Al2o3 Coated With 3-n-propyl-1-azonia-4-azabicyclo[2. 2.2]octane Silsesquioxane Chloride And Its Use For Immobilization Of Cobalt(ii) Tetrasulfonated Phthalocyanine In Oxalic Acid Electrooxidation

A water-soluble polymer prepared by sol-gel process, 3-n-propyl-1-azonia-4- azabicyclo[2.2.2]octane silsesquioxane chloride, was adsorbed on alumina surface. This polymer-coated alumina was able to effectively immobilize cobalt(II) tetrasulfonated phthalocyanine complexes as counter ions. Cobalt phthalocyanine immobilized in this way is well and tightly adsorbed on Al 2O3/3-n-propyl-1-azonia-4-azabicyclo[2.2.2]octane silsesquioxane chloride surface. Furthermore, when incorporated to a carbon paste electrode showed a good electrocatalytic response toward the acid oxalic oxidation, making it a suitable electrode material. A linear relationship (r = 0.998) between the current responses obtained by chronoamperometric measurements and the oxalic acid concentration in the range of 7.4 × 10-5 - 9.1 × 10-4 mol L-1 was observed. A detection limit of 18 μmol L-1 was also determined. ©2008 Sociedade Brasileira de Química.194755761Templin, M., Franck, A., Du Chesne, A., Leist, H., Zhang, Y., Ulrich, R., Schädler, V., Wiesner, U., (1997) Science, 278, p. 1795Lee, K., Itharaju, R.R., Puleo, D.A., (2007) Acta Biomaterialia, 3, p. 515Yuan, J., Zhou, S., You, B., Wu, L., (2005) Chem. Mater, 17, p. 3587Fujiwara, M., Nishiyama, M., Yamamura, I., Ohtsuki, S., Nomura, R., (2004) Anal. Chem, 76, p. 2374Sayari, A., Hamoudi, S., (2001) Chem. Mater, 13, p. 3151Tien, P., Chau, L.K., Shieh, Y.Y., Lin, W.C., Wei, G.T., (2001) Chem. Mater, 13, p. 1124Gushikem, Y., Alfaya, R.V.S., Alfaya, A.A.S., (1998) Br PI, , 9.803.053-AArenas, L.T., Langaro, A., Gushikem, Y., (2003) J. Sol-Gel Sc. Tech, 28, p. 51Tundo, P., Venturello, P., Angeletti, E., (1982) J. Am. Chem. Soc, 104, p. 6547Wotring, V.J., Johnson, D.M., Bachas, L.G., (1990) Anal. Chem, 62, p. 1506Scindia, Y.M., Pandey, A.K., Reddy, A.V.R., (2005) J. Membr. Sci, 249, p. 143Arenas, L.T., Vaghetti, J.C.P., Moro, C.C., Lima, E.C., Benvenutti, E.V., Costa, T.M.H., (2004) Mater. Lett, 58, p. 895Kobayasbit, J., Anson, F.C., (1991) J. Phys. Chem, 95, p. 2595Ribeiro, E.S., Gushikem, Y., (1999) Electroanalysis, 11, p. 1280Lucho, A.M.S., Pissetti, F.L., Gushikem, Y., (2004) J. Sol-Gel Sc. Tech, 275, p. 251Arenas, L.T., Aguirre, T.A.S., Langaro, A., Gushikem, Y., Benvenutti, E.V., Costa, T.M.H., (2003) Polymer, 44, p. 5521Castellani, A.M., Gonçalves, J.E., Gushikem, Y., (2002) J. New Mat. Electrochem. Syst, 5, p. 169Arenas, L.T., Dias, S.L.P., Moro, C.C., Costa, T.M.H., Benvenutti, E.V., Lucho, A.M.S., Gushikem, Y., (2006) J. Colloid Interface Sci, 297, p. 244Min Jin, Z., Jiang Pan, Y., Feng Li, X., Lin Hu, M., Shen, L., (2003) J. Mol. Struct, 660, p. 67Marzocchi, M.P., Sbrana, G., Zerbi, G., (1965) J. Am. Chem. Soc, 87, p. 1429Fidalgo, A., Ilharco, L.M., (2004) Chem. Eur. J, 10, p. 392Ray, S., Vasudevan, S., (2003) Inorg. Chem, 42, p. 1711Tackley, D.R., Dent, G., Smith, W.E., (2001) Phys. Chem. Chem. Phys, 3, p. 1419Anson, F.C., (1966) Anal. Chem, 38, p. 54Xuan, G.S., Jang, S., Kwag, G., Kim, S., (2005) Bull. Korean Chem. Soc, 26, p. 671Lucho, A.M.S., Oliveira, E.C., Pastore, H.O., Gushikem, Y., (2004) J. Electroanal. Chem, 73, p. 55Bard, A.J., Faulkner, L.R., (2001) Electrochemical Methods. Fundamentals and Applications, , 2nd ed, Wiley: New York, ch. 9Yamazaki, S., Yamada, Y., Fujiwara, N., Ioroi, T., Siroma, Z., Senoh, H., Yasuda, K., (2007) J. Electroanal. Chem, 602, p. 96Casella, I.G., (1999) Electrochim. Acta, 44, p. 3353Mandanas, M.M., Shaffer, W., Adair, J.H., (2002) J. Am. Ceram. Soc, 85, p. 2156Shaidarova, L.G., Chelnokova, I.A., Gedmina, A.V., Budnikov, G.K., Ziganshina, S.A., Mozhanova, A.A., Bukharaev, A.A., (2006) J. Anal. Chem, 61, p. 37

