‘TiO 2 ’, GREEN CATALYST: CLEAN ENVIRONMENT

1. ‘TiO2’, GREEN CATALYST: CLEAN ENVIRONMENT Dr. Romana Khan Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad 1st National Conference on Biotechnology & Microbiology

2. Introduction Photocatalysis - Need of the day

3. CO2 + H2O CO2 Chlorophyll Photocatalyst Organic Compound + H2O + O2 H2O Starch + O2 Organic compound Photocatalysis

4. Photocatalytic Applications

5. Antimicrobial Effect

6. Antimicrobial Effect

8. Self-Cleaning Effect

9. Photocatalysts

10. 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

11. TiO2 - Photocatalysis 3.12 eV (380 nm)

12. 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

13. Photocatalytic Reactions

14. 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

15. Synthesis of TiO2 Powders Synthesis of TiO2 powders • Sulfate Method • Chloride Method • Specific Methods • Sol-Gel Method

16. Hydrolysis and Condensation

17. Sol-Gel Technology

18. 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

19. Modification of TiO2

20. Coating Techniques A- Spin Coating Method

21. B- Dip Coating Method

22. C-Spray Coating Method

23. Setting SubstratesVacuumingCoating/ Discharging plasmaCollecting Substrates D- Sputtering Method

24. E- Plate Coating

25. 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

26. 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.

27. Some Selected Properties of TiO2 Powders

28. 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 (►).

29. Photoreactor

30. 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).

31. Thank You