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  • Author or Editor: J. Goworek x
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Abstract  

Thermogravimetric analysis was applied to the characterization of the porosity of silica gels. Results from thermogravimetric method are compared with those obtained from the nitrogen method. The consistency of the parameters characterizing the porous structure of silica gels derived from the data of various methods is satisfactory.

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Abstract  

Magnetic quenching experiments with naphthalene give small value of density parameter . Corresponding lifetime of p-Ps should be equal or close to that of free annihilation. Contrary to expectations, we obtained the lifetime of short-lived component 1=180ps (its intensity is larger than predicted by statistical weight rule). Generally, the experiments with the use of magnetic field give smaller value than these using zero-field methods.

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Abstract  

Mesoporous materials MCM-41 with the hexagonal arrangement of pores were obtained using dodecyltrimethylammonium bromide and octadecyltrimethylammonium bromide as templating surfactants. Adsorption of toluene and propan-1-ol on the as-synthesized MCM-41 silica samples was investigated using the TG-DTG, DTA and DSC techniques. The sorption mechanism of used adsorptives is discussed in terms of hydrophobicity of pore interior filled with template as well as pore dimensions.

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Abstract  

Mesoporous silica material of MCM-41 type was synthesized by co-condensation of highly concentrated octyltriethoxysilane (OTEOS), octadecyltriethoxysilane (ODTEOS) and tetraethoxysilane (TEOS). The obtained hybrid materials were characterized using XRD, TG-DSC and low temperature adsorption/desorption of nitrogen. It was shown that the applied method of synthesis allows to obtain silica of MCM-41 type with a high degree of hydrocarbon saturation.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
T. Goworek
,
B. Jasińska
,
J. Wawryszczuk
, and
K. Ciesielski

Abstract  

Temperature dependence of positronium formation probabilityP was measured for catechol, resorcinol and hydroquinone. The variations ofP with temperature and relative permittivity can be explained in the framework of spur reaction mode. It seems that the spur processes are important at the first stage of Ps formation, the final value ofP depends also on free volume availability and trapping efficiency.

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Abstract  

Thermal evacuation of a surfactant template from pure siliceous MCM-41 and MCM-41 containing aluminium in hydrogen flow was investigated. Micelle templated MCM-41 were prepared using hexadecyltrimethylammonium bromide (CTAB). The products of thermal surfactant degradation outside and inside pores were identified at various temperatures using 13C solid-state nuclear magnetic resonance (NMR) spectroscopy, gas chromatography coupled with mass spectrometer (GC-MS) and temperature programmed desorption coupled with mass spectrometer (TPD-MS). The GC-MS and 13C MAS NMR results obtained from this study provide an insight into the mechanism of surfactant transformation during MCM-41 synthesis on molecular level.

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Journal of Thermal Analysis and Calorimetry
Authors:
A. Dąbrowski
,
E. Mendyk
,
E. Robens
,
K. Skrzypiec
,
J. Goworek
,
Mariola Iwan
, and
Zofia Rzączyńska

Abstract  

We investigated lunar regolith collected during the Apollo 11, 12 and the Apollo 16 missions. The Apollo 11 and the Apollo 12 samples come from the lunar mare, whereas the Apollo 16 expedition brought back material from a highland region of the near side of the Moon. In paper series we summarise in brief the results of measurements using photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), nitrogen adsorption, thermal analysis (TG, DTA) and temperature-programmed reduction and oxidation (TPRO) method. Parts of samples were examined by means of scanning electron (SEM/EDS) and atomic force microscopy (AFM).

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