Abstract
(English)
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PHOTOCATALYTIC DEGRADATION OF WATER ORGANIC POLLUTANTS
Photocatalytic oxidation is a promising technology for the no only for detoxification but also for disinfection of water and wastewater. When catalytic semi-conductor powders, such as titanium dioxide, (TiO2) are suspended in water and irradiated with near UV (l< 385 nm), OH. free radicals are generated. The OH. radical is highly toxic towards microorganisms and very reactive in the oxidation of organic substances thus, photocatalytic inactivation of bacteria Escherichia coli, Bacillus pumilus and spores of Clostridium perfringens, as well as of virus Phage QB? have been investigated[1-3].
This study focuses on the photocatalytic bacterial inactivation with a solar-simulating lamp as the source of light. E. coli was selected as tested bacteria because of its common use as biological indicator of disinfection efficiency in water systems. The reactions were carried out in a batch type photoreactor using nanocrystalline TiO2 (P-25 of Degussa) as photocatalyst.
The synergistic effect of 'sunlight' irradiation and TiO2 catalyst on bacterial viability has been observed in previous works using Milli-Q water as a solvent [4]. Photocatalytic process was found to be highly influenced by the variations of parameters such as light intensity, catalyst concentration, initial bacterial concentration and the presence of organic matter.
If a real system consisting of water from natural origin is to be studied for disinfection by photocatalysis using TiO2, the previous parameters should be carefully adjusted in order to obtain the best conditions for such a process.
[1] Huang Z., P. Maness, et al., (2000), Bactericidal mode of titanium dioxide photocatalysis. J. Photochem Photobiol A. 130, 163.
[2] P. C. Maness, S. Smolinski, et al., (1999), Bactericidal Activity of Photocatalytic TiO2 Reaction: toward Understanding of its Killing Mechanism. Applied and Environmental Microbiology, 65 (9): 4094.
[3] Rincón A.G. Adler N, et al., (2001), Interaction between E.coli inactivation and DBPs precursors- in the photocatalytic process of drinking water with TiO2. J Phochem and Photob A. 139 (2-3): 233.
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