title: Effect of co-existing ions during the preparation of alumina by electrolysis with aluminum soluble electrodes: structure and defluoridation activity of electro-synthesized adsorbents.
abstract: The electrochemical dissolution of aluminum was carried out to prepare hydrated aluminas which were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), chemical titrations and defluoridation activities. Aluminas were obtained at controlled pH depending upon the counter cations of the electrolyte. A boehmite AlOOH phase was isolated mainly in ammonium solution, while aluminas synthesized in the other media contained a mixture of phases, usually both boehmite and bayerite γ-Al(OH)₃. All the boehmite phases contained nano-crystallites of less than 3 nm. Batch defluoridation experiments revealed a second influence of the original electrolyte. Aluminas were very effective in defluoridation with abatement rates of 99.5%, 98.5% and 97.3% from neutral fluoride solution at 10 mgL(-1) when they were prepared in solution of (NH₄)₂SO₄, (NH₄)HCO₂ and NH₄Cl, respectively. The maximum fluoride capacities were 46.94; 10.25 and 12.18 mg g(-1) for aluminas prepared in solution of (NH₄)₂SO₄; (NH₄)HCO₂ and NH₄Cl, respectively. The amount of dissolved Al was found to be less than 0.19 mgL(-1) at neutral pH. These results show that a defluoridation with electro-synthesized aluminas would be more efficient and safe than a direct electrocoagulation.
authors.affiliation: UMR CNRS n°6226 Institut des Sciences Chimiques de Rennes, ENSCR, Avenue du Général Leclerc, CS 50837 - 35708 Rennes Cedex 7, France; Laboratoire de Chimie Analytique, Faculté des Sciences, Université de Yaoundé-I, BP 812 Yaoundé, Cameroon. Electronic address: etchomgui@yahoo.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Tchomgui-Kamga
authors.affiliation: UMR CNRS n°6226 Institut des Sciences Chimiques de Rennes, Université de Rennes-1, Avenue du Général Leclerc, 35042 Rennes Cedex, France. Electronic address: nathalie.audebrand@univ-rennes1.fr.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Audebrand
authors.affiliation: UMR CNRS n°6226 Institut des Sciences Chimiques de Rennes, ENSCR, Avenue du Général Leclerc, CS 50837 - 35708 Rennes Cedex 7, France. Electronic address: Andre.Darchen@ensc-rennes.fr.
authors.forename: André
authors.initials: A
authors.lastname: Darchen
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D004566:Electrodes; D004572:Electrolysis; D005459:Fluorides / Q000737:chemistry*; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D014874:Water Pollutants, Chemical; D000535:Aluminum; D000537:Aluminum Oxide; D005459:Fluorides