Particle formation in the hydrolysis of tetraethyl orthosilicate in pH buffer solution

Nagao, Daisuke; Osuzu, Hideyuki; Yamada, Akira; Mine, Eiichi; Kobayashi, Yoshio; Konno, Mikio

doi:10.1016/j.jcis.2004.06.041

Cited by 51 publications

(33 citation statements)

References 17 publications

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“…At low EtOH content, TEOS is not fully solubilised at the beginning of the reaction and it takes a certain time for both the solubility and the equilibrium to be achieved. The subsequent pH increase during the later stage of the reaction at high EtOH content is consistent with initial formation of acidic silanol groups (Si-OH) during TEOS hydrolysis followed by their disappearance by condensation reactions (Si-O-Si), proposed by Nagao et al [18]. EtOH effectively enhances the propensity of the silica species to condense, via formation of relatively reactive Si-OH species.…”

Section: Influence Of the Etoh Concentration On The Basic Hydrolysis supporting

confidence: 85%

Co-precipitation of silica and alkaline-earth carbonates using TEOS as silica source

Voinescu

Kellermeier

Carnerup

et al. 2007

Journal of Crystal Growth

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We explore the use of tetraethoxysilane (TEOS) as a silica source for the formation of carbonate-silica composite materials known as 'biomorphs'. The basic hydrolysis of TEOS furnishes silica in a controllable fashion, allowing a significantly higher reproducibility of the obtained silica-barium and silica-strontium carbonate co-precipitates compared to commercial water glass silica used so far. We further discuss the influence of ethanol used as a co-solvent on the morphologies of biomorphs, which are examined by optical microscopy, field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX).

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Section: Influence Of the Etoh Concentration On The Basic Hydrolysis supporting

confidence: 85%

Co-precipitation of silica and alkaline-earth carbonates using TEOS as silica source

Voinescu

Kellermeier

Carnerup

et al. 2007

Journal of Crystal Growth

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“…where C h is the hydrolysis constant that is equal to 0.21 m 3 /(mol s) obtained from experimental data [21]. [OH − ] is calculated by:…”

Section: Effect Of Reaction Time On Morphology and Size Of Silica-coamentioning

confidence: 99%

“…where K b is the association constant of a weak base of ammonium hydroxide (pK b = 7.3 in ethanol-water system) [21]. By assuming that the concentration of ammonium hydroxide, [NH 4 OH], is constant, the integration of Eq.…”

Section: Effect Of Reaction Time On Morphology and Size Of Silica-coamentioning

confidence: 99%

Characterization of silica-coated silver nanoparticles prepared by a reverse micelle and hydrolysis–condensation process

Hagura

Widiyastuti

Iskandar

et al. 2010

Chemical Engineering Journal

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“…[12] In the literature, the influences of the type and the alkyl chain length of amines, the concentrations of amines and TEOS on the formation and the porosity of the formed silica microspheres have been discussed. For example, Nagao et al [13] prepared SiO 2 microspheres with the addition of NH 3 , methylamine and dimethylamine. It was concluded that the concentration of NH 3 needed for the formation of silica microspheres was much higher than that of amines.…”

Section: Introductionmentioning

confidence: 99%

An in-depth investigation on the formation of nanoporous silica microspheres in diluted dodecylamine solutions

Liu

Zhao

2015

Journal of Experimental Nanoscience

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The morphology and textural characteristics of silica products formed via the hydrolysis and condensation of tetraethyl orthosilicate in increasing diluted dodecylamine solutions have been investigated. The results show that the pH values of the synthesis media increase with the initial additions of water. The formation of silica speeds up as the solution is diluted. As a result, microporous silica microspheres with increasing surface areas, pore volumes, pore and particle sizes are formed by a monomer addition mechanism. Further increases in the amount of water result in the decrease of the concentrations of OH ¡ . Consequently, the formed silica seeds become less active and the diffusion of silica species is accelerated. The monomer addition process thus becomes difficult. The self-nucleation of silica species leads to the formation of large quantities of primary silica nano particles. In order to minimise the internal energy of the reaction system, the nanoparticles aggregate to form micrometre-sized silica microspheres with a relatively loose structure. The synthesised microspheres can be used in the removal of organic pollutants in water. It is shown that the nanoporous silica microspheres formed by the aggregation mechanism have a faster dye adsorption rate and a higher adsorption capacity than those formed by the monomer addition mechanism.

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Particle formation in the hydrolysis of tetraethyl orthosilicate in pH buffer solution

Cited by 51 publications

References 17 publications

Co-precipitation of silica and alkaline-earth carbonates using TEOS as silica source

Co-precipitation of silica and alkaline-earth carbonates using TEOS as silica source

Characterization of silica-coated silver nanoparticles prepared by a reverse micelle and hydrolysis–condensation process

An in-depth investigation on the formation of nanoporous silica microspheres in diluted dodecylamine solutions

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