Synthesis and characterization Of SiO2-Nb2O5 systems prepared by the sol-gel method: structural stability studies

X-Ray diffraction (XRD), N-2 absorption (BET specific surface area), transmission electron microscopy (TEM), Raman and Fourier infrared (FT-IR) spectroscopic techniques have been applied to characterize the texture, structure and niobia-silica interaction of SiO2-Nb2O5 systems prepared by the sol-gel method containing different amounts of Nb2O5 and calcined at temperatures between 393 and 1473 K. For a small loading of niobia, amorphous niobium species were well dispersed in the silica LIP to 1273 K. Crystallization is observed only after thermal treatment at 1473 K, with the T-phase predominating as observed by XRD and TEM analyses and confirmed by Raman spectra. For samples with a higher amount of niobia. the formation of a T-Nb2O5 phase was observed at 1273 K, and the H-Nb2O5 phase predominates at 1473 K. FT-IR results indicate the presence of Si-O-Nb linkages at the silica-niobia interface, formed during preparation, which are responsible for the higher structural stability of the SiO2-Nb2O5 system. The stability of the SiO2-Nb2O5 system is confirmed by obtaining high specific surface areas even after the high temperature of calcination.1282552255

Adsorption of hidrogen peroxide on the surface of silica - titania mixed oxide obtained by the sol-gel processing method

This work describes the sol-gel mixed oxide SiO2/TiO2 property, ST, as prepared, and submitted to heat treatment a 773 K, STC. SEM and EDS images show, within magnification used, a uniform distribution of the TiO2 particles in SiO2/TiO2 matrix. Both, ST and STC adsorb hydrogen peroxide on the surface and through EPR and UV-Vis diffuse reflectance spectra, it was possible to conclude that the species on the surface is the peroxide molecule attached to the Lewis acid site of titanium particle surface, alphaTi(H2O2)+. As the material is very porous, presumably the hydrogen peroxide molecule is confined in the matrix pores on the surface, a reason why the adsorbed species presents an exceptional long lived stability.4145Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

X-ray Photoelectron Spectroscopy And Mossbauer Spectroscopy Study Of Iron(iii) And Antimony(v) Oxides Grafted Onto A Silica Gel Surface

[No abstract available]191325132

Use of ruthenium-(ethylenedinitrito)-tetraacetic acid monohydrate ion immobilized on zirconium(IV) oxide coated silica gel surface as an amperometric sensor for oxygen in water

[Ru(edta)H2O](-) adsorbed on zirconium(IV) oxide coated on the surface of silica gel was used for the construction of an amperometric sensor for O-2 in water, using a carbon paste electrode. The adsorbed complex electrocatalyses the oxygen reduction reaction at -250 mV versus SCE. The cathodic current was linear for an oxygen concentration between 0.55 and 8.0 ppm, with a correlation coefficient of 0.998 and a relative standard deviation of 2.7%. The sensor response is constant within the solution pH values 2.0 and 6.5. The concentration of O-2 in a natural sample was also determined.321250350

