Contribution of Partially Labile Complexes to the DGT Metal Flux

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• 作者：Ramiro Uribe ; Sandrine Mongin ; Jaume Puy ; Joan Cec铆lia ; Josep Galceran ; Hao Zhang ; William Davison
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：June 15, 2011
• 年：2011
• 卷：45
• 期：12
• 页码：5317-5322
• 全文大小：816K
• 年卷期：v.45,no.12(June 15, 2011)
• ISSN：1520-5851

文摘

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 (位_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 鈮?3位_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)^1/2, 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.