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‘TiO 2 ’, GREEN CATALYST: CLEAN ENVIRONMENT - ppt slideshow


Introduction. Photocatalysis - Need of the day . . Photocatalysis. . . Photocatalytic Applications. Antimicrobial Effect. . Antimicrobial Effect. . Self-Cleaning Effect. . . . . Photocatalysts. TiO2

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TiO2 , GREEN CATALYST: CLEAN ENVIRONMENT

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‘TiO2’, GREEN CATALYST: CLEAN ENVIRONMENT

Dr. Romana Khan

Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad

1st National Conference on Biotechnology & Microbiology


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Introduction

Photocatalysis - Need of the day


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CO2 + H2O

CO2

Chlorophyll

Photocatalyst

Organic

Compound

+ H2O + O2

H2O

Starch + O2

Organic compound

Photocatalysis


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Photocatalytic Applications


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Antimicrobial Effect


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Antimicrobial Effect


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Self-Cleaning Effect


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Photocatalysts


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TiO2 – an Ideal Photocatalyst

  • Cheap and can be reused

  • High photo-chemical corrosive resistance

  • Strong oxidizing power

  • Photocatalysis takes place at ambient temperature

  • Atmospheric oxygen is used for the reaction


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TiO2 - Photocatalysis

3.12 eV (380 nm)


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Redox potential of h+

  • The redox potential for photogenerated h+ is +2.53 V vs. the SHE

  • After reaction with water, these h+ can produce •OH

  • Both h+ and •OH are more positive compare to ozone


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Photocatalytic Reactions


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Entail Physicochemical Properties of TiO2

The applications of TiO2 is a function of specific physicochemical properties like:

  • High Surface area

  • Small Crystalline Size

  • Anatase form of TiO2

  • High crystallinity

  • Porous structure

  • Activation light source

    An appropriate synthetic procedure can provide TiO2 with promising efficiency


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Synthesis of TiO2 Powders

Synthesis of TiO2 powders

  • Sulfate Method

  • Chloride Method

  • Specific Methods

  • Sol-Gel Method


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Hydrolysis and Condensation


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Sol-Gel Technology


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Visible-Light Active Photocatalyst

TiO2– efficient photocatalyst under UV light

Yet, need visible-light active photocatalyst for practical purpose

Can be achieved by doping TiO2 with nonmetals, transition metals and dyes

Activity increases by loading a metaloxide

Metal oxide reduces the chance of recombination of electrons & holes produced during photocatalytic reactions


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Modification of TiO2


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Coating Techniques

A- Spin Coating Method


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B- Dip Coating Method


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C-Spray Coating Method


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Setting SubstratesVacuumingCoating/ Discharging plasmaCollecting Substrates

D- Sputtering Method


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E- Plate Coating


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An Acid-Base Catalyzed Sol-Gel Synthesis of TiO2 Photocatalysts

Ti(OBu)4 + EtOH

HCl + H2O + EtOH

Stirring (12 h)

Sol (pH 0.8)

Stirring (12 h)

NH4OH

Gel (pH 9.0 )

Drying (1100C, 12 h)

Calcination


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Phase Structure and Thermal Stability

XRD patterns of TiO2 samples; (a) as-dried, and calcined at (b) 350 oC, (c) 400 oC, (d) 500 oC, (e) 600 oC and (f) 800oC.


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Some Selected Properties of TiO2 Powders


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Photocatalytic Efficiency

  • Catalytic degradation of toluene by different TiO2 samples;

  • Blank (■)(b)TiO2 – as-dried (●); (c) P-25 (▲); and TiO2 calcined at

  • (d) 350oC (▼); (e) 400oC () (f) 500oC (◄ ); (g) 600oC (►).


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Photoreactor


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Publications

  • Romana Khan, S.W. Kim, T.J. Kim, H.S. Lee – A novel acid-base catalyzed sol-gel synthesis of highly active mesoporous TiO2 photocatalysts, Bulletin of the Korean Chemical Society, 28(11), 1951-1957 (2007).

  • Romana Khan, S.W. Kim, T.J. Kim – Synthesis and control of physical properties of titania nanoparticles as a function of synthetic parameters, Journal of Nanoscience and Nanotechnology, 8(9), 4738-4742 (2008).

  • Romana Khan, S.W. Kim, T.J. Kim, C.M. Nam – Comparative study of the photocatalytic performance of boron–iron co-doped and boron-doped TiO2 nanoparticles, Materials Chemistry and Physics, 112(1), 167-172 (2008).

  • Romana Khan, S.W. Kim, T.J. Kim, C.M. Nam – Comparative study of the photocatalytic performance of boron–iron co-doped and boron-doped TiO2 nanoparticles, Materials Chemistry and Physics, 112(1), 167-172 (2008).

  • Romana Khan, T.J. Kim – Preparation and application of visible-light responsive Ni-doped and SnO2-coupled TiO2 nanocomposite photocatalysts, Journal of Hazardous Materials, 163(2-3), 1179-1184 (2009).


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Thank You