สมเจตน์ โพธิ์ทอง. Preparation and Characterization or Amine-functionalized SiO2/TiO2 Thin Film Photocatalyst for Gaseous Formaldehdehy Photoxatalytic Degradation . Doctoral Degree(Chemical Engineering). King Mongkut's University of Technology Thonburi. KMUTT Library.. : King Mongkut's University of Technology Thonburi, 2009.
Preparation and Characterization or Amine-functionalized SiO2/TiO2 Thin Film Photocatalyst for Gaseous Formaldehdehy Photoxatalytic Degradation
การเตรียมและการวิเคราะห์สมบัติของ Amine-functionalized SiO2 TiO2 Thin Film Photocatalyst ที่ใช้สำหรับสลายแก๊สฟอร์มัลดีไฮด์ด้วยปฎิกิริยาการสลายตัวโดยใช้แสงเป็นตัวเร่ง
Abstract:
The aim of this thesis was to synthesize the amine-functionalized SiO2 TiO2
photocatalytic film for gaseous formaldehyde degradation. The films were synthesized
via the co-condensation reaction of amine functional group precursors and
methyltrimethoxysilane (MTMOS). Amorphous TiO2, powder (P25) and peroxo titanic
acid retluxed solution (PTA) v\ere selected as TiO2 sources.
Firstly, n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS) and
3-aminopropyl-trimethoxysilane (APTMS) were used to fabricate the amine functionalized
SiO2/TiO2, film by using amorphous TiO2 (P25) calcined at various
temperatures as a TiO2 source. The results indicated that the APTMS-functionalized
SiO2/TiO2 film demonstrated the degradation efficiency of 79(% superior to those of
SiO2/TiO2, and AEAPTMS-functionalized SiO2/TiO2 films due to the surface adsorption
on amine sites and the relatively high specific surface area of the APTMS-functionalized
SiO2/TiO2 film (-15 times higher than that of the SiO2:TiO2 film). The
enhancement of the formaldehyde degradation of the film can be attributed to the
synergetic effect of adsorption and subsequently photocatalytic decomposition. In
addition, the adsorption and the photocatalytic efficiencies or the APTMS functionalized
SiO2/TiO2 film prepared with the APTMS/MTMOS molar ratio of 0.03
is better than that of bared SiO2/TiO2. AEAPTMS-functionalized SiO2:TiO2 and the
others APTMS/MTMOS molar ratio of APTMS doping films. The APTMS functional
group directly affected the silicate network formation and the specific surface area of
the prepared photocatalysts. The APTMS doping film prepared with the
APTMS/MTMOS molar ratio of 0.03 possesses the highest specific surface area of
402.40 m2g-1.
Secondly. the transparency of the APTMS-functionalized SiO2/TiO2 film was improved
by using peroxon titanic acid refluxed solution (PTA) as a TiO2, source instead of TiO2
powder since the powder form of TiO2 allected thc transparency or the film. The
transparency is one of the expected characteristic of the photocatalytic film because it
can enhance light transmittance resulting in an increasc of degradation efficiency.
Moreover due to the transparent property of the film. it could be applied as a coated glass
for practical use or ambient air purification. In this part. thc amine-functionalized
SiO2/TiO2, transparent film was synthesized using the peroxo titanic acid (PTA) refluxed
method as TiO2 preparation route together with a modified sol-gel method. The effects
of the APTMS/MTMOS molar ratio. PTA reflux time. and pH of the prepared sol on the
characteristics as well as the formaldehyde degradation efficiency of the film were
investigated. The obtained films showed good transparency with the transmittance of
80-90% in the visible light region. The film prepared with the APTMS/MTMOS ratio of
0.03. pH of 1.8 and 10 h of reflux time demonstrated the highest specific surface area of
604.0 m2g- 1 and 85% degradation efficiency.
Finally the repeatability of the APTMS-functionalized SiO2/TiO2 film
(APTMS/MTMOS =0.0.3 TiO2 calcined at 500 C) and the APTMS-functionalized
SiO2/TiO2 transparent film (10 h-pH 1.8), which had the highest formaldehyde
degradation efficiency were tested in order to apply the coated film for practical use.
After seven cycles, the formaldehyde degradation efficiencies of the former and the
latter films were 91 % and 92% of their initial efficiencies, respectively.