title: A novel approach for arsenic adsorbents regeneration using MgO.
abstract: An integrated procedure for the regeneration of iron oxy-hydroxide arsenic adsorbents by granulated MgO is proposed in this study. A continuous recirculation configuration, with a NaOH solution flowing sequentially through the saturated adsorbent (leaching step) and the MgO (adsorption step) column beds, was optimized by utilizing the high arsenic adsorption efficiency of MgO at strong alkaline environments. Experimental results indicated that the total amount of leached arsenic was captured by MgO whereas the regenerated iron oxy-hydroxide recovered around 80% of its removal capacity upon reuse. The improved adsorption capacity of MgO for As(V), which is maximized at pH 10, is explained by the intermediate hydration to Mg(OH)2 and the following As(V) oxy-anions adsorption on its surface through the formation of monodentate inner sphere complexes, as it is deduced from the AsK-edge X-ray absorption fine structure (EXAFS) analysis. In addition to the economical-benefits, corresponding tests proved that the solid wastes of this process, namely spent MgO/Mg(OH)2, can be environmentally safely disposed as stable additives in cement products, while the alkaline solution is completely detoxified and can be recycled to the regeneration task.
authors.affiliation: Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Greece. Electronic address: stresint@physics.auth.gr.
authors.forename: Sofia
authors.initials: S
authors.lastname: Tresintsi
authors.affiliation: Department of Mechanical Engineering, University of Thessaly, 38334 Volos, Greece. Electronic address: ksime@physics.auth.gr.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Simeonidis
authors.affiliation: Department of Physics, Aristotle University of Thessaloniki, 54124, Greece. Electronic address: katsiki@auth.gr.
authors.forename: Maria
authors.initials: M
authors.lastname: Katsikini
authors.affiliation: Department of Physics, Aristotle University of Thessaloniki, 54124, Greece. Electronic address: paloura@auth.gr.
authors.forename: Eleni C
authors.initials: EC
authors.lastname: Paloura
authors.affiliation: Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Greece. Electronic address: bantsis_george@yahoo.gr.
authors.forename: Georgios
authors.initials: G
authors.lastname: Bantsis
authors.affiliation: Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Greece. Electronic address: manasis@eng.auth.gr.
authors.forename: Manassis
authors.initials: M
authors.lastname: Mitrakas
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D059027:Recycling; D012972:Sodium Hydroxide / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide; D008277:Magnesium Oxide; D012972:Sodium Hydroxide; D001151:Arsenic
keywords: Adsorbents regeneration; Arsenic removal; Drinking water; Magnesium oxide; RSSCT; XAFS