title: Tetravalent manganese feroxyhyte: a novel nanoadsorbent equally selective for As(III) and As(V) removal from drinking water.
abstract: The development of a single-phase Fe/Mn oxy-hydroxide (δ-Fe0.76Mn0.24OOH), highly efficient at adsorbing both As(III) and As(V), is reported. Its synthesis involves the coprecipitation of FeSO4 and KMnO4 in a kilogram-scale continuous process, in acidic and strongly oxidizing environments. The produced material was identified as a manganese feroxyhyte in which tetravalent manganese is homogeneously distributed into the crystal unit, whereas a second-order hollow spherical morphology is favored. According to this structuration, the oxy-hydroxide maintains the high adsorption capacity for As(V) of a single Fe oxy-hydroxide combined with enhanced As(III) removal based on the oxidizing mediation of Mn(IV). Ion-exchange between arsenic species and sulfates as well as the strongly positive surface charge further facilitate arsenic adsorption. Batch adsorption tests performed in natural-like water indicate that Mn(IV)-feroxyhyte can remove 11.7 μg As(V)/mg and 6.7 μg As(III)/mg at equilibrium pH 7, before residual concentration overcomes the regulation limit of 10 μg As/L for drinking water. The improved efficiency of this material, its low cost, and the possibility for scaling-up its production to industry indicate the high practical impact and environmental importance of this novel adsorbent.
authors.affiliation: Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki , 54124 Thessaloniki, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Tresintsi
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Simeonidis
authors.forename: Sonia
authors.initials: S
authors.lastname: Estradé
authors.forename: Carlos
authors.initials: C
authors.lastname: Martinez-Boubeta
authors.forename: George
authors.initials: G
authors.lastname: Vourlias
authors.forename: Fani
authors.initials: F
authors.lastname: Pinakidou
authors.forename: Maria
authors.initials: M
authors.lastname: Katsikini
authors.forename: Eleni C
authors.initials: EC
authors.lastname: Paloura
authors.forename: George
authors.initials: G
authors.lastname: Stavropoulos
authors.forename: Manassis
authors.initials: M
authors.lastname: Mitrakas
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D018360:Crystallography, X-Ray; D060766:Drinking Water / Q000737:chemistry*; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D060766:Drinking Water; D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide; D008345:Manganese; D001151:Arsenic