title: Kinetics of nitrite reduction by zinc metal: influence of metal shape on the determination of kinetic parameters.
abstract: Heterogeneous chemical reactions are complicated, especially in the case of competitive reactions. The aim of this study was to investigate the elimination of nitrite (NO2(-)) by applying a metallic reduction using zero-valent zinc (Zn0). The effect of pH, stirring, and metal shape (powder and chips) on the rate and products of nitrite reduction were studied in a batch-stirred reactor. The obtained data have been used to optimize the conditions for metallic reduction of NO2(-) and for kinetic parameters identification. It was found that the dissolution of zinc involves a pseudo-first-order reaction independent of the shape of the metal. Further, the influence of operating conditions on nitrogen (N2) and ammonium (NH4(+)) formation has been determined. It was found that a decrease in pH and in the Zn0 content enhances NH4(+) production. If kinetic parameters can be approximated easily for constant surface area, it was demonstrated that surface evolution had to be integrated for metal powder. Finally, a numerical simulation has been used to determine the kinetic parameters for NO2(-) reduction with zinc powder.
authors.affiliation: Laboratory for Material Engineering of Brittany, University of South Brittany, Lorient Cedex, France. lionel.limousy@univ-ubs.fr
authors.forename: L
authors.initials: L
authors.lastname: Limousy
authors.forename: P
authors.initials: P
authors.lastname: Dutournie
authors.forename: D
authors.initials: D
authors.lastname: Hadjiev
mesh_terms: D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D009573:Nitrites / Q000737:chemistry*; D010084:Oxidation-Reduction; D011208:Powders; D015032:Zinc / Q000737:chemistry*
chemical_list: D009573:Nitrites; D011208:Powders; D015032:Zinc