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

点击翻译按钮获取中文摘要

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.