Voltammetric Analysis of Heterogeneity in Metal Ion Binding by Humics
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- 作者：Francisco Berbel ; José ; Manuel Dí ; az-Cruz ; Cristina Ariñ ; o ; Miquel Esteban ; Francesc Mas ; Josep Lluí ; s Garcé ; s ; and Jaume Puy
- 刊名：Environmental Science & Technology
- 出版年：2001
- 出版时间：March 15, 2001
- 年：2001
- 卷：35
- 期：6
- 页码：1097 - 1102
- 全文大小：97K
- 年卷期：v.35,no.6(March 15, 2001)
- ISSN：1520-5851
文摘
The complexation of Cd, Pb, and Cu by fulvic acids at afixed pH and ionic strength is studied by means of differentvoltammetric techniques at any metal-to-ligand ratio.When using Reverse Pulse Polarography (RPP) the complexspecies are electrochemically labile and not subject tosignificant electrodic adsorption. RPP titrations of fulvic acidwith metal ions are interpreted on the basis of a recentlyproposed analytical expression for limiting currentsvalid for fully labile heterogeneous complexation. Thevoltammetric data are transformed into the correspondingbinding curve, i.e., the fraction of occupied sites vs freemetal concentration. Finally, the competition between metalions and protons in their interaction with the fulvicbinding sites as well as the concomitant polyelectrolyticeffects are analyzed in terms of the NICCA-Donnan model.The results show that voltammetric techniques can beapplied to the studies of heterogeneous complex systemsin a broad range of metal-to-ligand ratios.