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Gun'ko VM Blitz JP Zarko VI Turov VV Pakhlov EM Oranska OI Goncharuk EV Gornikov YI Sergeev VS Kulik TV Palyanytsya BB Samala RK 《Journal of colloid and interface science》2009,330(1):125-137
Morphological, structural, adsorption, and catalytic properties of highly disperse titania prepared using sulfate and pyrogenic methods, and fumed titania-containing mixed oxides, were studied using XRD, TG/DTA, nitrogen adsorption, (1)H NMR, FTIR, microcalorimetry on immersion of oxides in water and decane, thermally stimulated depolarization current (TSDC) and catalytic photodecomposition of methylene blue (MB). Phase composition and aggregation characteristics of nanoparticles (pore size distribution) of sulfate and pyrogenically prepared titania are very different; temperature dependent structural properties are thus very different. Catalytic activity for the photodecomposition of MB is greatest (per gram of TiO(2) for the pure oxide materials) for non-treated ultrafine titania PC-500, which has the largest S(BET) value and smallest particle size of the materials studied. However, this activity calculated per m(2) is higher for PC-105, possessing a much smaller S(BET) value than PC-500. The activity per unit surface area of titania is greatest for the fumed silica-titania mixed oxide ST20. Calcination of PC-500 at 650 degrees C leads to enhancement of anatase content and catalytic activity, but heating at 800 and 900 degrees C lowers the anatase content (since rutile appears) and diminishes catalytic activity, as well as the specific surface area because of nanoparticle sintering. 相似文献
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Kostiantyn Kulyk Valentyna Ishchenko Borys Palyanytsya Volodymyr Khylya Mykola Borysenko Tetiana Kulyk 《Journal of mass spectrometry : JMS》2010,45(7):750-761
The interactions between coumarins and the surface of fumed SiO2, CeO2/SiO2, TiO2/SiO2 and Al2O3/SiO2 were assessed by means of temperature‐programed desorption mass spectrometry. The different stages of the thermolysis of coumarin were identified and an analysis of the underlying reactions was performed. The kinetic parameters of the involved reactions were thus obtained. The decomposition of thiazolyl‐substituted coumarins was found to proceed through a ‘thiazole–thiazine’ ring expansion in the adsorbed state. A linear correlation between the sigma constants (Σσ) of the coumarin substituents and the activation energy of CO2 formation was obtained. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Structural features of polymer adsorbent LiChrolut EN and interfacial behavior of water and water/organic mixtures 总被引:1,自引:0,他引:1
Gun'ko VM Turov VV Zarko VI Nychiporuk YM Goncharuk EV Pakhlov EM Yurchenko GR Kulik TV Palyanytsya BB Borodavka TV Krupskaya TV Leboda R Skubiszewska-Zieba J Osovskii VD Ptushinskii YG Turov AV 《Journal of colloid and interface science》2008,323(1):6-17
The structural and adsorption characteristics of polymer adsorbent LiChrolut EN and the behavior of adsorbed water and water/organic mixtures were studied using adsorption, microcalorimetry, transmission and scanning electron microscopy, mass spectrometry, infrared spectroscopy, 1H NMR spectroscopy with layer-by-layer freezing-out of liquids (190-273 K), and thermally stimulated depolarization current method (90-265 K). This adsorbent is characterized by large specific surface area (approximately 1500 m2/g) and pore volume (0.83 cm3/g) with a major contribution of narrow pores (R<10 nm) of a complicated shape (long hysteresis loop is in nitrogen adsorption-desorption isotherm). The adsorbent includes aromatic and aliphatic structures and oxygen-containing functionalities and can effectively adsorb organics and water/organic mixtures. On co-adsorption of water and organics (dimethyl sulfoxide, chloroform, methane), there is a weak influence of one on another adsorbate due to their poor mixing in pores. Weakly polar chloroform displaces a fraction of water from narrow pores. These effects can explain high efficiency of the adsorbent in solid-phase extraction of organics from aqueous solutions. The influence of structural features of several carbon and polymer adsorbents on adsorbed nitrogen, water and water/organics is compared on the basis of the adsorption and 1H NMR data. 相似文献
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T. V. Borodavka T. V. Kulik B. B. Palyanytsya 《Journal of Analytical Chemistry》2010,65(13):1377-1381
Curves representing the dependence of the pressure of volatile products formed in the destruction of chitin or chitosan on
the thermolysis temperature were analyzed. The curves were obtained using temperature programmed desorption mass spectrometry.
