photo catalytic
TRANSCRIPT
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PHOTOCATALYSTNguyen Thi Dieu Thuy, Chonbuk National University
October , 2015
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1) Photocatalys
2) Nanoparticles necessary for
photocatalyst with high activity
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CONTEXT
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Chlorophyll of plants is a
typical natural photocatalyst.
Chlorophyll captures sunlight
to turn water and carbondioxide into oxygen and
glucose.
In the presence of light and water,
Photocatalyst creates strong
oxidation agent and electronic
holes to breadown the organic
!atter to carbon dioxide and water
1. Photocatalyst
A photocatalyst is a substance that useslight energytofacilitate a
chemical reaction.
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Mechanism o !hotocatalysis
This cycle continues when light
is available.
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Basic Functions of Photocatalyst
a" #terili$ing %ect
Photocatalyst does not only ill bacteria cells, but also deco!pose thecell itself.
"he titaniu! dioxide photocatalyst has been found to be !ore effective
than any other antibacterial agent, because the photocatalytic reaction
wors even when there are cells covering the surface and while the
bacteria are actively propagating.
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b. Deodorizing effect
"he hydroxyl radicals accelerate the breadown of
any #olatile $rganic Co!pounds by destroying the
!olecular bonds.
"his will help co!bine the organic gases to for! a
single !olecule that is not har!ful to hu!ans thus
enhance the air cleaning efficiency.
Basic Functions of Photocatalyst
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7Applications of photocatalyst air purification
c. Air Purifying Effect
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d. Anti fogging, Self-Cleaning
%hen the original building !aterials are coated with a photocatalyst, a
protective fil! of titaniu! provides the self&cleaning building by beco!ing
antistatic, super oxidative, and hydrophilic.
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e. Water Purification
Photocatalyst coupled with UV lights can oxidize organic
pollutants into nontoxic materials, such as CO2 and water and
can disinfect certain bacteria.
This technology is very effective at removing further hazardous
organic compounds (TOCs) and at killing a variety of bacteria
and some viruses in the secondary wastewater treatment.
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Degradation of Dyes using TiO2
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TiO2 Degrading Methylene Blue
0 10 20 30 40 50 60 70
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1.1
1.2
1.3
1.4
1.5
1.6
Absorbance s. T ime
Time (mins)
Absorbance
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2. Nanoparticles necessary for photocatalyst with high activity
Quantum size efects on the nanoparticles properties. Thus byvarying the size o the semiconductor particles, it is possible toenhance the redox potential o the valence-band holes and theconduction band electrons.
Small size
The big surace area
Shape and size o
interactive surace
Adsorption potential
A goodphotocatalyst
ith highactivity
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THANK YOU
FORYOUR
ATTENTION