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LUND UNIVERSITY LIBRARIES

Development of a Surface Reduction Treatment Method of Amorphous Silica with High Porosity and Characterization of the Surface Chemistry

Lundin, Emma LU (2015) KOO920 20151
Centre for Analysis and Synthesis
Abstract (Swedish)
Den första delen av arbetet gick ut på att ta fram och utvärdera en behandlingsmetod som kan användas för att på ett kontrollerbart sätt minska den specifika ytan på amorf silika med hög porositet. Den specifika ytan är en viktig egenskap för amorf silika när det kommer till dess applikationer som absorptions- och adsorptionsmaterial. Parametrarna som studerades var pordiameter, partikelstorlek, tid, temperatur och silikakoncentration. Ytminskningen var ungefär 1.0 ± 0.3 m2/g h för silika med en pordiameter på 85Å när den behandlades i 100-gradigt Milli-Q vatten upp till 24 h. Resultaten indikerade att ytminskningen var långsammare efter 24 h och 2-3 gånger långsammare när behandlingstemperaturen ändrades till 80°C. Ytminskningen skedde... (More)
Den första delen av arbetet gick ut på att ta fram och utvärdera en behandlingsmetod som kan användas för att på ett kontrollerbart sätt minska den specifika ytan på amorf silika med hög porositet. Den specifika ytan är en viktig egenskap för amorf silika när det kommer till dess applikationer som absorptions- och adsorptionsmaterial. Parametrarna som studerades var pordiameter, partikelstorlek, tid, temperatur och silikakoncentration. Ytminskningen var ungefär 1.0 ± 0.3 m2/g h för silika med en pordiameter på 85Å när den behandlades i 100-gradigt Milli-Q vatten upp till 24 h. Resultaten indikerade att ytminskningen var långsammare efter 24 h och 2-3 gånger långsammare när behandlingstemperaturen ändrades till 80°C. Ytminskningen skedde även långsammare när pordiametern ändrades till 110Å. De utförda experimenten visade att varken partikelstorlek eller silikakoncentration påverkade ytminskningen.

Behandlingsmetodens påverkan på pordiametern, porvolymen och de kromatografiska egenskaperna undersöktes också. Behandlingsmetoden hade inte en tydlig effekt på porvolymen. Eftersom pordiametern är omvänt proportionell mot den specifika ytan så ökade pordiametern när den specifika ytan minskade.

Den andra delen av arbetet gick ut på att hitta tekniker som kan användas för att studera silikans silanolgrupper. Termogravimetrisk analys (TGA) och spektroskopiska tekniker som nuclear magnetic resonance (NMR), Raman, infrared (IR) och near infrared (NIR) användes i arbetet. De olika teknikerna visade inte tydligt och systematiskt att behandlingsmetoden påverkade silanolkoncentrationen. Kromatografiska mätningar indikerade att den relativa mängden av vicinala silanoler ökade med behandlingen och NMR mätningar indikerade att geminala silanoler minskar. De kvalitativa och kvantitativa mätningarna av silanolgrupper försvårades på grund av vatten i silikaproverna. (Less)
Abstract
A treatment method that can be used to controllably reduce the specific surface of amorphous silica with high porosity has been developed. The specific surface of amorphous silica is important for its adsorption and absorption applications. The parameters that were studied were the pore diameter, the particle size, the time of treatment, the temperature and the silica concentration. The reduction of the specific surface for silica with a pore diameter of 85Å was approximately 1.0 ± 0.3 m2/g h when the silica was treated in Milli-Q water up to 24 h at a temperature of 100 °C. The results indicated that the surface reduction decreased after 24 h and the specific surface was reduced approximately 2-3 times slower when the temperature was... (More)
A treatment method that can be used to controllably reduce the specific surface of amorphous silica with high porosity has been developed. The specific surface of amorphous silica is important for its adsorption and absorption applications. The parameters that were studied were the pore diameter, the particle size, the time of treatment, the temperature and the silica concentration. The reduction of the specific surface for silica with a pore diameter of 85Å was approximately 1.0 ± 0.3 m2/g h when the silica was treated in Milli-Q water up to 24 h at a temperature of 100 °C. The results indicated that the surface reduction decreased after 24 h and the specific surface was reduced approximately 2-3 times slower when the temperature was changed from 100 °C to 80 °C. When the pore diameter was changed to 110Å the surface reduction rate also was slower. The experiments showed that neither the particle size nor the concentration of silica had an impact on the surface reduction.

The impact of the treatment methods on the pore diameter, the pore volume and the chromatographic performance were also studied. The investigated treatment methods did not have an impact on the pore volume. Since the pore diameter is inversely proportional to the surface area the pore diameter increased when the specific surface decreased.

The second part of the work consisted of finding techniques that can be used to study the silanol groups on the surface of silica. Thermogravimetric analysis (TGA) and the spectroscopic techniques nuclear magnetic resonance (NMR), Raman, infrared (IR), and near infrared (NIR) were used in this work. The different techniques did not evidently and systematically show that the treatment methods result in an increase of the silanol concentration. NMR measurements indicated that the relative amount of geminal silanols was decreased by the treatment and chromatographic measurements indicated that the relative amount of vicinal silanols was increased. The presence of water in the samples was the main problem in the qualification and quantification of silanol groups. (Less)
Please use this url to cite or link to this publication:
author
Lundin, Emma LU
supervisor
organization
course
KOO920 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
amorphous silica, high porosity, specific surface, surface reduction, silanol groups, TGA, NMR, IR, NIR, Raman spectroscopy, materials chemistry
language
English
id
8171532
date added to LUP
2024-03-04 11:22:23
date last changed
2024-03-04 11:22:23
@misc{8171532,
  abstract     = {{A treatment method that can be used to controllably reduce the specific surface of amorphous silica with high porosity has been developed. The specific surface of amorphous silica is important for its adsorption and absorption applications. The parameters that were studied were the pore diameter, the particle size, the time of treatment, the temperature and the silica concentration. The reduction of the specific surface for silica with a pore diameter of 85Å was approximately 1.0 ± 0.3 m2/g h when the silica was treated in Milli-Q water up to 24 h at a temperature of 100 °C. The results indicated that the surface reduction decreased after 24 h and the specific surface was reduced approximately 2-3 times slower when the temperature was changed from 100 °C to 80 °C. When the pore diameter was changed to 110Å the surface reduction rate also was slower. The experiments showed that neither the particle size nor the concentration of silica had an impact on the surface reduction. 

The impact of the treatment methods on the pore diameter, the pore volume and the chromatographic performance were also studied. The investigated treatment methods did not have an impact on the pore volume. Since the pore diameter is inversely proportional to the surface area the pore diameter increased when the specific surface decreased.

The second part of the work consisted of finding techniques that can be used to study the silanol groups on the surface of silica. Thermogravimetric analysis (TGA) and the spectroscopic techniques nuclear magnetic resonance (NMR), Raman, infrared (IR), and near infrared (NIR) were used in this work. The different techniques did not evidently and systematically show that the treatment methods result in an increase of the silanol concentration. NMR measurements indicated that the relative amount of geminal silanols was decreased by the treatment and chromatographic measurements indicated that the relative amount of vicinal silanols was increased. The presence of water in the samples was the main problem in the qualification and quantification of silanol groups.}},
  author       = {{Lundin, Emma}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Development of a Surface Reduction Treatment Method of Amorphous Silica with High Porosity and Characterization of the Surface Chemistry}},
  year         = {{2015}},
}