Adsorption of metal-ethylenediaminetetraacetic acid chelates onto lake sediment

The adsorption of Ethylenediaminetetraacetic acid (EDTA) and its metal comp lexes, Cu, Fe(III), Hg, Mn and Ni, onto lake sediment was studied. The resu lts reveal that EDTA and metal-EDTA complexes, even though being hydrophili c compounds, are indeed adsorbed within one months' contact time to some ex tent (6.3-24.8%). Less than 10% of Ni-EDTA, Cu-EDTA and EDTA salt was adsor bed, while the mass amount of Mn-EDTA, Hg-EDTA and Fe(III)-EDTA found in se diment exceeded 15% after the contact period. Thus, adsorption of metal-EDT A chelates might be a relevant process in their removal from the aquatic en vironment. The metal-EDTA chelates in aqueous and solid phases were determi ned by gas chromatography-nitrogen phosphorus detection (GC-NPD) system. Th e complexes were extracted by phosphate solution prior to analysis. The abi lity of EDTA to desorb adsorbed heavy metals from sediments is also discuss ed. (C) 2001 Elsevier Science Ltd. All rights reserved.