Synthesis of a Thermally Stable Silica/p-Anisidine Sol–Gel Powdered Material

Pavan, Flávio André; Franken, Leonardo; Moreira, Cristiano A.; Costa, Tânia Maria Haas; Benvenutti, Edílson V.; Gushikem, Yoshitaka

doi:10.1006/jcis.2001.7705

Cited by 25 publications

(12 citation statements)

References 17 publications

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“…The T d values of 20‐CS and 30‐CS were slightly higher than that of chitosan, whereas 10‐CS had a lower T d . The improvement of the thermal stability could be explained by a reinforcing effect on the structure of the composite aerogel when the chitosan content reached 20 wt %, and the lower T d of 10‐CS might have been because large amounts of silica particles disrupted the original intermolecular forces between the chitosan molecules . Among all of the samples, 20‐CS exhibited an optimal thermal stability with a T d of nearly 300°C.…”

Section: Resultsmentioning

confidence: 99%

Hydrophobic and nanoporous chitosan–silica composite aerogels for oil absorption

Liu

Dong

et al. 2014

J of Applied Polymer Sci

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Hydrophobic and nanoporous chitosan-silica composite aerogels with low density, high porosity, and superior oil absorbency were successfully prepared by a typical sol-gel method and a two-step hydrophobic treatment. The morphologies, porosity characteristics, mechanical properties, thermal stability, hydrophobicity, and oil absorbencies of the composite aerogels were systematically investigated. The nitrogen physisorption analysis showed that composite aerogels had large specific surface areas and uniform nanoporous structures. In addition, the composite aerogels could support 7000 times its own weight; this indicated the role of the supporting skeleton played by chitosan. The hydrophobicity and lipophilicity was demonstrated with a water contact angle of 137 and an oil contact angle of 0 . Importantly, the composite aerogel with 20 wt % chitosan had a relatively high oil absorbency of 30 g/g and could be reused up to 10 times. Therefore, the chitosan-silica composite aerogels in this study had a broad prospect to be used as efficient and recyclable oil absorbents.

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Section: Resultsmentioning

confidence: 99%

Hydrophobic and nanoporous chitosan–silica composite aerogels for oil absorption

Liu

Dong

et al. 2014

J of Applied Polymer Sci

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“…where N f is the organic coverage (mol/g) obtained from elemental analysis presented in Table 1, N is Avogadro's number, and S BET is the specific surface area [33]. The obtained d value is 3.1 organic groups per nm 2 .…”

Section: Preparation and Characterization Of Pd II -Mpsg Materialsmentioning

confidence: 98%

Palladium(II) chemically bonded to silica surface applied to the separation and identification of polycyclic aromatic sulfur heterocycles in heavy oil

et al. 2013

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Separation of polycyclic aromatic sulfur heterocycles among themselves and also from interferents in petrochemical matrices is a challenging task because of their low concentration, matrix complexity, and also due to the presence of polyaromatic hydrocarbons, as they present similar physico-chemical properties. Therefore, the objective of this work was preparation, characterization, and application of a stationary phase for separation of these compounds in a heavy gas oil sample and their identification by comprehensive two-dimensional gas chromatography. The stationary phase was prepared by grafting mercaptopropyltrimethoxisilane onto a silica surface, followed by palladium(II) chloride immobilization. Elemental analysis, thermogravimetry, nitrogen adsorption-desorption isotherms, infrared analysis, and scanning electron microscopy were performed to characterize this solid phase. Sulfur compounds were separated in an open column packed with the stationary phase and analyzed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometric detection. The number of compounds tentatively identified was 314 and their classes were thiophenes, benzotiophenes, dibenzothiophenes, naphthothiophenes, benzonaphthothiophenes, and dinaphthothiophenes. Separation among sulfur compounds and polyaromatic hydrocarbons was successful, which is a difficult goal to achieve with the traditionally employed solid phases. Some recalcitrant compounds (dibenzothiophenes with substituents of two and four carbons) were fully separated and tentatively identified.

