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

对有毒重金属离子具有特异结合能力的螯合材料的开发已受到广泛关注。特别是从环境和生物系统中选择性去除铅（II）是一个重要的目标。本课题制备了具有不同间隔单元的二苯并聚醚二羧酸，用于铅（II）的选择性分离。研究了从不同pH的缓冲水溶液中提取Pb （II）和Cu （II）到氯仿的分子结构。具有乙烯间隔单元的1,5-二[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。延长间隔基团至二甘醇会降低萃取效率和选择性。由于结合位点存在空间应力，承载刚性苯间隔单元的三苯配体对Pb （II）和Cu （II）的萃取有明显的抑制作用。这些单体与甲醛在甲酸中的缩聚聚合提供了稳定的螯合树脂，该树脂含有离子交换和聚醚结合位点，用于金属络合。具有乙烯间隔基的二羧酸树脂是一种分离铅（II）的有效螯合树脂。所观察到的Pb （II）对Cu （II）的吸附选择性达到200。研究了其吸附机理和选择性，并与市售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.