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...ion in a batch reactor was tested on Coliform. Bacterial sample was taken from polluted water and grown in lactose broth (Merck) on an orbital shaker at 35 ºC for 24 to 48 h until was gotten turbid. From this culture, sample was inoculated into EMB agar (Merck). Plates were incubated at 37 ºC for 24 h. Then for preparation of polluted water, a colony of culture produced in EMB agar was added to 1000 ml water. Most Probable Number (MPN) of Coliform in samples was measured as MPN/ 100 ml before, during and after examinations by using the fermentation technique in presumptive and confirmed tests (11, 15) TiO2 (Degussa P-25) was used as the photocatalyst in a batch-type reactor was a gift from Aeroxide (Evonik-Industries Germany). The sample used in this particular work had a BET surface area of 50±15 m2 g-1, an average particle diameter of 21 nm and the density was 130 g L-1. pH (Hach, Sension 5) adjustments in samples were made using 1 N HCl acid (Merck, 37%) and 1N NaOH (Merck 100%). UV source and light intensity A 40 W low pressure UV lamp, 0.8 m in length was installed 5 cm above the samples surface and the light intensity was 0.9 J s-1m-2 measured by a radiometer at 300 to 400 nm (Hagner...

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...ocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of photons, excites the electrons on the surface of titanium atoms suspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 Corresponding Author: Dr Mohammad Taghi Samadi, Fax: +98 811 8255301, E-mail: samadi@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surfa...

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...uspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 Corresponding Author: Dr Mohammad Taghi Samadi, Fax: +98 811 8255301, E-mail: samadi@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surface of titanium atom, and free electrons, which are now available to form hydroxide (OH) or other radicals, which can used as a powerful oxidizing agent to convert organic pollutants into CO2 or inactivated microorganisms (7, 9, 11, 13). The antimicrobial activity of UV/TiO2 has been essayed in several microbes including Enterobacter caloacae (12), Escherichia coli (2, 4, 8, 10-12, 14, 15), Pseudomonas aeruginosa (10, 12), Cyanobacteria and Unicellular algae (3), Lactobacillus helveticus (4), Legionella pneumophila (14), Clostridium perfringens and Coliphages (7). In this work, we have compared the effectiveness of TiO2, UV and UV/TiO2 for the disinfection of Coliform bacteria as a water microbial pollution index. Material and Methods Bacteria culture and TiO2 The effect of photocatalytic on disinfection in a batch reactor w...

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... bacteria such as Coliform. A new finding made in 1970 resulted in significant reevaluation of this long established disinfection practice was about disinfection by products. This disinfection by products, formed via the reaction between disinfectants and certain organic matters in water, may be harmful to human health. Thus, the new methods for decreasing the side effects of disinfectants must be improved (4-8). The application of photocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of phot...

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... bacteria such as Coliform. A new finding made in 1970 resulted in significant reevaluation of this long established disinfection practice was about disinfection by products. This disinfection by products, formed via the reaction between disinfectants and certain organic matters in water, may be harmful to human health. Thus, the new methods for decreasing the side effects of disinfectants must be improved (4-8). The application of photocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of phot...

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...formed via the reaction between disinfectants and certain organic matters in water, may be harmful to human health. Thus, the new methods for decreasing the side effects of disinfectants must be improved (4-8). The application of photocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of photons, excites the electrons on the surface of titanium atoms suspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 20...

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...di@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surface of titanium atom, and free electrons, which are now available to form hydroxide (OH) or other radicals, which can used as a powerful oxidizing agent to convert organic pollutants into CO2 or inactivated microorganisms (7, 9, 11, 13). The antimicrobial activity of UV/TiO2 has been essayed in several microbes including Enterobacter caloacae (12), Escherichia coli (2, 4, 8, 10-12, 14, 15), Pseudomonas aeruginosa (10, 12), Cyanobacteria and Unicellular algae (3), Lactobacillus helveticus (4), Legionella pneumophila (14), Clostridium perfringens and Coliphages (7). In this work, we have compared the effectiveness of TiO2, UV and UV/TiO2 for the disinfection of Coliform bacteria as a water microbial pollution index. Material and Methods Bacteria culture and TiO2 The effect of photocatalytic on disinfection in a batch reactor was tested on Coliform. Bacterial sample was taken from polluted water and grown in lactose broth (Merck) on an orbital shaker at 35 ºC for 24 to 48 h until was gotten turbid. From this culture, sample was inoculated into EMB agar ...

