title: Sorption of selenium(IV) and selenium(VI) onto natural iron oxides: goethite and hematite.
abstract: Selenium is a toxic element with a relatively high mobility in the natural waters. Iron oxy-hydroxides might play an important role in the migration of this element as well as on its removal from contaminated water. In this work we study the interaction of Se(IV), and Se(VI) with natural iron oxides hematite and goethite through two series of batch experiments at room temperature. In the first series, sorption as a function of initial selenium concentration is studied and the results have been fitted with Langmuir isotherms. In a second series of experiments, sorption is studied as a function of pH, being the main trend an increase of the sorption at acidic pH. The variation of the sorption with pH has been modelled with a triple layer surface complexation model and using the FITEQL program. The experimental data have been modelled considering for the Se(IV) the formation of the FeOSe(O)O(-) complex onto the hematite surface, and a mixture of FeOSe(O)O(-), and FeOSe(O)OH onto the goethite surface. For Se(VI) the surface complex considered is FeOH(2)(+)-SeO(4)(2-) on both goethite and hematite.
authors.affiliation: Department of Chemical Engineering, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain
authors.forename: Miquel
authors.initials: M
authors.lastname: Rovira
authors.forename: Javier
authors.initials: J
authors.lastname: Giménez
authors.forename: María
authors.initials: M
authors.lastname: Martínez
authors.forename: Xavier
authors.initials: X
authors.lastname: Martínez-Lladó
authors.forename: Joan
authors.initials: J
authors.lastname: de Pablo
authors.forename: V
authors.initials: V
authors.lastname: Martí
authors.forename: L
authors.initials: L
authors.lastname: Duro
mesh_terms: D000327:Adsorption; D004785:Environmental Pollutants / Q000737:chemistry* / Q000302:isolation & purification; D005290:Ferric Compounds / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds / Q000737:chemistry*; D008903:Minerals; D012643:Selenium / Q000737:chemistry* / Q000302:isolation & purification; D018505:Waste Management / Q000379:methods*
chemical_list: D004785:Environmental Pollutants; D005290:Ferric Compounds; D058085:Iron Compounds; D008903:Minerals; C094886:goethite; C000499:ferric oxide; D012643:Selenium; D052203:Ferrosoferric Oxide