title: Cerium oxide for the destruction of chemical warfare agents: A comparison of synthetic routes.
abstract: Four different synthetic routes were used to prepare active forms of cerium oxide that are capable of destroying toxic organophosphates: a sol-gel process (via a citrate precursor), homogeneous hydrolysis and a precipitation/calcination procedure (via carbonate and oxalate precursors). The samples prepared via homogeneous hydrolysis with urea and the samples prepared via precipitation with ammonium bicarbonate (with subsequent calcination at 500°C in both cases) exhibited the highest degradation efficiencies towards the extremely dangerous nerve agents soman (O-pinacolyl methylphosphonofluoridate) and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) and the organophosphate pesticide parathion methyl. These samples were able to destroy more than 90% of the toxic compounds in less than 10 min. The high degradation efficiency of cerium oxide is related to its complex surface chemistry (presence of surface OH groups and surface non-stoichiometry) and to its nanocrystalline nature, which promotes the formation of crystal defects on which the decomposition of organophosphates proceeds through a nucleophilic substitution mechanism that is not dissimilar to the mechanism of enzymatic hydrolysis of organic phosphates by phosphotriesterase.
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic. Electronic address: pavel.janos@ujep.cz.
authors.forename: Pavel
authors.initials: P
authors.lastname: Janoš
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic; Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Henych
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Pelant
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic.
authors.forename: Věra
authors.initials: V
authors.lastname: Pilařová
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem, Czech Republic.
authors.forename: Luboš
authors.initials: L
authors.lastname: Vrtoch
authors.affiliation: Faculty of Sciences, University of Jan Evangelista Purkyně, České Mládeže 8, 400 96 Ústí nad Labem, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Kormunda
authors.affiliation: Military Research Institute, Veslařská 230, 637 00 Brno, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Mazanec
authors.affiliation: Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Štengl
keywords: Cerium oxide; Chemical warfare agents; Decontamination; Organophosphate compounds