Cerium dioxide as a new reactive sorbent for fast degradation of parathion methyl and some other organophosphates

0429174 - ÚACH 2015 RIV CN eng J - Článek v odborném periodiku
Janos, P. - Kuráň, P. - Kormunda, M. - Štengl, Václav - Matys Grygar, Tomáš - Došek, M. - Šťastný, M. - Ederer, J. - Pilařová, V. - Vrtoch, L.
Cerium dioxide as a new reactive sorbent for fast degradation of parathion methyl and some other organophosphates.
Journal of Rare Earths. Roč. 32, č. 4 (2014), s. 360-370. ISSN 1002-0721. E-ISSN 1002-0721
Institucionální podpora: RVO:61388980
Klíčová slova: cerium dioxide * carbonate precursor * lanthanides * organophosphate pesticide * parathion methyl * chemical warfare agents
Kód oboru RIV: CA - Anorganická chemie
Impakt faktor: 1.261, rok: 2014

Cerium dioxide was used for the first time as reactive sorbent for the degradation of the organophosphate pesticides parathion methyl, chlorpyrifos, dichlofenthion, fenchlorphos, and prothiofos, as well as of some chemical warfare agents-nerve gases soman and O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX). CeO2 specimens were prepared by calcination of basic cerous carbonate obtained by precipitation from an aqueous solution. The CeO2 samples containing certain amounts (1 wt.%-5 wt.%) of the neighboring lanthanides (La, Pr, Nd) were prepared in a similar way from pure lanthanide salts. It was shown that ceria accelerated markedly the decomposition of parathion methyl causing the cleavage of the P-O-aryl bond in the pesticide molecule. A similar reaction mechanism was proposed for the degradation of other organophosphate pesticides and nerve agents. The degradation times (reaction half-times) were in an order of minutes in the presence of CeO2, compared to hours or days under common environmental conditions. The reaction in suitable organic solvents allowed conversions of about 90% for parathion methyl loading of 20 mg pesticide/g CeO2 within 2 h with a reactant half-life in the order of 0.1 min. The key parameter governing the degradation efficiency of CeO2 was the temperature during calcination. At optimum calcination temperature (about 773.15 K), the produced ceria retained a sufficiently high surface area, and attained an optimum degree of crystallinity (related to a number of crystal defects, and thus potential reactive sites). The presence of other lanthanides somewhat decreased the reaction rate, but this effect was not detrimental and permitted the possible use of chemically impure ceria as a reactive sorbent. A fast organophosphate degradation was demonstrated not only in non-polar solvents (such as heptane), but also in polar aprotic solvents (acetonitrile, acetone) that are miscible with water.
Trvalý link: http://hdl.handle.net/11104/0234320