DEVELOPMENT OF NOVEL, POLYETHER CHELATING RESINS FOR USE IN SELECTIVE LEAD (II) SEPARATION

开发对有毒重金属离子具有特异性结合能力的螯合材料受到了广泛的关注。特别是从环境以及从生物系统中选择性地去除Pb（II）是一个重要的目标。在本项目中，已制备了具有不同间隔基单元的二苯并聚醚二羧酸用于选择性分离Pb（II）。从不同pH值的缓冲水溶液中萃取Pb（II）和Cu（II）到氯仿中，研究了它们的分子结构。具有乙烯间隔单元的1，5-双[2-（2 ′-羧基癸氧基）苯氧基]乙烷对Pb（II）的萃取选择性比Cu（II）高800。延长二甘醇的间隔基团降低了萃取效率和选择性。由于结合位点的空间应力，带有刚性苯间隔单元的三苯并配体对Pb（II）和Cu（II）的萃取表现出显著的抑制。这些单体与甲醛在甲酸中的缩聚提供了稳定的螯合树脂，其含有用于金属络合的离子交换和聚醚结合位点。乙烯基二元羧酸树脂被认为是一种有效的螯合树脂分离铅（II）。所观察到的吸附选择性铅（II）超过铜（II）达到200。研究了吸附机理和选择性，并与市售的亚氨基二乙酸树脂进行了比较。

The development of chelating materials possessing specific binding ability toward toxic heavy metal ions has received considerable attention. Especially selective removal of Pb (II) from environment as well as from biological system is an important objective. In this project, dibenzopolyether dicarboxylic acids possessing different spacer units have been prepared for use in selective Pb (II) separation. The extraction of Pb (II) and Cu (II) from buffered aqueous solution of varying pH into chloroform is examined in relation to their molecular structure. 1,5-Bis [2-(2'-carboxydecyloxy) phenoxy] ethane which has an ethylene spacer unit exhibits excellent extraction selectivity of 800 for Pb (II) over Cu (II). Lengthening the spacer group to diethylene glycol diminishes the extraction efficiency and selectivity. Due to a steric stress of the binding site, tribenzo ligand bearing rigid benzene spacer unit shows a significant depression for the extraction of Pb (II) and Cu (II). Condensation polymerization of these monomers with formaldehyde in formic acid provides stable chelating resins which contain both ion-exchange and polyether binding sites for metal complexation. Dicarboxylic acid resin with an ethylene spacer group is found to be an effective chelating resin for Pb (II) separation. The observed sorption selectivity for Pb (II) over Cu (II) reaches 200. The sorption mechanism and selectivity are studied and compared with the commercially available iminodiacetic acid resins.