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

Journal of Rare Earths 2014年第4期32卷 360-370页

作者： Pavel Janos Pavel Kuran martin Kormunda Vaclav Stengl Tomas Matys Grygar Marek Dosek martin stastny Jakub Ederer Vera Pilarova Lubos Vrtoch Faculty of the Environment University of Jan Evangelista Purkyne Faculty of Science University of Jan Evangelista Purkyne Institute of Inorganic Chemistry AS CR v.v.i.

Cerium dioxide was used for the first time as reactive sorbent for the degradation of the organophosphate pesticides para-thion 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 environ-mental 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 poten-tial 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. This opens new possibilities for designi

关键词： cerium dioxide carbonate precursor lanthanides organophosphate pesticide parathion methyl chemical warfare agents hydrolysis non-aqueous solvents rare earths

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Determining the Relative Age of Fault Activity through Analyses of Gouge Mineralogy and Geochemistry: A Case Study from Vápenná(Rychleby Mts), Czech Republic

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International Journal of Geosciences 2010年第2期1卷 66-69页

作者： Lucie Nováková Pavel Hájek martin stastny 不详

The relative age of fractures can be determined through structural analyses in the field or through the detailed mineralogical (XRD) and chemical analyses (AAS method, volumetric, and gravimetric analysis) of fault gouge in the laboratory. The aim of this work was to compare these approaches. It was hypothesised that the two methods would yield consistent results. The studied faults were located in the Rychleby Mts, part of the Sudetic Marginal Fault Zone. The relative age of the faults was determined in the field through the application of the intersection law. The fault gouges were sampled in a crystalline limestone quarry near the village of Vápenná. The mineralogical composition of the fault gouges has been established by XRD analysis of powder samples and analysis of preferentially oriented clay minerals. From our result, it is clear that these two approaches yielded consistent results with regard to the relative age of the faults.

关键词： Crystalline Limestone Intersecting Faults Fault Gouge Relative Chronology

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