Yazar "Yurdakoç, M" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • [ X ]
    Öğe
    Acidity of silica-alumina catalysts by amine titration using Hammett indicators and FT-IR study of pyridine adsorption
    (Scientific Technical Research Council Turkey, 1999) Yurdakoç, M; Akçay, M; Tonbul, Y; Yurdakoç, K
    In this study, characterization and surface acidity of Siral (SiO2-Al2O3) compounds were investigated with Hammett acidity functions, the n-butylamine titration method and FTIR analysis of the spectra of pyridine adsorption. All the samples had an acid strength of H-0 less than or equal to +2.8. The calculated total amount of acid of the samples increased with the increase in SiO2 content up to Siral 40 and then decreased sharply in the case of Siral 80. Maximum amount of acidity was observed in the case of Siral 40 as 1.37mmole/g. No evidence was found for a band at 1540 cm(-1) on Pural indicating that there were no Bronsted sites on the surface strong enough to react with pyridine. As a result, we can say that the Lewis sites predominate in all the silica-aluminas.
  • [ X ]
    Öğe
    Effect of long-chain amines on the extraction of boron from CaCl2 brine with CTMP in petroleum benzine
    (Marcel Dekker Inc, 1999) Yurdakoç, M; Karakaplan, M; Hosgören, H
    The effect of TOA (tri-n-octylamine), TOMA (tri-n-octylmethylammonium iodide), DEDA (N,N'-didodecylethylenediamine), DEDMA (N,N'-didodecyl-N,N'-tetramethylethylene-diammonium diiodide), and NDM (N-dodecylmorpholine) upon the solvent extraction of boron from CaCl2 brine with CTMP [2-chloro-4(1,1,3,3,-tetramethylbutyl)-6-methylolphenol] in petroleum benzine has been studied. In order to extract boron effectively and reject other cations such as Ca2+, the extraction of boron with CTMP was investigated in terms of extractant, the concentration of an amine, and solvent polarity. The results show that in the presence of long-chain amines, boron extraction with CTMP in all solvent systems was shifted To a more acidic pH range. Larger extraction, hence distribution, and an increase in selectivity are observed when CTMP is used together with long-chain amines and their ammonium salts in petroleum benzine.
  • [ X ]
    Öğe
    FTIR study of the adsorption of ammonia and pyridine on V2O5/MgO catalysts
    (Marcel Dekker Inc, 1998) Akçay, M; Yurdakoç, M; Tonbul, Y; Yurdakoç, K; Hönicke, D
    The adsorption of ammonia and pyridine on the surface of the V2O5/MgO catalysts has been studied for the determination of the Bronsted and Lewis acid sites. The data showed that the catalysts have medium Lewis acidity, but are also weak Bronsted acids, having active hydroxy groups able to interact with pyridine by H-bonding and by protonation. Pyridine is a suitable basic probe for the quantification of the catalysts. 32% V2O5/MgO catalyst is the most acidic catalyst.
  • [ X ]
    Öğe
    Influence of transition metal ions on NMR proton T1 relaxation times of serum, blood, and red cells
    (Humana Press Inc, 1999) Yilmaz, A; Yurdakoç, M; Isik, B
    The spin-lattice relaxation rates (1/T1) of serum, whole blood, and red cells were measured vs several concentrations of transition metal ions. For comparative purposes, the similar experiments were repeated in water. The rates show a linear dependence on concentration of each ion for water, but nearly a linear dependence for blood and its constituents. The influence of each ion on 1/T1 in a sample was expressed by the slope (relaxivity) of the least-squares fitting of 1/T1 vs ion concentration. The relaxivities of Mn(II) in serum and of Fe(III) in serum and blood are greater than those in water, whereas the relaxivities of these ions in the other cases and of all the other ions in call cases are smaller than those in water. However, the relaxivity data show that Cr(III) in serum and blood affects the 1/T1 rates. The ratio of relaxivity of each sample to that of water is known as proton relaxation enhancement (PRR) factor (epsilon). The epsilon factors for present data suggest that the added ions are bound to proteins, and only Mn(II) in serum and Fe(III) in blood and serum are accessible to water.