Mécanisme de rétention du cuivre sur de la tourbe végétalisée

Abstract : The high retention capacity of peat can be used to purify wastewaters before their release into the environment. Industrially, this capacity is used in a process called "Jardin Filtrant$^{\text{TM}}$", developed by the Phytorestore company. In this process, wastewaters are filtered through pots, filled with carex (CP) and sphagnum (SP) peat and vegetated with wetland plants, such as Phragmites australis (P.a.). The purpose of this research project was to improve the efficiency of the process through understanding the mechanisms of retention of copper on peat particles and the interface peat / root. These interactions are known to influence the mobility and bioavailability of ET. Three approaches have been implemented. The chemical approach (titrations and adsorption isotherms) showed that SP has a higher reactivity CP in terms of proton exchange (QH,tot= 3.88 vs. 3.64 mmol/g) than the affinity for copper (log KCu,COOH}= 1.71 vs. 1.30). The approach spectroscopic (EXAFS and XANES) showed that for levels between 100 and 300 ppm Cu form a predominantly double chelate five atoms of the type Cu (malate) 2 with mixed groupings-OH R-COOH. At higher levels, it is complexed by the dicarboxylic groups R-COOH and-COOH form a chelate six atoms of the type Cu (malonate). The micro-spectroscopy (μ-EXAFS and μ-XANES) showed that the two previous complexes predominate in the locker peat. Rhizosphere criminal also contains grains of brass and organo-mineral aggregates of nanocrystalline copper metal. The former are of anthropogenic origin and biological seconds.
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Anthony Matynia. Mécanisme de rétention du cuivre sur de la tourbe végétalisée. Géochimie. Université Joseph-Fourier - Grenoble I, 2009. Français. ⟨tel-00491360v3⟩

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