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

Abstract

Um polímero solúvel em água, preparado pelo método sol-gel e designado cloreto de 3-n-propil-1-azonia-4-azabiciclo[2.2.2]octano silsesquioxano, foi adsorvido sobre a superfície da alumina. Essa alumina recoberta com o polímero foi capaz de imobilizar efetivamente complexos de ftalocianina tetrassulfonada metalada com Co(II) como contra-íons. A ftalocianina de cobalto imobilizada dessa forma fica fortemente aderida sobre a superfície do cloreto de Al 2 O 3 /3-n-propil-1-azonia-4-azabiciclo[2.2.2]octano silsesquioxano. Além disso, quando incorporada a um eletrodo de pasta de carbono mostra uma boa resposta eletrocatalítica para a oxidação de ácido oxálico. Foi obtida uma relação linear (r = 0,998) para o gráfico de correntes de resposta obtidas por cronoamperometria e a concentração de ácido oxálico na faixa de 7.4 × 10 -5 a 9.1 × 10 -4 mol L 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 2 O 3 /3-npropyl-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.

Capillary pressure driven water movement in wet unsaturated porous media: effect of particle electric charge

“…Particularly, surface area value of sample A agrees with the value indicated elsewhere. 28 Notwithstanding, a low correlation of particle size supplied by the manufacturer with specific surface area obtained in this work is observed, and it is caused by particle agglomeration, as discussed below. Figure 2 The micrograph of Sample A, Figure 2A, shows agglomeration of these a-alumina particles.…”

Surface modification of alumina nanoparticles with silane coupling agents

“…The infrared spectra (Figure 2) of alumina nanoparticles AL-2 and AL-S2 have peaks in the 2960 and 2860 cm -1 range, which can be assigned to the stretching of the C-H bonds 4 of the silane coupling agent (SCA) used for the preparation of AL-S1 and AL-S2. Furthermore, the broad absorption in the 1200-950 cm -1 range, 17 indicates the formation of Al-O-Si and Si-O-Si bonds.…”

“…Alumina and other oxides are widely found in many applications including support for catalysts, 1 organometallic 2 (including metal carbonyl clusters), 3 metal-organic 4 and luminescent compounds, 5 formulations for dental applications, 6 additives for polymer (nano)composites, 7 ceramic membranes, 8 pre-concentration reactors 9 and stationary phases for chromatography 10 to name a few. When dealing with multi-component systems, the interface plays a decisive role on dispersion and adhesion between the continuous phase (matrix) and the additives (fillers).…”

“…amines), but silane coupling agents and other siloxane precursors have been most extensively used to modify the surface of alumina for different purposes. 4,7,8,11,14 Silylated alumina can improve the thermo-oxidative stability of thermoplastic elastomers [poly(ether-block-amide), [poly(ether-bamide), PEBAX ® polymers], 14 and can be used for the immobilization of electrochemically active species such as metalloporphyrins. 4 Coupling of organic groups onto the surface of oxides (MO x : where M can be any transition metal, aluminum Prado et al 2239 Vol.…”

Materiais híbridos à base de sílica obtidos pelo método sol-gel

“…64,78 Mais recentemente, foi demonstrado que silsesquioxanos e híbridos à base de sílica contendo grupos orgânicos carregados positivamente também podem apresentar essa propriedade de autoorganização. [80][81][82][83][84] Esses materiais apresentam apreciável solubilidade em solventes com elevada constante dielétrica, como água e etanol, consequentemente, podem ser facilmente depositados sobre outras matrizes inorgânicas, [85][86][87][88] ou mesmo utilizados como precursores moleculares para síntese de híbridos contendo teor inorgânico mais elevado. 29,89,90 Adicionalmente, pelo fato desses silsesquioxanos ou híbridos carregados possuírem um contra-íon em sua estrutura, tornam-se potencialmente importantes em diversas áreas, tais como trocadores iônicos, [91][92][93][94][95] na separação e adsorção química e no desenvolvimento de sensores eletroquímicos.…”