Study of the interaction between humic acids and lead :

Exchange between Pb2+ and H+ under various chemical conditions followed by FTIR

P. Gossart1, A. Semmoud1, B. Ouddane2, J.-P. Huvenne1*

1 LASIR, Laboratoire de Spectrochimie Infrarouge et Raman, CNRS, UMR 8516, Bat.C5,

Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France

2 ELICO, Laboratoire de Chimie Analytique et Marine, CNRS, UPRESA 8013, Bat.C8,

Université des Sciences et Technologies de Lille,59655 Villeneuve d'Ascq Cedex, France

* Corresponding author. E-mail : jean-pierre.huvenne@univ-lille1.fr

Received : 17 January 2002; revised version accepted : 10 October 2002

Abstract

An infrared spectroscopic investigation of a Pb2+/humic acids interaction is achieved to determine the behaviour of reactive sites in the binding with heavy metals under various chemical conditions. The pH and the initial lead concentration are the two chemical variables studied in order to follow exchanges between Pb2+ and H+ with commercial and natural humic acids. After a validation of FTIR within the context of the study, a correlation between spectroscopic and chemical variables is proved to be possible. For a selected pH and initial lead rate, FTIR spectrum of a given humic acid seems to be specific to these chemical conditions. For the different studied forms of HA, we observe a large capacity to absorb heavy metals as lead. The comparison of the different results and their dependances on different conditions permits to propose reactional mechanism of the lead/HA interaction.

Keywords : FTIR; Humic acids; Lead; Interaction.

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