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Contribution of partially labile complexes to the DGT metal flux.

Authors
  • Uribe, Ramiro
  • Mongin, Sandrine
  • Puy, Jaume
  • Cecília, Joan
  • Galceran, Josep
  • Zhang, Hao
  • Davison, William
Type
Published Article
Journal
Environmental Science & Technology
Publisher
American Chemical Society (ACS)
Publication Date
Jun 15, 2011
Volume
45
Issue
12
Pages
5317–5322
Identifiers
DOI: 10.1021/es200610n
PMID: 21608530
Source
Medline
License
Unknown

Abstract

Penetration of complexes into the resin layer can dramatically increase the contribution of complexes to the metal flux measured with a DGT (diffusive gradients in thin films) sensor, but equations to describe this phenomenon were not available. Here, simple approximate analytical expressions for the metal flux, the lability degree and the concentration profiles in a DGT experiment are reported. Together with the thickness of the reaction layer in the gel domain, the effective penetration distance into the resin layer that would be necessary for full dissociation of the complex (λ(ML)) plays a key role in determining the metal flux. An increase in the resin-layer thickness (r) effectively increases the metal flux and the lability degree until r ≈ 3λ(ML). For the usual DGT configuration, where the thickness of the gel layer exceeds that of the resin layer, the complex is labile if r > (D(ML)/k(d))½, where D(ML) is the diffusion coefficient of the metal complex and k(d) its dissociation rate constant. A general procedure for estimating the lability of any complex in a standard DGT configuration is provided.

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