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...ace charge of E. coli has a negative charge character and J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 5 the TiO2 particle has a point of zero charge pH of about 6.3. Thus, it was expected that electrostatic repulsion between the TiO2 surface and Coliform at high pH would be higher due to their both having the same negative charge. However, such a trend was not observed. Although the electrostatic interaction at the TiO2/water interface could be important in many cases of photocatalytic degradation of charged substrates, it is a relatively weak force, which can be dominated by other factors (2, 13, 17). Effect of UV irradiation, TiO2 and contact time The effect of UV irradiation and TiO2 on removal of Coliform shows in Fig. 3. The experiments were done at initial 240000 MPN/ 100 ml, TiO2 concentration of 800 ppm and pH= 7.0. The experiments were continued up to 90 min. It is obvious that removal efficiency of Coliform in the absence of each of TiO2 or UV irradiation, with time was low, while in the presence of both of them, removal efficiency was increased. The 96% reduction time at an optimal concentration of 0.8 gr TiO2 L-1 was 10 min at 0.9 Js-1m-2. It can be concluded from these results...

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...formed via the reaction between disinfectants and certain organic matters in water, may be harmful to human health. Thus, the new methods for decreasing the side effects of disinfectants must be improved (4-8). The application of photocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of photons, excites the electrons on the surface of titanium atoms suspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 20...

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...ocatalysis in the treatment of water and wastewater is an interesting alternative and is the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of photons, excites the electrons on the surface of titanium atoms suspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 Corresponding Author: Dr Mohammad Taghi Samadi, Fax: +98 811 8255301, E-mail: samadi@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surfa...

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...uspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 Corresponding Author: Dr Mohammad Taghi Samadi, Fax: +98 811 8255301, E-mail: samadi@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surface of titanium atom, and free electrons, which are now available to form hydroxide (OH) or other radicals, which can used as a powerful oxidizing agent to convert organic pollutants into CO2 or inactivated microorganisms (7, 9, 11, 13). The antimicrobial activity of UV/TiO2 has been essayed in several microbes including Enterobacter caloacae (12), Escherichia coli (2, 4, 8, 10-12, 14, 15), Pseudomonas aeruginosa (10, 12), Cyanobacteria and Unicellular algae (3), Lactobacillus helveticus (4), Legionella pneumophila (14), Clostridium perfringens and Coliphages (7). In this work, we have compared the effectiveness of TiO2, UV and UV/TiO2 for the disinfection of Coliform bacteria as a water microbial pollution index. Material and Methods Bacteria culture and TiO2 The effect of photocatalytic on disinfection in a batch reactor w...

Citation Context

...s the object of a great interest over the last years by many researchers (9, 10). In these researches, attention has been drawn toward an alternative technique where the pollutants are degraded by irradiation suspension of metal oxide semiconductor particles such as TiO2 or ZnO (2, 4, 9). TiO2 is an excellent photocatalyst for complete mineralization of pollutants in water and wastewater. It has been known as a chemical that is non-toxic, insoluble in water, stable under UV radiation and comparatively cheap (6, 11). TiO2 is capable to be activated by UV-light with wavelengths less than 400 nm (6, 11, 12). Light energy from ultraviolet radiation (light) in the form of photons, excites the electrons on the surface of titanium atoms suspended in the contaminated water, moving them from the valence band to the conductance band. Original Article J Res Health Sci, Vol. 9, No. 1, 2009, pp. 1-6 Corresponding Author: Dr Mohammad Taghi Samadi, Fax: +98 811 8255301, E-mail: samadi@umsha.ac.ir Rahmani AR et al: Photocatalytic Disinfection of… 2 The result of this energy change is the formation of holes in the surface of titanium atom, and free electrons, which are now available to form hydroxide (OH) or ...

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...on of… 2 The result of this energy change is the formation of holes in the surface of titanium atom, and free electrons, which are now available to form hydroxide (OH) or other radicals, which can used as a powerful oxidizing agent to convert organic pollutants into CO2 or inactivated microorganisms (7, 9, 11, 13). The antimicrobial activity of UV/TiO2 has been essayed in several microbes including Enterobacter caloacae (12), Escherichia coli (2, 4, 8, 10-12, 14, 15), Pseudomonas aeruginosa (10, 12), Cyanobacteria and Unicellular algae (3), Lactobacillus helveticus (4), Legionella pneumophila (14), Clostridium perfringens and Coliphages (7). In this work, we have compared the effectiveness of TiO2, UV and UV/TiO2 for the disinfection of Coliform bacteria as a water microbial pollution index. Material and Methods Bacteria culture and TiO2 The effect of photocatalytic on disinfection in a batch reactor was tested on Coliform. Bacterial sample was taken from polluted water and grown in lactose broth (Merck) on an orbital shaker at 35 ºC for 24 to 48 h until was gotten turbid. From this culture, sample was inoculated into EMB agar (Merck). Plates were incubated at 37 ºC for 24 h. Then for ...