Reactive Polymers, 16 (1991/1992) 71-80 Elsevier Science Publishers B.V., Amsterdam 71 ANION EXCHANGE STUDIES OF LEAD-EDTA COMPLEXES MARZENNA R. DUDZINSKA * and DENNIS A. CLIFFORD Environmental Engineering Program, Cullen College of Engineering University of Houston, Houston, TX 77204-4791 (USA) (Received July 26, 1990; accepted in revised form February 5, 1991) This research with anion exchange resins demonstrates the possibility of removing chelated anionic complexes from water. The affinity of various commercially available polystyrene and acrylic resins for the Pb-EDTA complex was established. The effects of pH, competing ions, resin matrix, functionality, and porosity were studied. Keywords: anion exchange studies; lead-EDTA complexes; polystyrene resins; acrylic resin INTRODUCTION Heavy metals, because of their acute poi- soning effects and tendency to accumulate in the human body, are considered to be among the most dangerous nondegradable sub- stances. To protect consumers they must be removed from water. Ion exchange is a logical treatment process to consider because metals are normally ionic or can readily be converted to ions. For more than 40 years, the cation exchanger process has been studied and used for removal of metal cations; however, fewer studies of anionic metal-complex removal have been completed [1]. The focus on cation exchange is not unexpected in light of the fact that heavy metal cations, such as lead, have an extremely high affinity for cation resins. In * Present address: Department of Water & Wastewater Technology, Technical University of Lublin, 20-618 Lublin, Poland. fact, the affinity is so high that efficient re- generation is difficult and complete regenera- tion impossible. It makes sense, then, to seek easier-to-elute ionic forms. Anionic com- plexes represent a class of compounds that could be relevant for heavy metal removal. The number of these anionic complexes is large because in both water and wastewater we find organic substances capable of acting as ligands for metal cations [2]. These complexes are so strong that they often solubilize toxic metals such that their removal by the usual precipitation processes is hindered. Among the naturally occurring organics capable of complexing metals in water are the humic and fulvic acids. How- ever, man-made chelating agents are also found in water. One of the most commonly used chelating agents, ethylenediaminetetraa- cetic acid (EDTA), is not regarded as toxic to man [3], but its presence in wastewater still causes problems. Unlike nitrilotriacetate (NTA), EDTA is resistant to biodegradation, 0923-1137/91/$03.50 © 1991 - Elsevier Science Publishers B.V. All fights reserved