| Summary: | 碩士 === 國立東華大學 === 材料科學與工程學系 === 101 === The photocatalytic inactivation of E. coli under visible light irradiation over two
series (K4Nb6O17 and TiO2) of photocatalyst thin films and the effects of loading
silver nanoparticles as cocatalyst for the photokilling of E. coli were investigated.
First, K4Nb6O17 photocatalysts were prepared by a solid state reaction.
Then, K4Nb6O17 nanosheets (NS-K4Nb6O17) were prepared by exfoliation of
H+-exchanged layered niobates with tetrabutylammonium hydroxide (TBAOH). The
K4Nb6O17 nanosheets can be obtained via further ion-exchange reaction with KOH
solution.
Second, mesoporous TiO2 photocatalysts and TiO2 nanowires were prepared. The
mesoporous TiO2 were prepared by titanium isopropoxide (TTIP) as starting material
and triblock copolymer P123 as template. The TiO2 nanowires were prepared by
electrospinning method. Further, the photocatalyst films were prepared by
electrophoretic deposition. Then, Ag nanoparticles were loading to the photocatalyst
films by photoreduction and microwave reduction method.
The catalysts were studied using powder X-ray diffraction (XRD), transmission
electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), and scanning
electron (SEM).
In this study, we preformed the antibacterial activity test on theses photocatalyst
films according to JIS Z 2801:2000. The K4Nb6O17 photocatalyst films showed a
higher photocatalytic antibacterial activity than the TiO2 photocatalyst films. After
loading Ag nanoparticles, significant enhancing effects in photocatalytic inactivation
of E. coli. were observed on both K4Nb6O17 and TiO2 photocatalysts. The TEM
identification results showed that well dispersed Ag nanoparticles can be synthesized
by reduction of AgNO3 with PVP protection under microwave irradiation (in
approximately 90s microwave heating). On the other hand, Ag particles prepared by
photoreduction method showed a larger particle size of Ag nanoparticles than that
prepared by microwave reduction method. In this study, the 0.5wt% Ag / NSK4Nb6O17
catalyst exhibited the best antimicrobial activity, which eliminated > 99%
of bacteria in 45 min under visible light irradiation.
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