排序方式: 共有44条查询结果,搜索用时 15 毫秒
1.
V. V. Sidorchuk J. Skubiszewska-Zięba S. V. Khalameida V. A. Zazhigalov R. Leboda 《Russian Journal of Applied Chemistry》2008,81(8):1325-1331
Effect of conditions of hydrothermal and microwave synthesis of supported vanadium-phosphorus oxide catalysts in an aqueous medium on the physicochemical properties of the vanadyl hydrophosphate obtained was studied. The transformations occurring in the system were examined using X-ray phase and differential-thermal analyses, adsorption-structural method, and scanning electron microscopy. 相似文献
2.
Pyrocarbon/silica gel adsorbents (carbosils, CS) with mesoporous Si-60 (Merck, granule size 0.2–0.5 mm) modified by pyrolysis of CH2Cl2 at 823 K and reaction time from 0.5 to 6 h and then hydrothermally treated at 473 K for 6 h were studied by means of TEM, adsorption and 1H NMR methods. Changes in the structural and adsorptive characteristics of hybrid adsorbents before and after hydrothermal treatment, which depend on pyrocarbon content (C
C), were analyzed on the basis of TEM micrographs and p-nitrophenol and nitrogen adsorption isotherms treated using a constrained regularization method. Interfacial water layers in aqueous suspension of CS were investigated by means of 1H NMR with freezing-out of bulk water at T < 273 K showing nonlinear changes in the Gibbs free energy of interfacial water with increasing C
C because of nonlinear dependence of the structural characteristics of pyrocarbon deposits and CS as a whole on C
C. 相似文献
3.
S. Khalameida V. Sydorchuk R. Leboda J. Skubiszewska-Zięba V. Zazhigalov 《Journal of Thermal Analysis and Calorimetry》2014,115(1):579-586
Interaction in the system of lithium carbonate–niobium pentoxide during mechanochemical treatment in air and water has been studied. Prepared samples have been investigated with the help of DTA–TG, XRD, FTIR, Raman, and UV–Vis spectroscopy, adsorption–desorption of nitrogen and TEM. Activation of reagents and direct mechanochemical synthesis are observed at 600–850 and 1,000 rpm, respectively. Lithium metaniobate samples prepared via milling possess high dispersity, defective structure, and improved photocatalytic activity, including under visible illumination. 相似文献
4.
V. Sydorchuk S. Khalameida V. Zazhigalov J. Skubiszewska-Zięba R. Leboda 《Journal of Thermal Analysis and Calorimetry》2010,100(1):11-17
Physicochemical processes during thermal treatment of vanadium and phosphorus oxides mixture (1) as well as with diammonium
hydrophosphate (2) in the closed system (autoclave) have been studied. In the first case, at 300 °C, the defective structure
γ-VOPO4 is formed and in the second case, there was established possibility of synthesis of vanadyl hydrophosphate—the precursor
of vanadyl pyrophosphate (the catalyst of n-butane oxidation to maleic anhydride). At the same time, various phases of mixed ammonium and vanadium phosphates were obtained
at lower and higher temperatures. 相似文献
5.
Waldemar Tomaszewski Vladimir M. Gun’ko Roman Leboda Jadwiga Skubiszewska-Zięba 《Central European Journal of Chemistry》2010,8(4):750-757
Solid phase extraction (SPE) of methoxy- and methylenedioxyamphetamines from diluted aqueous solutions was investigated on
carbon and polymeric adsorbents of different textures and chemical compositions. Those adsorbents were applied cartridges
packed with three chemically modified carbons prepared from plum stones (initial A2PS, oxidized A2PS-O, and reduced A2PS-H)
and commercially available adsorbents (polymeric LiChrolut EN, graphitized Hypercarb and Carboprep). Several factors influence
the recovery rates of amphetamine derivatives such as the polarity of adsorbates (free energy of salvation), the specific
surface area and surface composition of adsorbents, and the solvent characteristics. Different combinations of these factors
affect the recovery rate (R1) for high- and low-surface area adsorbents. The minimal R1 values are observed for an amphetamine
derivative at a maximal solvation effect and for a set of amphetamines adsorbed on graphitized carbons.
相似文献
6.
