title: Transport of selenium oxyanions through TiO2porous media: column experiments and multi-scale modeling.
abstract: The present work deals with the modeling of selenium oxyanion (selenite/selenate) retention in TiO2 rutile porous media. A set of chemical interactions was elaborated from spectroscopic measurements and adsorption experiments in batch and column reactors, and a model of transient transport of the selenium species through laboratory column was developed. The adsorption model considered that both forms of selenium (Se) compete for the same sorption sites, hydroxyl groups, allowing taking into account a competitive adsorption. Stoichiometry and equilibrium constants of adsorption reactions were determined on the basis of spectrometric measurement and adsorption isotherm curve fitting. This approach led to a model of Sips type isotherm including a pH-dependence. It offers an excellent fitting compared to the classical Langmuir equation and provides a unique set of parameters for both oxyanions. IMPACT code and associated modeling method were then used to couple transport and chemical reactions. The obtained numerical results showed a reasonable prediction of the shape and the time location of selenium oxyanions and pH breakthrough curves.
authors.affiliation: CNRS, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France; Université de Lorraine, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France.
authors.forename: K
authors.initials: K
authors.lastname: Nsir
authors.affiliation: Laboratoire d'Electrochimie et de Physicochimie des Matériaux et des Interfaces, UMR 5279, CNRS/Grenoble-INP/Université de Savoie/Université Joseph Fourrier, 1130 rue de la Piscine, 38402 Saint-Martin d'Hères, France.
authors.forename: L
authors.initials: L
authors.lastname: Svecova
authors.affiliation: CNRS, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France; Université de Lorraine, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France. Electronic address: michel.sardin@univ-lorraine.fr.
authors.forename: M
authors.initials: M
authors.lastname: Sardin
authors.affiliation: CNRS, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France; Université de Lorraine, Laboratoire Réactions et Génie de Procédés, UMR 7274, 1 rue Grandville, BP 20451, 54001 Nancy, France.
authors.forename: M O
authors.initials: MO
authors.lastname: Simonnot
mesh_terms: D000327:Adsorption; D002845:Chromatography; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
chemical_list: D010087:Oxides; D018036:Selenium Compounds; C009495:titanium dioxide; D014025:Titanium
keywords: Batch sorption; Isotherm; Reactive transport modeling; Selenium; TiO(2)