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Interaction of methoxy- and methylenedioxyamphetamines with carbon and polymeric adsorbents in polar liquids

100%
Tomaszewski W., Gun’ko V., Leboda R., Skubiszewska-Zięba J.
Open Chemistry
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2010
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vol. 8
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issue 4
750-757
EN
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. [...]
2
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The study of cyclooctene oxidation with molecular oxygen catalyzed by VSi2

100%
Makota O., Trach Y., Leboda R., Skubiszewska-Zięba J.
Open Chemistry
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2009
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vol. 7
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issue 4
731-738
EN
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. [...]
3
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Physical-chemical transformations in the system V2O5/(NH4)2Mo2O7 under hydrothermal conditions

88%
Khalameida S., Sydorchuk V., Leboda R., Skubiszewska-Zięba J., Zazhigalov V.
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issue 2
140-152
EN
Modified compositions in the system V2O5/(NH4)2Mo2O7 have been prepared by means of mechanochemical, hydrothermal, microwave and ultrasonic treatments in aqueous medium. Chemical and phase transformations occurring on the stages of modification and following calcinations have been studied with the help of XRD, DTA-TG, FTIR and UV-Vis spectroscopy, nitrogen adsorption, and SEM. It has been established that precursors of catalytically active phases possessing meso-macroporous structure have been formed during modification. The comparison of the properties of compositions prepared via different methods has been carried out. Particularly, precursors modified via various procedures possess different morphology.
4
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A role of free silanol groups of nanosilica surface in interaction with poly(vinyl pyrrolidone)

76%
Voronina O., Malysheva M., Nosach L., Voronin E., Gun’ko V., Charmas B., Skubiszewska-Zięba J.
Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia
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2017
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vol. 72
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issue 2
EN
In this work, a role of the number of free silanol groups at a nanosilica surface (specific surface area SBET = 250 m2/g, initial amount of silanols αОН = 0.60-0.62 mmol/g) was analyzed in interaction with poly(vinyl pyrrolidone) (PVP) vs. the degree (QTMS) of silica hydrophobization by hexamethyldisilazane at 100 oC. The value of QTMS was 0.07, 0.42, 0.67, 0.81, 0.82, and 1.0. Adsorption of PVP onto a nanosilica surface was carried out from a water and water-ethanol (1:1) solutions of the polymer. It was shown that free silanol groups play a crucial role in the adsorption of poly(vinyl pyrrolidone). The value of the maximal adsorption (monolayer capacity) on completely hydrophobic nanosilica surface is approximately by 6.5 times lower than that for unmodified nanosilica
5
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Electokinetic and adsorption properties of different titanium dioxides at the solid/solution interface

76%
Khalameida S., Skwarek E., Janusz W., Sydorchuk V., Leboda R., Skubiszewska-Zięba J.
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issue 11
1194-1205
EN
Six samples of titanium dioxide of different phase compositions and specific surface areas have been characterized by XRD, Raman-and FTIR spectroscopy, adsorption of nitrogen, electrophoresis. Adsorption of Zn(II) ions at the TiO2/NaCl aqueous solution interface as well as the effect of adsorption on the structure of electrical double layer have been studied. The influence of ionic strength, pH and presence of ions on the adsorption of Zn(II) ions at the TiO2/NaCl solution interface have also been investigated. The zeta potential, surface charge density, parameters of adsorption edge pH50% and ΔpH10–90% for different concentrations of basic electrolyte have been determined. Studied unpurified samples showed lower values of isoelectric point pHiep compared with literature data due to the presence of anion impurities. The antibate dependence between pHiep values and particle size has been established. Adsorption of Zn(II) ions using monophase samples is completed at a lower pH than for the biphase TiO2. Appearance of the point CR3 is associated with the charge turnover from positive to negative at high values of pH and formation of Zn(OH)2.
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