Oksana Makota Yuriy Trach Roman Leboda Jadwiga Skubiszewska-Zięba 《Central European Journal of Chemistry》2009,7(4):731-738
The catalytic effect of VSi2 on initial stages of the liquid-phase oxidation of cyclooctene by molecular oxygen was studied. The vanadium disilicide influences
on the oxidation process in the presence of hydroperoxide. VSi2 takes part in a radical formation stage by catalysis of hydroperoxide decomposition reaction. The catalyst was investigated
before and after reaction using FTIR spectroscopy. From the data obtained, the kinetic model of the catalytic oxidation process
was proposed and the equation for the reaction rate was derived. The equation has described all observed dependences of reaction
rate on the concentration of reactants and content of catalyst.
相似文献
7.
J. Skubiszewska-Zięba R. Leboda B. Charmas W Grzegorczyk R. Szmigielski 《Journal of Thermal Analysis and Calorimetry》2006,86(1):187-194
Thermal analysis was used to study thermal behavior of the sulfonated
ion exchange resin Duolite C20 in the hydrogen, sodium and calcium forms.
The aim of this paper was to prepare spherical carbon adsorbents. SEM and
AFM microscopic methods have been applied to describe their surface characteristics.
It was stated that structural parameters of prepared active carbons depend
on the kind of cation present in the resin. The use of calcium form of Duolite
C20 as the initial polymer precursor allowed to obtain the active carbon with
better yield and better developed pore structure compared with other forms
of this ion exchanger. 相似文献
8.
Jadwiga Skubiszewska-Zi?ba 《Applied Surface Science》2010,256(17):5520-5527
VPO catalysts were prepared on oxidized and unoxidized activated carbons differing in initial porous structure. Carbons were oxidized under relatively soft (30% H2O2, 200 °C) and hard (50% H2O2, 350 °C) conditions. Carbon modification was carried out hydrothermally in a traditional autoclave (HTT) or a microwave reactor (MWT). The synthesis was also carried out under hydrothermal (HTS or MWS) conditions. V2O5 and NH4VO3 were used as precursors. The samples are characterized by diversified porous structure at SBET = 732-1617 m2/g and Vpor = 0.44-0.90 cm3/g, as well as various degree of VPO crystallinity. Possibility of preparation of the VPO catalysts under ecologically appropriate conditions, i.e. in aqueous solutions, was shown. 相似文献
9.
Władysław Janusz Svetlana Khalameida Volodymyr Sydorchuk Ewa Skwarek Valery Zazhigalov Jadwiga Skubiszewska-Zięba Roman Leboda 《Adsorption》2010,16(4-5):333-341
Mechanochemical modification of vanadium phosphates doped with Bi, Zr, Mo has been studied. Milled samples have been investigated by means of XRD, DTA-TG, FTIR, nitrogen adsorption, electrokinetic measurements. It was found that phase composition of the phosphates does not change upon the mechanochemical modification process. Milling in water causes formation of porous materials. Modification of surface results in changes of the electrokinetic and adsorption properties of the milled samples. 相似文献
10.
E. Skwarek S. Khalameida W. Janusz V. Sydorchuk N. Konovalova V. Zazhigalov J. Skubiszewska-Zi?ba R. Leboda 《Journal of Thermal Analysis and Calorimetry》2011,106(3):881-894
Mechanochemical activation of individual V2O5, MoO3 and mixed vanadium-molybdenum oxide system in various media (air, water, and ethanol) has been studied. Powder X-ray diffraction, nitrogen adsorption?Cdesorption, thermogravimetric and chemical analysis, FTIR and Raman spectroscopy, and scanning electron microscopy have been used for research of prepared milled samples. The electrokinetic properties (dependence zeta potential??pH, position of isoelectric point) of individual V2O5, MoO3 and mixed vanadium?Cmolybdenum oxide system, synthesized via mechanochemical treatment in various medium, in aqueous solutions of electrolytes also have been determined. Initial, milled, and spent samples are characterized with the help of XRD, FTIR and Raman spectroscopy, and SEM and adsorption of nitrogen. The catalytic properties of vanadium?Cmolybdenum oxide composition activated in different media have been investigated in reaction of oxidation dehydrogenation of propane. 相似文献