Selective Spectrophotometric Determination Of Trace Amounts Of Chromium(vi) Using A Flow Injection System With A Microcolumn Of Zirconium(iv) Oxide Modified Silica Gel

Zirconium(IV) oxide coated on a silica gel surface was found to be very effective for extracting CrVI from aqueous solutions at a pH of about 3. A microcolumn packed with this material was inserted into a flow injection system for the separation and preconcentration of CrVI. By this process, a concentration level of 2 ppb was detected with a relative standard deviation of 2.4%. Because of the high selectivity of the immobilized substrate, it was possible to determine CrVI in the presence of larger amounts of other ions. The analysis was also carried out on natural water spiked with CrVI, and compared with a standard method.11761029103

Cellulose aluminium oxide coated with organofunctional groups containing nitrogen donor atoms

A composite of cellulose and aluminium oxide, cel/Al2O3, was prepared and further modified with organofunctional groups by reacting with the coupling reagent (C2H5O)(3)SiL, where L represents -(CH2)(3)NH2, -(CH2)(3)NH(CH2)(2)NH2, -(CH2)(3)NH(CH2)(2)NH(CH2)(2)NH2 or -(CH2)(3)N(C3H3)N [-N(C3H3)N = imidazolyl radical], abbreviated to ap, enp, dienp and imp, respectively. The experimental preparation procedures were very reproducible and resulted in the following values for the amount of organofunctional groups grafted on cel/Al2O3 (average values in mmol g(-1)): cel/Al2O3/Si(ap) = 0.35; cel/Al2O3/Si(enp) = 0.30; cel/Al2O3/Si(dienp) = 0.25 and cel/Al2O3/Si(imp) = 1.0. The Al-27 MAS NMR spectra, which show an intensification of the area under the peak at 62 ppm due to Al in a tetrahedral environment, and the increase of the Al/C atomic ratios (determined from X-ray photoelectron spectra) after reaction with the coupling reagents indicate that Al atoms have migrated to the surface. This indicates that (C2H5O)(3)SiL is adsorbed on the matrix surface and reacts with the AlOH groups forming Al-O-Si bonds. The adsorption isotherms from ethanol solutions of FeCl3, CuCl2 and ZnCl2 were obtained at 298 K. The average stability constants were determined for each metal halide and the results indicated that the constants for the bi- and tridentate ligands, enp and dienp, are slightly higher than those for ap and imp, both monodentate ligands.10112526253

ANTIMONY(V) OXIDE GRAFTED ONTO A SILICA-GEL SURFACE - ACIDIC PROPERTIES AND THERMAL-STABILITY

Antimony(v) oxide grafted onto a silica gel surface was obtained in highly dispersed form, with antimony density of 0.65 atoms nm-2. The material presents Bronsted and Lewis acid properties different from pyrochlore, Sb2O5. These sites disappear upon thermal treatment at 500-degrees-C owing to reaction ot antimony oxide with the silica surface.88213193319

Antimony(v) Oxide Grafted Onto A Silica Gel Surface: Acidic Properties And Thermal Stability

Antimony(v) oxide grafted onto a silica gel surface was obtained in highly dispersed form, with antimony density of 0.65 atoms nm-2. The material presents Brønsted and Lewis acid properties different from pyrochlore, Sb2O5. These sites disappear upon thermal treatment at 500°C owing to reaction of antimony oxide with the silica surface.88213193319

Electronic spectra of some Ni2+ octahedral complexes: A practical introduction to the crystal field theory in the undergraduate course.

ELECTRONIC SPECTRA OF SOME Ni2+ OCTAHEDRAL COMPLEXES: A PRACTICAL INTRODUCTION TO THE CRYSTAL FIELD THEORY IN THE UNDERGRADUATE COURSE. The experiment introduces the undergraduate students to the crystal field theory. The electronic spectra of the octahedral complexes of [Ni(L)(n)](2+) (L = H2O dmso, NH3 and en) obtained in the experiment are used to calculate 10Dq and B parameters. The experiment shows how the parameters can be calculated and correlated with the nature of the ligands and the field intensities produced.28115315