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Pontifícia Universidade Católica do Rio de Janeiro

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Professor Volodymyr Zaitsev

Professor, D.Sc., PhD, Corr. Member Acad. of Sci. of Ukraine

 Zaitsev
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2007

  1. Alekseev, S.A., Lysenko, V., Zaitsev, V.N., Barbier, D. Application of infrared interferometry for quantitative analysis of chemical groups grafted onto the internal surface of porous silicon nanostructures
    (2007) Journal of Physical Chemistry C, 111 (42), pp. 15217-15222.
    The internal surface of porous silicon (PS) nanostructures was chemically modified by octadecyl and carboxylic acid groups by applying the hydrosilylation reaction as well as by aminopropyl and vinyl groups applying the silanization reaction. Concentrations of the chemically grafted groups and thicknesses of grafted layers were determined by measurements of PS refractive index in the infrared spectral range. The Landau-Lifshitz-Looyenga effective media model was used to relate the measured refractive index values to a volume fraction and then to the concentration of the grafted groups. The described quantitative method was applied to determine the sensitivity limits of PS-based sensing devices.
  2. Méry, E., Alekseev, S.A., Zaitsev, V.N., Barbier, D.
    Covalent grafting of ion-exchanging groups on porous silicon for microsystem applications
    (2007) Sensors and Actuators, B: Chemical, 126 (1), pp. 120-125.
    We report the chemical functionalization of porous silicon (PS) by trimethylammoniumpropyl bromide (-(CH2)3N(CH3)3+B r-) and alkylsulfonic acid (-CxH2xSO3H) groups for microsystem components. PS was prepared by electrochemical etching of a p-type silicon wafer. Samples of PS were first thermally oxidized at 300 °C and densified at 500 or 700 °C under an inert atmosphere. Mercaptopropyl and trimethylammoniumpropyl bromide groups were grafted on the PS surface via a silanization procedure. The oxidation of mercapto groups was used for the synthesis of -CxH2xSO3H groups. The samples were studied by Fourier transform infrared spectroscopy (FT-IR) and temperature-programmed desorption mass spectrometry (TPD-MS). The grafting of -CxH2xSO3H groups was found to be dependent on the densification treatment of the oxide layer formed at the surface of PS crystallites by low temperature oxidation. For PS samples thermally oxidized at 300 °C, -CxH2xSO3H were not grafted, whereas for PS samples oxidized and densified at 500 or 700 °C, they were successfully grafted. In opposite, the densification treatment of PS samples has no significant influence on the grafting of -(CH2)3N(CH3)3+Br - groups.
  3. Kovalchuk, T., Sfihi, H.b c , Zaitsev, V.a , Fraissard, J.d e
    Recyclable solid catalysts for epoxidation of alkenes: Amino- and oniumsilica-immobilized [HPO4{W2O2(μ-O2)2(O2)2}]2- anion (2007) 
    Journal of Catalysis    , 249 (1), pp. 1-14.
    We designed solid catalysts for liquid-phase epoxidation based on functionalized silica {triple bond, long}Si(CH2)3Q+ [Q: {single bond}NH3, {single bond}NEt3, {single bond}NC5H5, {single bond}PPh3] and [HPO4{W2O2(μ-O2)2(O2)2}]2-. The approach that we adopted allowed us to avoid the use of chlorocarbon solvent and enabled catalyst recycling. By using supports with 4 different linking chains between the anion and silica and different surface lipophilicities, we followed their influence on catalyst activity in the epoxidation of cyclooctene and (R)-limonene by H2O2 in t-BuOH. All solids were active in cyclooctene epoxidation (conversion up to 100%; epoxide selectivity 100%; TOF 2-4 h-1 anion-1). The degree of surface coverage by organic functions was crucial for recycling performance. Catalysts with low densities of organic functions and hydrophilic surfaces were easily deactivated. End-capping improved their stability but decreased their activity. Catalysts with dense coverage of onium groups and the active site in a hydrophobic chloropropyl environment demonstrated high activity and excellent recycling stability. Less promising results were obtained in the epoxidation of (R)-limonene.
  4. I., Piquemal, J.-Y.a , Briot, E.c , Vaulay, M.-J.a , Connan, C.a , Truong, S.a , Zaitsev, V.b , Bozon-Verduraz, F.a
    The use of low-nuclearity oxoperoxo molybdenum species to achieve high dispersions on zirconia materials
    (2007) Applied Catalysis A: General, 325 (1), pp. 140-153.
    Molybdenum(VI) species have been deposited on zirconia materials by adsorption equilibrium procedures using two precursors: (i) an isopolyanion salt: ammonium heptamolybdate and (ii) low-nuclearity oxoperoxo molybdenum complexes. Two zirconia supports have been considered: calcined zirconia (ZrO2) and the parent zirconium oxyhydroxide (ZrOx(OH)4-2x). After drying, the catalysts have been calcined and characterized by chemical analysis, powder X-ray diffraction, thermogravimetry, Raman and UV-vis diffuse reflectance spectroscopies, X-ray photoelectron spectroscopy, nitrogen physisorption experiments, and TEM and EDX analysis. In contrast to ZrO2, quantitative grafting of molybdenum species can be obtained when zirconium oxyhydroxide is used. With this material, the anchoring of low-nuclearity oxoperoxo species leads to higher specific surface areas than with ammonium heptamolybdate, and hence to lower molybdenum surface densities.
