Anchored fibrous chrysotile silica and its ability in using nitrogen basic centers on cation complexing from aqueous solution

Fonseca, Maria G.; Filho, Edson Cavalcanti da Silva; Machado, Ricardo S. de A.; Arakaki, Luiza N.H.; Espı́nola, José G.P.; Oliveira, Severino F. de; Airoldi, Cláudio

doi:10.1016/s0927-7757(03)00421-7

Cited by 15 publications

(8 citation statements)

References 35 publications

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“…In recent years, many endeavors have been dedicated to assemble AgNPs on the spherical silicon oxide structures; the methods include pretreatment-chemical plating, self-assembly chemical plating, and ultrasonication . Although various architectures with Ag/silica nanocomposites have been observed in solution-based processes, synthesis of one-dimensional Ag/silica nanocomposites, especially Ag/natural silica nanostructures, is rarely reported. − In particular, as an excellent natural catalyst support candidate, chrysotile (Mg 6 [Si 4 O 10 ](OH) 6 ) has attracted much attention because of its outstanding physicochemical properties, such as fantastic specific surface area, tunable pore structures, thermal stability, and special surface network topological structure. − Moreover, there is a great amount of hydroxyl on the exterior surface of chrysotile, which causes easy grafting and decoration on the chrysotile surface by functional organic molecules …”

Section: Introductionmentioning

confidence: 99%

“…22−24 Moreover, there is a great amount of hydroxyl on the exterior surface of chrysotile, which causes easy grafting and decoration on the chrysotile surface by functional organic molecules. 25 Herein, we report a novel preparation process of synthesizing uniform silver nanoparticles/silica nanowires (AgNPs/ SiO 2 NWs) nanocomposites with well-defined nanostructures in an aqueous solution. The silica nanowires were functionalized by electron-rich 3-aminopropyltriethoxysilane, and AgNPs were restored by sodium borohydride in the presence of electron-deficient trisodium citrate.…”

Section: ■ Introductionmentioning

confidence: 99%

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Natural Chrysotile-Based Nanowires Decorated with Monodispersed Ag Nanoparticles as a Highly Active and Reusable Hydrogenation Catalyst

et al. 2015

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Silver nanoparticles/silica nanowires (AgNPs/SiO 2 NWs) with the nearly uniform diameters of 35 ± 5 nm were successfully fabricated by two steps consisting of the preparation of the silica nanowires (SNWs) by chemical dispersing and acid leaching from the natural mineral chrysotile and an in situ reduction approach (for AgNPs). The highly dispersed AgNPs assembled on the surface of SiO 2 NWs through the in situ reduction of Ag + by NaBH 4 were confirmed by transmission electron microscopy (TEM) and UV−vis absorption spectra. The catalytic activities of the as-prepared Ag/SiO 2 NWs (silver nanoparticles/silica nanowires) nanocomposites with different concentrations were assessed via using a classical reaction based on the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH 4 as the reductant. The results demonstrated that all the nanocomposite catalysts exhibited high catalytic activities because the nearly monodispersed AgNPs were embedded on the surface of SiO 2 NWs, allowing effective active contact with the reactants and catalysis of the reaction. In particular, the asprepared Ag/SiO 2 NWs nanocomposites with 5 mL of AgNPs exhibited excellent catalytic activitiy. These AgNPs/SiO 2 NWs nanocomposites could be easily reused without a decline of the catalytic activities due to chrysotile natural mineral frameworks with large amounts of active sites.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Natural Chrysotile-Based Nanowires Decorated with Monodispersed Ag Nanoparticles as a Highly Active and Reusable Hydrogenation Catalyst

et al. 2015

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“…Some of our papers [1][2][3][4] have developed an improved calorimetric titration method to obtain energies evolved at different surface coverages and the corresponding amount of substance bound. Much isothermal calorimetry has been done on adsorption of heavy metals [5][6][7][8], an area stimulated by problems of practical importance such as adsorption by soil of highly toxic solutions. Silica gel (Fluka) with particle size 0.063-0.200 mm (70-230 mesh), having a mean pore diameter of 60 Å, was used as support.…”

