title: Equilibrium and kinetics studies on As(V) and Sb(V) removal by Fe2+ -doped Mg-Al layered double hydroxides.
abstract: Mg-Al layered double hydroxides (Mg-Al LDHs) doped with Fe(2+) adsorbed As(V) [Formula: see text] and Sb(V) [Formula: see text] from an aqueous solution through anion exchange with Cl(-) intercalated in the LDH interlayer. Fe(2+)-doped Mg-Al LDH exhibited superior As(V) removal compared with Mg-Al LDH. The oxidation of Fe(2+) doped in the Mg-Al LDH host layer to Fe(3+) increased the positive layer charge of the LDH, thus increasing the anion-uptake capacity owing to stronger electrostatic attractive force between the positively charged layer and the anion. However, Fe(2+)-doped Mg-Al LDH was not superior to Mg-Al LDH in terms of Sb(V) removal. This was attributed to the preferential intercalation of OH(-) over [Formula: see text] . The As(V) and Sb(V) removal by LDH followed Langmuir-type adsorption, which proceeded via a pseudo-first-order reaction. The equilibrium and kinetics studies confirm that the adsorption of As(V) and Sb(V) by Fe(2+)-doped Mg-Al LDH was the result of chemical adsorption, involving the anion exchange of [Formula: see text] and [Formula: see text] with the intercalated Cl(-).
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan. Electronic address: kameda@env.che.tohoku.ac.jp.
authors.forename: Tomohito
authors.initials: T
authors.lastname: Kameda
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Kondo
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yoshioka
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D000965:Antimony / Q000737:chemistry*; D001151:Arsenic / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D006878:Hydroxides; D017616:Magnesium Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D000965:Antimony; D007501:Iron; D001151:Arsenic
keywords: As(V); Equilibrium; Fe(2+); Kinetics; Layered double hydroxide; Sb(V)