Professor Vladimir Zaitsev

D.Sc., PhD, Corr. member of Acad. of Sci. of Ukraine

2004

1. Alekseev, S. A.; Zaitsev, V. N.; Alekseev, A. N.; Kochkin, Y. N.; Evans, J.
   Effect of silanol groups on the acidic and catalytic properties of alkylsulphoacidic silicas and SiO2/narion nanocomposites. Adsorption Science & Technology, 2004, 22 (8), 615-625.
   Sets of silicas covalently modified with alkylsulphoacidic groups (SiO2-SO3H) and nanocomposites of silica with superacidic Nafion® polymer (SiO2/Nafion) were synthesised. End-capping the silanol groups with trimethylsilyl groups was used to obtain surface hydrophobisation. The materials obtained were characterised by nitrogen and water adsorption measurements, MAS NMR spectroscopy and dielectric relaxation spectroscopy (DRS). The acidity of the materials was tested by 31P MAS NMR spectroscopic examination of samples with adsorbed triethylphosphine oxide (TEPO). It was demonstrated that endcapping excluded part of the surface silanol groups from interaction with acidic groups, thereby causing the sulphonic groups to exhibit an increased acidity. With SiO 2-SO3H, end-capping also increased their catalytic activity in the synthesis of ethyl t-butyl ether (ETBE). However, end-capping had a negligible effect on the catalytic properties of SiO2/Nafion, probably because the catalytic reaction occurred inside the Nafion polymer nanoparticles.
2. Zaitsev V.M. 55th Pittsburgh conference and exhibition on analytical chemistry (PITTCON 2004). Farmakom, 2004, 2, 5-9.

3. Trokhimenko, O.M., Zaitsev, V.N.
   Kinetic determination of iodide by the Sandell-Kolthoff reaction using diphenylamine-4-sulfonic acid (2004) Journal of Analytical Chemistry, 59 (5), pp. 491-494.
   The iodide-catalyzed reaction between arsenic(III) and cerium(IV) (Sandell-Kolthoff reaction) stopped by the addition of diphenylamine-4-sulfonic acid was used for the development of a sensitive kinetic procedure for determining iodides with a detection limit of 2 ng/mL. It was found that the developed procedure is suitable for the determination of total iodine in foodstuffs.

4. Puziy, A. M.; Poddubnaya, O. I.;Zaitsev, V. N.; Konoplitska, O. P., Modeling of heavy metal ion binding by phosphoric acid activated carbon. Applied Surface Science 2004, 221, (1-4), 421-429.
   The adsorption of heavy metal ions (Cu, Cd, Co and Pb) onto oxidized synthetic activated carbon SP800-Ox modified with phosphoric acid has been investigated. It has been shown that metal adsorption order depends on solution pH and metal ion concentration. Metal ion adsorption was modeled by the surface complexation model (DDL) where carbon is represented as four independent monoprotic acid sites (super-acidic, phosphorus-containing, carboxylic and phenolic). Initial estimation of the surface group density and acidity were made on the base of single ion binding data (proton binding) analysis by a continuous distribution approach. Calculated metal ion binding constants suggest formation of only monodentate charged complex with composition (≡SOMe+), where ≡SO- is deprotonated phosphoric, carboxylic or phenolic group. No other surface complexes were found to be significant. Super-acidic group did not participate in metal ion binding at all. © 2003 Elsevier B.V. All rights reserved.
5. Nadzhafova, O. Y.; Zaitsev, V. N.; Drozdova, M. V.; Vaze, A.; Rusling, J. F., Heme proteins sequestered in silica sol-gels using surfactants feature direct electron transfer and peroxidase activity. Electrochemistry Communications 2004, 6, (2), 205-209.
   Hemoglobin (Hb) and myoglobin (Mb) were incorporated into a porous silica network by a sol-gel method using tetraethoxysilane as precursor and cetyltrimethylammonium bromide (CTAB), poly(styrene sulfonate) (PSS) and Nafion as template additives. Three types of composite films were made on glass and pyrolytic graphite (PG) surfaces: silica-CTAB with Mb or Hb (SG-I); silica-CTAB-PSS with Mb (SG-II-Mb); and silica-CTAB-Nafion with Mb (SG-III-Mb). Cyclic voltammetry demonstrated that films with encapsulated protein exchange electrons directly with PG electrodes and have catalytic activity for reduction of oxygen and hydrogen peroxide. Surface areas studies suggest that CTAB can be removed selectively from the films. Catalytic efficiency of SG-I-Mb increased with increasing CTAB content in the initial sol. The SG-II-Mb film was more stable in aqueous propanol-CTAB and 2 mM hydrogen peroxide compared to SG-I-Mb (or Hb) and SG-III-Mb films. SG-II-Mb films on PG electrodes detected hydrogen peroxide by voltammetry with linear calibration in the range 2-30 μM, and detection limit 1.5 μM.
6. Kochetov, G.M., Ternovtsev, V.E., Zaitsev, V.N., Alekseev, S.A.
   Sorption-oxidizing method of purification for exhausted technological solutions (2004) Khimiya i Tekhnologiya Vody, 26 (5), pp. 444-449.
   The possibility of purification of concentrated industrial wastewater by sorption-oxidizing separation of impurities is proved. It is established, that addition of fine particle silica gel facilitates filtration of iron (III) hydroxide. The offered method for removal of Fe(II) from a solution is applied for selective purification of nickel-plating electrolyte.
7. Zajtsev, V.N., Reva, T.D., Zajtseva, G.N., Alekseev, S.A., Kalibabchuk, V.A.
   The 2,6-pyridinedicarboxylic acid covalently bonded to the silochrome surface: Immobilization and sorption-desorption properties (2004) Ukrainskij Khimicheskij Zhurnal, 70 (11-12), pp. 74-80.
   The method of 2,6-pyridine dicarbonic acid immobilization on the silica surface with a practically monofunctional nature of bonded layer has been proposed. The sorption of Cd2+, Zn2+, Cu2+, Ni2+, Fe2+, Fe3+ ions and the mechanism of their extraction by the solid-phase extractant have been investigated. Reversibility of sorption-desorption processes on the surface of the extractant has been shown.

Head of the laboratory of chemistry for organo-mineral materials Department of analytical chemistry Taras Shevchenko National University of Kyiv 60 Vladimirskaya Str., Kiev Ukraine 01601
tel: +380-97-0980693, e-mail: vnzaitsev@gmail.com, http://anchem.knu.ua/ua/main_ukr.html
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