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Lygin, V. I.

doi:10.1023/a:1013997717868

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…As described earlier, the higher intensity of the 3400 cm À1 band is the result of the incorporation of more disordered hydrogen bonded water molecules. Both spectra show an increase in the 3650-3740 cm À1 region which we assign to water weakly bound to silanol groups and vicinal pairs of isolated silanol [27,30]. There is also a possible contribution from the free OH stretch of water (observed at 3700 cm À1 ), water dimers, and weakly hydrogen bonded water [41,42].…”

Section: Air-silica Interfacementioning

confidence: 78%

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Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied by vibrational sum frequency generation spectroscopy

Casillas-Ituarte

Allen

2009

Chemical Physics Letters

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Section: Air-silica Interfacementioning

confidence: 78%

“…2a). Additionally, a small shoulder is observed at $3735 cm À1 , and is attributed to water weakly bound to silanol groups [30], somewhat similar to a 'silica-gel' structure [31].…”

Section: Air-silica Interfacementioning

confidence: 93%

Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied by vibrational sum frequency generation spectroscopy

Casillas-Ituarte

Allen

2009

Chemical Physics Letters

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“…Thermal treatment, particularly at temperatures above 1000 1C, results in an almost total dehydroxylation of silica surfaces with the interconversion of most silanol groups into siloxane bridges (Si-O-Si). 4,6,7,10,37 During the heating process, the hydrogenbonded and vicinal silanols are the first to disappear, followed later by the geminals. 3,6 On the other hand, isolated silanols first increase in numbers, peaking at B400 1C, before totally dehydroxylating at temperatures above 1100 1C.…”

Section: Resultsmentioning

confidence: 99%

“…3,6 On the other hand, isolated silanols first increase in numbers, peaking at B400 1C, before totally dehydroxylating at temperatures above 1100 1C. 2,6,10 Once the silica substrate is immersed in water the surface rapidly rehydroxylizes, yet only partially. 6 This effect can be visualized when comparing the SF spectra in Fig.…”

Section: Resultsmentioning

confidence: 99%

The elusive silica/water interface: isolated silanols under water as revealed by vibrational sum frequency spectroscopy

Dalstein

Potapova

Tyrode

2017

Phys. Chem. Chem. Phys.

135

149

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It has been long recognized that the surface chemistry of silica, and in particular the type and relative amount of surface bound silanol groups, plays a critical role in many of the properties associated with the material, where a typical example is the discrepant adsorption behavior observed depending on the pretreatment history of the surface. However, in spite of its importance, the direct probing of specific surface silanol groups under water has been hampered by instrumental limitations. Here we make use of vibrational sum frequency spectroscopy (VSFS) to first, identify under water the OH stretch of isolated surface silanols, and second, explore its acid/base behavior and dependence on the surface pretreatment method. The properties of other types of silanol groups (i.e. hydrogen bonded/geminal) are also inferred from the data. The ability to directly probe these functional groups under water represents a crucial step to further improving our understanding of this widely used mineral oxide.

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“…Silica and diatomite have been studied using spectroscopic techniques such as IR [3,15,22,37,38], Raman [3,39,40], and NMR (including 1 H and 29 Si analyses using solid-state NMR spectroscopy techniques [17,20,38,[40][41][42][43][44]). Other works focused on surface modification [20,[45][46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Effect of pretreatment temperature on the surface modification of diatomite with trimethylchlorosilane

et al. 2016

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Diatomite samples from Costa Rica were purified using acidic treatments with hydrochloric acid, thermally treated (400-1000°C) and then silylated with trimethylchlorosilane in toluene under inert atmosphere. The purification process allows to decrease the concentration of metals presented in the crude diatomite, as is confirmed by X-ray Fluorescence (XRF) Analysis. The silylated materials were analyzed by using Hyperpolarized 129 Xe Nuclear Magnetic Resonance Spectroscopy (HP 129 Xe NMR), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), rehydration tests, and contact angle measurements. XRD measurements indicate that diatomite is mainly amorphous, but presents several crystalline phases (kaolinite, cristobalite, and quartz). Pretreatments at high temperatures cause changes in those crystalline phases, resulting in more amorphous materials. However, there is no difference in the overall structure of purified and thermally treated diatomite samples with respect to the silylation products. In addition, SEM measurements show no effect over the pore structure of the materials. On the other hand, TGA measurements and rehydration tests show lower losses of water for silylated materials prepared using higher pretreatment temperatures. Moreover, HP 129 Xe NMR, FTIR, and contact angle measurements evidence a modification due to covalent attachment of Si(CH 3 ) 3 -groups to the surface, which increases for higher pretreatment temperatures. The results provide valuable information about external factors that influence the surface modification of diatomite. This can be useful to control modifications that can be achieved in a similar way.

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Cited by 11 publications

References 5 publications

Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied by vibrational sum frequency generation spectroscopy

Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied by vibrational sum frequency generation spectroscopy

The elusive silica/water interface: isolated silanols under water as revealed by vibrational sum frequency spectroscopy

Effect of pretreatment temperature on the surface modification of diatomite with trimethylchlorosilane

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