title: Kilogram-scale synthesis of iron oxy-hydroxides with improved arsenic removal capacity: study of Fe(II) oxidation--precipitation parameters.
abstract: Various iron oxy-hydroxides were synthesized in a continuous flow kilogram-scale production reactor through the precipitation of FeSO(4) and FeCl(2) in the pH range 3-12 under intense oxidative conditions to serve as arsenic adsorbents. The selection of the optimum adsorbent and the corresponding conditions of the synthesis was based not only on its maximum As(III) and As(V) adsorption capacity but also on its potential efficiency to achieve the arsenic health regulation limit in NSF challenge water. As a result, the adsorbent prepared at pH 4, which consists of schwertmannite, was selected because it exhibited the highest adsorption capacity of 13 μg As(V)/mg, while maintaining a residual arsenic concentration of 10 μg/L at an equilibrium pH 7. The high surface charge and the activation of an ion-exchange mechanism between SO(4)(2-) adsorbed in the Stern layer and arsenate ions were found to significantly contribute to the increased adsorption capacity. Adsorption capacity values observed in rapid scale column experiments illustrate the improved efficiency of the qualified adsorbent compared to the common commercial arsenic adsorbents.
authors: Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece.
authors: Sofia
authors: S
authors: Tresintsi
authors: Konstantinos
authors: K
authors: Simeonidis
authors: George
authors: G
authors: Vourlias
authors: George
authors: G
authors: Stavropoulos
authors: Manassis
authors: M
authors: Mitrakas
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000032:analysis / Q000302:isolation & purification*; D060766:Drinking Water / Q000737:chemistry*; D005290:Ferric Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D005290:Ferric Compounds; D005296:Ferrous Compounds; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide; C020748:ferrous sulfate; D001151:Arsenic; C029451:ferrous chloride