1. Teflon Vials For Precise C-14 in Benzene Measurements by LSC Technique

    Vadim V. Skripkin1, Mykhailo G. Buzynnyi2

    1. Institute of Environmental Geochemistry NAS of Ukraine, 34a Palladin ave., 03680, Kyiv, Ukraine.
    2. The O. M. Marzeev Institute of Public Health NAMS of Ukraine, 50, Popudrenko str., 02094, Kyiv, Ukraine.

    Abstract: We had developed and well tested vials in which Teflon and titanium where used as only materials. We avoid other material thinking about benzene sorption. We control counting efficiency avoiding presence of any “dead zone” inside. Vial flask and cap are spline coupled, both produced of Teflon. Other parts are of metal: stand, washer and valve. Vial volume ranges of: 0.8, 1.5, 2.5, 4.0 and 7.0 ml. Vials have extreme durability, low benzene leakage, high counting efficiency and low background. Benzene leakage is below 0.1% for one months of storage for series of vials.

    Keywords: C-14, LSC, Teflon vial, titanium, extreme durability, low benzene leakage.

    Pages: 229 – 233 | Full PDF Paper
  2. CH4 and CO2 Adsorption Study in ZIF-8 and Al-BDC MOFs

    Autié Castro G.1, de Oliveira Jardim E.2, Reguera E.1,3, Vilarrasa-García E.2, Rodríguez-Castellón E.4*, Cavalcante Jr. C.L.2

    1.Institute of Science and Technology of Materials (IMRE), University of Havana, 10400 Havana, Cuba.
    2.Universidade Federal do Ceará, Department of Chemical Engineering, GPSA-Group of Research in Separations by Adsorption, Campus do Pici, 60455760 Fortaleza, Ceará, Brazil.
    3. Center for Applied Science and Advanced Technologies of IPN, 11500, Mexico, DF.
    4. Department of Inorganic Chemistry, Crystallography and Mineralogy, Faculty of Sciences, University of Malaga, Campus de Teatinos, 29071, Malaga, Spain.

    Abstract: CH4 and CO2 adsorption capacity at 25, 50 and 75°C was evaluated in two metal-organic frameworks: Al-BDC and ZIF-8, the later with zeolite topology. Adsorption experiments were carried out under static conditions using a gravimetric suspension balance until 40 bar of pressure. Adsorption isotherms of type I were obtained for both materials showing high adsorption capacity values. ZIF-8 exhibited the higher uptake value for both CH4 and CO2 (4.9 and 8.5 mmol g-1, respectively). The Toth equilibrium model was used to fit experimental isotherms in order to obtain qm (maximum adsorption capacity) and t (related to energetical heterogeneity of the surface). Isosteric heats of adsorption were also calculated by Clausius-Clapeyron equation.

    Keywords: Adsorption, ZIFs, MOFs, adsorption heats, adsorption isotherm.

    Pages: 234 – 246 | Full PDF Paper