Photocatalytic Disinfection of Bacteria by Sodium Light with Smectite Catalysts
| Autor: | Chiu-Jung Liao, Shu-Lung Kuo |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | Water Quality Research Journal. 41:365-374 |
| ISSN: | 2408-9443 1201-3080 |
| Popis: | In this study, modifications of Wyoming smectite clay minerals are conducted using four types of metallic cations that cover the surface with Ag+, Zn2+, Ti4+ and Ag+/Zn2+ to form smectite catalysts and destroy bacteria. When the smectite catalysts are illuminated with a sodium lamp, they reduce the number of viable bacteria in surface water and achieve a disinfecting effect. On the whole, smectite-Ti catalysts have the best disinfection efficiency, followed by coupled smectite-Ag/Zn catalysts, smectite-Ag catalysts and smectite-Zn catalysts. The higher quantity of catalysts there is, the easier it is for the shielding effect to take place. This causes a lower intensity of sodium light to react with the bacteria. When smectite-Zn catalysts are in the catalytic process, they produce intermediates that can compete for reaction sites with the OH free radicals. This can reduce the production of electrons and holes, and hence the reaction rate of objects on the surface of smectite-Zn catalysts. In smectite-Ag/Zn catalysts, coupled catalysts combine two types of semiconductor catalysts that have different energy gaps and energy band sites. These can separate electrons and holes more efficiently, increase the lifetime of electron carriers, and enhance disinfection efficiency. This study utilizes factor analysis of multivariate analysis to discuss the correlations between different catalysts, e.g., the four types of smectite catalysts and catalysts with different weight percentages, respectively. The results show two findings: (1) there is only one main factor influencing the disinfection efficiency of the four types of smectite catalysts—the photocatalytic competitiveness factor; and (2) only one main factor affects the disinfection efficiency of the four types of catalysts with different weight percentages—the concentration shielding effect factor. |
| Databáze: | OpenAIRE |
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