Speciation of nickel in surface waters measured with the Donnan membrane technique

The evaluation of the ecotoxicological risk of nickel (Ni) in surface water is hampered by a lack of speciation data. Six surface waters were sampled and speciation of Ni(II) was measured by the Donnan membrane technique (DMT) combined with radiochemical determination of 63Ni. The free Ni 2+ ion fra...

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Bibliographic Details
Published in:Analytica chimica acta 2006-09, Vol.578 (2), p.195-202
Main Authors: Van Laer, Liesbeth, Smolders, Erik, Degryse, Fien, Janssen, Colin, De Schamphelaere, Karel A.C.
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemistry
Donnan membrane technique (DMT)
Exact sciences and technology
Nickel speciation
Radiochemical methods
Surface water
Windermere Humic Aqueous Model (WHAM)
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Summary:The evaluation of the ecotoxicological risk of nickel (Ni) in surface water is hampered by a lack of speciation data. Six surface waters were sampled and speciation of Ni(II) was measured by the Donnan membrane technique (DMT) combined with radiochemical determination of 63Ni. The free Ni 2+ ion fraction in the dissolved ( two-fold), even when assuming that all dissolved organic matter (DOM) was present as fulvic acid (FA). The impact of several model parameters affecting the prediction of Ni speciation were evaluated, including the solubility product of Fe(OH) 3, which affects the Fe competition for complexation by DOM. The best fit ( R 2 = 0.88) was obtained by increasing only the distribution term ΔLK 2, which modifies the binding strength of multi-dentate sites, to accommodate the observed dependence of free ion fraction on Ni concentration.
ISSN:0003-2670
1873-4324
DOI:10.1016/j.aca.2006.06.070