Importance of ligand speciation in environmental research: A case study

Mika Sillanpää (Corresponding Author), Marjatta Orama, Jaakko Rämö, Aimo Oikari

Research output: Contribution to journalArticleScientificpeer-review

68 Citations (Scopus)


The speciations of EDTA and DTPA in process, waste and river waters are modelled and simulated, specifically to the mode of occurrence in the pulp and paper mill effluents and subsequently in receiving waters. Due to relatively short residence times in bleaching process and waste water treatment and slow exchange kinetics, it is expected that the thermodynamic equilibrium is not necessarily reached. Therefore, the initial speciation plays a key role. As such, the simulations have been extended to the process waters of the pulp and paper industry taking into account estimated average conditions. The results reveal that the main species are; Mn and Ca complexes of EDTA and DTPA in pulp mill process waters; Fe(III) and Mn complexes of EDTA and DTPA in waste waters; Fe(III) and Zn complexes of EDTA and DTPA in receiving waters. It is also shown how the increasing concentration of complexing agents effects the speciation. Alkaline earth metal chelation plays a significant role in the speciation of EDTA and DTPA when there is a noticeable molar excess of complexing agents compared with transition metals.
Original languageEnglish
Pages (from-to)23-31
JournalScience of the Total Environment
Issue number1-3
Publication statusPublished - 2001
MoE publication typeA1 Journal article-refereed


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