The Gelation of Sodium Silicate. Effect of Sulfuric Acid, Hydrochloric Acid, Ammonium Sulfate, and Sodium Aluminate.

Merrill, Reynold C.; Spencer, Ross L.

doi:10.1021/j150480a009

Cited by 50 publications

(22 citation statements)

References 5 publications

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“…In accordance with a previously reported protocol, the gel time was determined as the moment when the gel broke away from the wall of the Petri dish, instead of flowing as a liquid, when the dish was tilted. 28,29 The results plotted in Figure 3 indicate that the silica gel formation was slow when the pH was low (pH 2−4), due to the low concentration of hydroxyl ions. Gelation was most rapid between pH 4 and 6 because the sol passed through the isoelectric point, at which it did not carry a net electrical charge.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Hydrogen Peroxide Stability in Silica Hydrogels

Sudur

Pleskowicz

Orbey

2015

Ind. Eng. Chem. Res.

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Hydrogen peroxide (H 2 O 2 ) entrapment in silica hydrogels has potential to be used in various industrially important applications to increase H 2 O 2 stability. In this study, optimum conditions for hydrogel formation and H 2 O 2 stability were determined by varying the sodium content and initial H 2 O 2 concentration. Higher retention and better stability of H 2 O 2 were achieved with hydrogels at room temperature at low sodium concentration. Retention values of 89% were obtained with initial H 2 O 2 concentrations up to 10 wt %. H 2 O 2 decomposition in hydrogels followed a first-order reaction. Hydrogels were characterized by measuring their surface area, pore size, and pore size distribution by Brunauer−Emmett−Teller analysis and scanning electron microscopy. Mesoporous (3−24 nm) hydrogels with high surface area (1000−1400 m 2 /g) were obtained. In addition, the melting point of the entrapped H 2 O 2 -water mixture in the hydrogels was studied by low temperature differential scanning calorimetry.

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Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Hydrogen Peroxide Stability in Silica Hydrogels

Sudur

Pleskowicz

Orbey

2015

Ind. Eng. Chem. Res.

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“…25,26 It was found that the clear sodium silicate solution (Fig. 2a) would be converted into milky gels (Fig.…”

Section: Characterizationmentioning

confidence: 99%

Flexible aerogels with interpenetrating network structure of bacterial cellulose–silica composite from sodium silicate precursor via freeze drying process

Sai

Xiang

et al. 2014

RSC Adv.

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Bacterial cellulose (BC)-silica composite aerogels (CAs) with interpenetrating network (IPN) microstructure are prepared through a permeation sol-gel process followed by freeze drying. The IPN structure is constructed by diffusing the precursor into a three-dimensional (3D) BC matrix followed by permeating the catalyst into the BC network gradually to promote the in situ condensation of precursor to form a SiO 2 gel skeleton from outside to inside. The precursor used here is Na 2 SiO 3 instead of traditional tetraethoxysilane. This IPN structure could offer excellent mechanical properties to aerogels, and is essential to prepare flexible aerogels by freeze drying. The compression modulus of CAs could be adjusted in the range of 0.38 MPa to 16.17 MPa. The BC-silica CAs exhibit low density (as low as 0.011 g cm À3 ), high specific surface area (as high as 534.5 m 2 g À1 ) and low thermal conductivity (less than 0.0369 W m À1 K À1 ). Furthermore, the contact angle of the hydrophobization modified CAs is as high as 145 . The outstanding hydrophobicity and the large specific surface area endow the hydrophobic CAs with excellent oil absorption capability on the water surface. Moreover, the hydrophobic CAs that had absorbed oil could be washed and recycled.

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“…The point of gelation was taken as the earliest moment at which the gel broke away from the wall instead of flowing as a liquid when the beaker was tilted [4,15]. The random error on the determination of gelation time is about 5%.…”

Section: Preparation Process Of Productsmentioning

confidence: 99%