  5. Alekseev, S.A., Zaitsev, V.N., Botsoa, J., Barbier, D.
    Fourier transform infrared spectroscopy and temperature-programmed desorption mass spectrometry study of surface chemistry of porous 6H-SiC.
    (2007) Chemistry of Materials, 19 (9), pp. 2189-2194.
    Porous SiC (PSC) freestanding layers were prepared via UV light-assisted electrochemical etching of an n-type 6H-SiC wafer. Fourier transform infrared (FTIR) spectroscopy and temperature-programmed desorption mass spectrometry (TPD-MS) were applied to characterize functional groups on the PSC surface and their chemical reactivity. It was shown that as-prepared PSC contains silanol groups, carboxylic acid groups, minor amounts of SiH and CHx groups, and also a carbon-rich surface phase. Annealing of PSC in air at 673 K resulted in the oxidation of the carbon-containing surface species and the formation of a hydrated silicon oxide surface layer. Using -Si(CH3)3 groups as a model, it was demonstrated that organic functional groups can easily be grafted on oxidized PSC via common silanization chemistry. Treatment of oxidized PSC with HF resulted in the formation of a surface terminated with methyl groups. It confirms that the walls of the PSC pores are constituted of the (0001) "silicon" crystal face of SiC and faces with similar atomic structure.
  6. Chapron, J., Alekseev, S.A., Lysenko, V., Zaitsev, V.N., Barbier, D.
    Analysis of interaction between chemical agents and porous Si nanostructures using optical sensing properties of infra-red Rugate filters
    (2007) Sensors and Actuators, B: Chemical, 120 (2), pp. 706-711.
    Porous silicon based optical Rugate filters operating in the infra-red spectral range have been used to study chemical modifications (alkylation and oxidation) of the porous silicon internal specific surface. Influences of the chemical modifications on the filter response and on its sensitivity for solvent detection is described in details. Important quantitative information concerning structure and chemical coating of the filters is obtained. Application of the porous filters for the detection of different solvents filling their nanopores is studied. © 2006 Elsevier B.V. All rights reserved.
  7. В.М. Брицун, В.О. Дорощук, Н.В. Богдан,  В.М. Зайцев, М.О. Лозинський
    ДОСЛІДЖЕННЯ КИСЛОТНОСТІ  ТІОАМІДІВ, ЯКІ МІСТЯТЬ АКТИВНУ МЕТИЛЕНОВУ ГРУПУ.
    Укр. хим. журн., 2007, т.73, №5, с.40-43.
    Методом pH-метричного титрування в суміші ДМСО-Н2О (1:1) і розрахунку за допомогою програми ACDLAB 4.0 були досліджені конс­тан­ти кислотності тіоамідів, що містять активну метиленову групу.
  8. О.П.Конопліцька, В.М.Зайцев, Г.М.Зайцева. Сорбційно-атомно-абсорбційне визначення срібла у воді. Методы и объекты химического анализа, 2007, т.2, №1, с. 56-62.
    Изучены оптимальные условия сорбции ионов серебра на кремнеземе с ковалентно закрепленными группами пропилтиоетиламина. Предложена сорбционно-атомно-абсорбцыонная методика определения Ag(I) в природных водах. Методика позволяет определять ионы серебра в концентрациях на уровне и ниже ПДК без отделения от матрицы.
  9. Зайцева,Г., Конопліцька,О., Зайцев,В
    Сорбційно-твердофазно-фотометричне визначення ртуті на пропілтіо етиламінокремнеземі
    Вісник КНУ ім.Т. Шевченка (2007), 45 (24-26)
    Для селективного вилучення іонів ртуті із водних розчинів запропоновано адсорбент на основі кремнезему, модифікованого пропілтіо- етиламіном. Вивчено оптимальні умови сорбції Hg (II) на поверхні модифі- кованого кремнезему з розчинів і розроблено сорбційно-твердофазно-фотометричну методику для визнчення 0,25-2,5мкг/мл іонів ртуті
  10. Зайцев,В.,Трохименко,О., Самусева,В.
    Іонообмінні характеристики етилсульфокремнезему
    Вісник КНУ ім.Т. Шевченка (2007), 45 (18-20)
    Визначено динамічні іонообмінні характеристики кремнезему з ковалентно закріпленими етилсульфокислотними групами. Установлено, що даний іоніт проявляе властивості сильнокислотного катіоніту, що сорбує метали за електростатичним механізмом
  11. Лисенко,О., Зайцев,В., Мірза,Н.
    Сорбційно-десорбційно-фотометричне визначення мікрокількостей феруму в сульфосаліциловій кислоті з викристанням 3-(метиламоній)-пропілкремнезему
    Вісник КНУ ім.Т. Шевченка (2007), 45 (27-28)
    Вивчено вплив концентрації сульфосаліцилат-, сульфат- і хлорид іонів на повноту сорбції сульфосаліцилатних комплексів феруму (III. Розроблено “безреагентний” метод визначення мікрокількостей феруму (III) в сульфосаліциловій кислоті, який полягає в селективному вилученні сульфосаліцилатних комплексів Fe(III) 3-(метиламоній)-пропілкремнеземом при pH 5-8, елююванні комплексів 0,20 М нітратною кислотою і вимірюванні оптичної густини елюатів після додавання амоніаку. Інтевал визначуваних кількостей феруму 1,7-20 мкг у наважці кислоти 0,5-0,6 г. Нижня межа визначуваного вмісту становить 2,8*10-4 %, стандартне відхилення 8,1% (=3 P=0.95).

Laboratório de adsorventes para análise química, proteção de ambiente e biomedicina (LAQAPAB)
Departamento de Química,  Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio)
tel: +55 21 980551969,
e-mail: vnzaitsev@puc-rio.br,
http://zaitsev.usuarios.rdc.puc-rio.br

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