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Enhancement of solar inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation
Author(s) -
Salih F.M.
Publication year - 2002
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2002.01601.x
Subject(s) - titanium dioxide , chemistry , photocatalysis , escherichia coli , water disinfection , energy conversion efficiency , cysteamine , chemical engineering , nuclear chemistry , materials science , biochemistry , environmental engineering , catalysis , environmental science , optoelectronics , engineering , gene
Aims: To improve solar water disinfection using a photocatalysing semi‐conductor and to study the mechanisms involved in this process. Methods and Results: Cells of Escherichia coli were used as the microbiological indicator to study the possibility of improving the efficiency of solar water disinfection using titanium dioxide (TiO 2 ) as a photooxidizing semi‐conductor. TiO 2 was used either as a suspended powder or in an immobilized form. Both applications improved the efficiency of solar disinfection. TiO 2 in suspension was more effective than the immobilized form, producing enhancement factors of 1·62 and 1·34, respectively. The concentration of TiO 2 greatly affected efficiency, with a maximum effect at 1 mg ml −1 . Higher TiO 2 concentrations reduced the efficiency. Dimethyl sulphoxide (DMSO) and cysteamine (Cys), hydroxyl radical (OH · ) scavengers, were used to elucidate the mechanisms involved in the presence of TiO 2 . Both DMSO and Cys totally abolished the enhancing effect produced by the presence of TiO 2 . Conclusions: Sunlight has a potential water disinfecting capacity. The use of TiO 2 greatly improved this efficiency. The effect of TiO 2 was mainly concentration‐dependent, giving maximum efficiency at 1 mg ml −1 . The presence of DMSO and Cys removed the TiO 2 ‐induced enhancement, indicating that OH · may be involved in the process of cell killing. Significance and Impact of the Study: The efficiency of solar disinfection is limited and time‐consuming and needs to be improved. The use of a semi‐conductor is promising as it reduces the time of exposure and therefore increases the efficiency of solar disinfection. This would allow for the availability of good quality water, and hence would improve the quality of life.