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“…O aumento dessa razão produz uma elevação no teor de orgânico no material final até alcançar uma saturação, influenciando suas características morfológicas e texturais. Híbridos com menor teor orgânico apresentam maior porosidade, maior área superficial específica [52][53][54][55][56] e maior estabilidade térmica do componente orgânico. 57 O efeito da razão molar água/ortossilicato de tetraetila também foi estudado, no caso do híbrido contendo o grupo aminonaftaleno.…”

Section: (3)unclassified

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

Benvenutti¹,

Moro²,

Costa³

et al. 2009

Quím. Nova

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Recebido em 16/12/08; aceito em 16/3/09; publicado na web em 17/9/09 SILICA BASED HYBRID MATERIALS OBTAINED BY THE SOL-GEL METHOD. This review deals with silica based hybrid materials obtained by the sol-gel method. It involves concepts, classifications and important definitions regarding the sol-gel method that allows obtaining materials with organic and inorganic components dispersed in a molecular or nanometric level. We discuss the properties and characteristics of hybrid materials related to experimental synthesis conditions. We devote a special attention to the nanostructured materials, where the self-organization is imposed by the organic component. Finally, we present some important applications of these materials based on their specific properties.Keywords: organic-inorganic materials; silsesquioxanes; silica based hybrid xerogels. INTRODUÇÃOO desenvolvimento da ciência dos materiais trouxe importantes contribuições no avanço da tecnologia. A busca constante por novos materiais com desempenho e propriedades otimizadas para aplicações inovadoras e o aperfeiçoamento de materiais já existentes é um desafio e um dos motivos da evolução técnica e científica atual.1-8 Nesse contexto, encontra-se a possibilidade de combinar no nível molecular ou nanométrico os componentes orgânico e inorgânico, resultando em novos materiais conhecidos como híbridos organo-inorgânicos.9 Esses materiais híbridos, além de oferecerem a oportunidade de combinar de forma sinérgica as propriedades físico-químicas inerentes de seus constituintes, permitem obter novas propriedades, resultantes da combinação de seus componentes, devido ao tamanho reduzido dos domínios que os compõem.10-13 Para alcançar esse nível tão reduzido de dispersão, pode-se utilizar o método sol-gel de síntese, que envolve a formação de uma rede polimérica inorgânica por reações de gelificação a baixas temperaturas. As reações resultam na transição de um líquido para um sólido, sendo que os reagentes precursores dos componentes, orgânico e inorgânico, que são geralmente alcóxidos de silício ou de metais como alumínio, titânio, zircônio, se encontram inicialmente dissolvidos nesse líquido. No decorrer do processo, as reações de gelificação levam à formação de um estado sol, que se caracteriza por apresentar oligômeros que formarão cadeias de dimensões coloidais e partículas primárias dispersas. A evolução desse processo forma o estado gel que apresenta conectividade entre as unidades de dimensões coloidais, formando uma rede tridimensional, entrelaçada macroscopicamente observável.14 Além da possibilidade de obter os componentes orgânico e inorgâ-nico altamente dispersos, o método sol-gel de síntese apresenta outras características interessantes, tais como: i) as reações de gelificação são processadas a baixas temperaturas, o que permite inserir à matriz sólida biomoléculas como enzimas, proteínas e anticorpos, de difícil incorporação por outros métodos que utilizem temperaturas mais elevadas;15-17 ii) possibilidade de obter materiais sob diferentes configurações ...

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Synthesis of a Thermally Stable Silica/p-Anisidine Sol–Gel Powdered Material

Cited by 25 publications

References 17 publications

Hydrophobic and nanoporous chitosan–silica composite aerogels for oil absorption

Hydrophobic and nanoporous chitosan–silica composite aerogels for oil absorption

Palladium(II) chemically bonded to silica surface applied to the separation and identification of polycyclic aromatic sulfur heterocycles in heavy oil

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

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