Section: Introductionmentioning

confidence: 99%

Measurement of cation binding to immobilized vanillin by isothermal calorimetry

Vieira

Cestari

Santos

et al. 2006

Journal of Colloid and Interface Science

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“…A crisotila, amianto ou asbesto é um filossilicato natural fibroso do grupo das serpentinas em estrutura do tipo 1:1, de fórmula empírica Mg 3 Si 2 O 5 (OH) 4 , com uma camada de sílica tetraédrica (tridimita) recoberta por camada de hidróxido de magnésio (brucita), com distância interlamelar 52 de 730 pm. Como mencionado, a disposição de grupos OH na superfície facilita a imobilização de agentes sililantes no processo de imobilização de moléculas com centros básicos nitrogenados, com finalidade para remover cátions 53,54 . Por outro lado, quando a sílica é extraída da crisotila, um teor maior de agente sililante é imobilizado, o que possibilita o emprego na remoção de maneira mais efetiva 55 .…”

Section: Compostos Lamelaresunclassified

A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

Airoldi¹

2008

Quím. Nova

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cation removal by using nitrogenated basic centers. The data demonstrate the importance of the desired groups when free or immobilized on natural or synthesized inorganic polymers through silanol groups. Thus, the most studied silica gel is followed by natural crysotile and talc polymers, and the synthesized mesopore silicas, talc-like, silicic acids, phosphates and phyllosilicates. The organic natural biopolymeric chitin and cellulose were chemically modified to improve the availability of the amine groups or the reactivity with desirable molecules to enlarge the content of basic centers. The cation removal takes place at the solid/liquid interface and some interactive effects have their thermodynamic data determined.Keywords: inorganic polymer; biopolymer; cation removal. INTRODUÇÃONos dias de hoje, quando se veicula assuntos relacionados com superfícies, principalmente na área de Química Inorgânica, os interessados se voltam mais diretamente à rotulação dos profissionais atuantes como químicos de materiais. Porém, muitas vezes são esquecidos os aspectos envolvendo as ligações efetuadas entre os átomos, que estão em quantidade maiores ou menores na formação do esqueleto polimérico. Mesmo sem o conhecimento de tais detalhes e ainda sobre a estrutura é possível empregar o material em atividades tanto acadêmicas como tecnológicas, sendo comumente destacada a propriedade da adsorção. Curiosamente, o material derivado da queima ou extraído de minas naturais, após tratamento, deriva o chamado carvão ativado, o qual foi o primeiro material usado para a remoção de metais pesados contidos em efluentes industriais. No entanto, em qualquer processo operacional, o custo envolvido precisa ser examinado para que seja viável o uso, pois o preço cresce em função das especificidades requeridas e, de fato, a purificação é bastante relevante, o que chega a inviabilizá-lo na adsorção, mas que possibilita o emprego mais amplo somente em pequenas escalas laboratoriais 1 . Diante dos aspectos econômicos limitantes na obtenção do carvão de alta pureza, as pesquisas foram paulatinamente direcionadas para outras fontes alternativas. Um ponto marcante neste estudo foi buscar materiais naturais de baixo custo, que pudessem ter alta capacidade de adsorção, o que implicava na existência de centros quimicamente ativos na superfície, para que pudessem atuar com alta eficiência na retenção de cátions indesejáveis existentes em um leito aquoso contaminado. Nesta direção, o progresso do campo passou a ser mais eficaz após o conhecimento das funções quí-micas disponíveis nas superfícies dos materiais e possíveis tipos de ligações que poderiam formar frente a um determinado soluto, no decorrer do processo de adsorção na interface sólido/líquido 2 . Uma maneira de se obter o material com baixo custo é explorar fontes amplamente encontradas na natureza, que exijam operações simples para chegar a um composto final de composição definida e de alta pureza, fato que nem sempre é alcançado. Dentre uma série de materiais, os zeólitos se ajustam com essas...

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Anchored fibrous chrysotile silica and its ability in using nitrogen basic centers on cation complexing from aqueous solution

Cited by 15 publications

References 35 publications

Natural Chrysotile-Based Nanowires Decorated with Monodispersed Ag Nanoparticles as a Highly Active and Reusable Hydrogenation Catalyst

Natural Chrysotile-Based Nanowires Decorated with Monodispersed Ag Nanoparticles as a Highly Active and Reusable Hydrogenation Catalyst

Measurement of cation binding to immobilized vanillin by isothermal calorimetry

A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

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