Affiliation: | a Centre de Recherche Interdépartemental pour le Traitement des Eaux Résiduaires (CRITER), 82, avenue Kléber, 92700, Colombes, France b Bureau Veritas, Direction Régionale Ile de France Construction et Sécurité, 21/23 grande Allée du 12 février 1934, 77186, Noisiel, France c Laboratoire de Bioélectrochimie et d'Analyse du Milieu (LABAM), U.F.R. de Sciences et de Technologie, Université Paris-Val de Marne, Avenue du Général de Gaulle, 94100, Créteil Cedex, France |
Abstract: | Cupric ion fixation by raw peat is likely involved in both cation exchange with H+, Ca2+, Mg2+ and adsorption-complexation, i.e. fixation of the same equivalent of copper ions and anions (NO3?) without any ion release. The importance of both reactions depends largely on initial copper concentration, peat type and pH. Isotherms of copper (initial concentration ranging between 1 and 20 mM) fixation on two types of peat (eutrophic and oligotrophic peat at 30 g d.w./l at pH ranging between 2 and 4) showed that the higher the initial cupric concentration, the more important is this complexation reaction; over this initial cupric concentration range, ion exchange sites were relatively saturated and reached 308 and 101 mmol/kg d.w. for eutrophic and oligotrophic peat whereas no saturation was found for complexation sites, their capacity attaining up to 74 and 119 mmol/kg d.w., respectively. The apparent equilibrium constant for ion exchange with acid-treated peat (initial pH 4.0, 30 g d.w./l) for various metal binding on both peat sites ranged between 1.1 and 10.8 in 15 mM metallic solutions. The apparent affinity in batch conditions for 5 elements may be compared according to the apparent global equilibrium constants, ranging between 1.1 × 10?6 and 20.2 × 10?6: Pb > Cu > Ca > Mg, Zn for eutrophic peat and Pb > Ca > Cu > Mg, Zn for oligotrophic peat. |