It was shown that the shape and positions of the maxima in the curves depend on the ratio of the numbers of pyranose rings
bearing amine and acetamide groups in the polymer chain. A new approach was proposed for determining the deacetylation degree
of chitin or chitosan based on the data of temperature programmed desorption mass spectrometry. 相似文献
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T.V. Kulik N.A. Lipkovska V.N. Barvinchenko B.B. Palyanytsya O.A. Kazakova O.A. Dovbiy V.K. Pogorelyi 《Journal of colloid and interface science》2009,339(1):60-68
The interactions of bioactive ferulic acid with fumed silica were studied by UV/vis spectroscopy, FT-IR, TPD MS techniques and quantum chemical methods. It was found that surface complexes may form through phenol or carboxyl group of ferulic acid depending on its coverage value. The structure of surface complexes and mechanisms of the ferulic acid chemosorption on the silica surface are discussed. The kinetic parameters of the chemical reactions on silica surface are calculated. The mechanisms of thermal transformations of the ferulic chemosorbed surface complexes are proposed. 相似文献
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Gun'ko VM Mironyuk IF Zarko VI Voronin EF Turov VV Pakhlov EM Goncharuk EV Nychiporuk YM Vlasova NN Gorbik PP Mishchuk OA Chuiko AA Kulik TV Palyanytsya BB Pakhovchishin SV Skubiszewska-Zieba J Janusz W Turov AV Leboda R 《Journal of colloid and interface science》2005,289(2):427-445
Several series of fumed silicas and mixed fumed oxides produced and treated under different conditions were studied in gaseous and liquid media using nitrogen and water adsorption-desorption, mass spectrometry, FTIR, NMR, thermally stimulated depolarization current (TSDC), photon correlation spectroscopy (PCS), zeta potential, potentiometric titration, and Auger electron spectroscopy methods. Aggregation of primary particles and adsorption capacity (Vp) decrease and hysteresis loops of nitrogen adsorption-desorption isotherms becomes shorter with decreasing specific surface area (S(BET)). However, the shape of nitrogen adsorption-desorption isotherms can be assigned to the same type independent of S(BET) value. The main maximum of pore size distribution (gaps between primary nonporous particles in aggregates and agglomerates) shifts toward larger pore size and its intensity decreases with decreasing S(BET) value. The water adsorption increases with increasing S(BET) value; however, the opposite effect is observed for the content of surface hydroxyls (in mmol/m2). Associative desorption of water (2(SiOH)-->SiOSi+H2O) depends on both the morphology and synthesis conditions of fumed silica. The silica dissolution rate increases with increasing S(BET) and pH values. However, surface charge density and the modulus of zeta-potential increase with decreasing S(BET) value. The PCS, 1H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the S(BET) value and the silica concentration (C(SiO2)) in the aqueous suspensions. A specific state of the dispersion is observed at the C(SiO2) values corresponding to the bulk density of the initial silica powder. 相似文献
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V.M. Gun’ko M.V. Borysenko A. Spanoudaki I.Y. Sulim B.B. Palyanytsya 《Applied Surface Science》2007,253(17):7143-7156
Polydimethylsiloxane (PDMS)/fumed silica A-300 and PDMS/ZrO2/A-300 were studied using adsorption, thermogravimetry, temperature-programmed desorption (TPD) mass-spectrometry, infrared spectroscopy, XRD, and broadband dielectric relaxation spectroscopy. ZrO2 was synthesized on fumed silica with zirconium acetylacetonate in CCl4 at 350 K for 1 h and calcinated at 773 K for 1 h (1-4 reaction cycles). PDMS (5-40 wt.%) was adsorbed onto silica and zirconia/silica from hexane solution and then dried. Grafted zirconia changes the chemistry of the surface (because of its catalytic capability) and the topology of secondary particles (because of occupation of voids in aggregates of primary silica particles by zirconia nanoparticles) responsible for the textural porosity of the powders. Therefore, many properties (such as structural characteristics of the composites, reactions on heating in air and vacuum, interfacial relaxation phenomena, hydrophobicity as a function of treatment temperature, etc.) of PDMS/zirconia/silica strongly differ from those of PDMS/A-300. Broadening of the α-relaxation of PDMS at the interfaces of disperse oxides suggests both weakening of the PDMS-PDMS interaction and strengthening of the PDMS-oxide interaction. 相似文献
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