Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 66300
Title Determination of the chemical speciation of trace metals in aqueous systems by the WDMT
Author(s) Temminghoff, E.J.M.; Plette, A.C.C.; Eck, R. van; Riemsdijk, W.H. van
Source Analytica Chimica Acta 417 (2000). - ISSN 0003-2670 - p. 149 - 157.
Department(s) Sub-department of Soil Quality
Publication type Refereed Article in a scientific journal
Publication year 2000
Abstract In order to determine the 'free' metal ion concentration in aqueous solutions the so-called Wageningen Donnan Membrane Technique (WDMT) has been developed. This involves a continuous flow system in which the donor side and the acceptor side of the WDMT cell are continuously flushed with solution across the membrane. The new cell design allows pseudo equilibrium to be reached for the free metal ions via a Donnan equilibrium across a negatively charged ion-exchange membrane within a reasonable time span. The donor solution contains both 'free' and complexed metal ions. The concentration of the cations in the acceptor solution is either equal to the concentration of the 'free' cation concentration in the donor solution, or it can be calculated using simple correction factors. The optimization experiments have been performed with cadmium and copper, in the presence of various (in)organic complexing agents, at various pH values, and different salt concentrations. In multi-component systems, like the systems used for the experiments with calcium, cadmium, copper, protons and EDTA, the results are in good agreement with the speciation calculations. The transport of the different cations and anions across the membrane can be very well explained by the simplified theory presented. Effects of difference in salt concentration on metal concentrations can be corrected. For the more complicated systems with natural dissolved organic matter (e.g. humic acid) the concentrations measured in the acceptor solution are also in good agreement with the speciation calculations performed for the donor solution.
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