·TRPO or P·NH_3—C_6H_4—OH·(TRPO).The molar concentration ratio of D2EHPA to TRPO at 1∶3 is the synergistic point, the degree of (extraction) for PAP (depends) on the initial pH obviously, and the maximum distribution coefficient appears at initial pH value between pK_(a1) and pK_(a2). This pH dependence can be explained by varying the molar fraction of neutral and ion( p-aminophenol) with pH value. The removal of p-aminophenol and aniline can be successfully achieved from wastewater by the extraction with the mixed extractant at the synergistic point.