Development of nanosized TiO2 powder photocatalyst and its application for bacteria killing /
Titanium dioxide represents an effective photocatalyst for water and air purification and for disinfection of microorganism due to its potential to attack chemical species. TiO2-anatase is the most widely used photocatalyst; it is a wide bandgap (3.2 eV) semiconductor which, under UV illumination, i...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur:
Kulliyyah of Engineering, International Islamic University Malaysia,
2011
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | Titanium dioxide represents an effective photocatalyst for water and air purification and for disinfection of microorganism due to its potential to attack chemical species. TiO2-anatase is the most widely used photocatalyst; it is a wide bandgap (3.2 eV) semiconductor which, under UV illumination, is able to degrade chemicals and cell components of microorganisms. Nanosized TiO2 powder photocatalyst was synthesized by sol-gel method using titanium metal alkoxide, titanium diisopropoxide (PTP) as the precursor. Reflux time was varied in order to get uniform nanosized TiO2 particles. XRD analysis confirmed that the TiO2 powders A (15 minutes reflux) and B (1 hour reflux) have highest peak at 25° in 2θ which indicated anatase crystal structure. The particle size of powder A was smaller than the powder B as proved by XRD result which was calculated via Scherrer's equation. The crystallization temperature of TiO2 powder A was higher owing to its smaller particles that needed more heat to crystallize than powder B as confirmed by Thermogravimetric and Differential Thermal Analyzer (TG/DTA). From Field Emission Scanning Electron Microscope (FESEM) analysis, powder A showed homogenous spherical shape while powder B showed nonhomogenous spherical shape and agglomerated particles. The photocatalytic degradation of E. coli was investigated by UV irradiated TiO2 sol-gel powders and commercial Degussa P25. Photocatalytic performance was tested by varying the TiO2 concentration and UV intensity. Bacterial inactivation shows direct relationship with UV intensity. Therefore, no bacteria killing observed in the dark condition. When UV intensities increased, E. coli inactivation increased. Both TiO2 powders, demonstrated a decrease in cell survival with increasing catalyst concentration after 5 hours exposure under UV irradiation. The optimum catalyst concentration is 2.5 mg/ml, which is sufficient to absorb all photons and kill the bacteria. However, TiO2 concentration higher than 2.5 mg/ml resulted in an increase in cell survival due to access of UV light to the particle and access of particle to E. coli decreased. Therefore, as the maximum cell photocatalyst contact has been accomplished, excess of TiO2 did not increase the bacteria disinfections effect. |
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| Item Description: | Abstract in English and Arabic. "A dissertation submitted in fulfilment of the requirement for the degree of Master of Science (Materials Engineering)."--On t.p. |
| Physical Description: | xvii, 110 leaves : ill. ; 30cm. |
| Bibliography: | Includes bibliographical reference (101-108). |