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Natural dye-sensitized ZnO nano-particles as photo-catalysts in complete degradation of E. coli bacteria and their organic content

Paper ID Volume ID Publish Year Pages File Format Full-Text
25935 43920 2016 10 PDF Available
Title
Natural dye-sensitized ZnO nano-particles as photo-catalysts in complete degradation of E. coli bacteria and their organic content
Abstract

•Natural dye anthocyanin sensitizes ZnO particles to visible light in phot-catalytic processes.•ZnO/Dye kills E. coli bacteria and completely mineralizes its organic content under solar simulator light.•ZnO/Dye catalyst can be recovered and re-activated by re-sensitizing with dye.

This communication describes for the first time how nano-size particles, sensitized with natural dye molecules of anthocyanin, can be used as catalysts in photo-degradation of gram negative Escherichia coli bacteria in water. The naked ZnO nano-particles degraded up to 83% of the bacteria under solar simulator light, while the dye-sensitized particles increased the bacterial loss by ∼10%. Solar simulator light includes about 5% of UV tail (shorter than 400 nm) which means that both UV and visible light (longer than 400 nm) radiations could be involved. When a cut-off filter was used, the naked ZnO caused only 40% bacterial loss, in accordance with earlier literature that described killing of bacteria with ZnO particles both in the dark and under light. With the cut-off filter, the sensitized ZnO particles caused higher than 90% bacterial loss, which confirms sensitization of the ZnO particles to visible light. Moreover, the results show that the catalyzed photo-degradation process causes mineralization of the bacteria and their organic internal components which leach out by killing. The catalyst can be recovered and reused losing ∼10% of its activity each time due to mineralization of the dye molecules. However, catalyst activity can be totally regained by re-sensitizing it with the anthocyanin dye. The effects of different experimental conditions, such as reaction temperature, pH, bacterial concentration and catalyst amount together with nutrient broth and saline media, will be discussed together with the role of the sensitizer.

Graphical abstractSchematic showing how anthocyanin-sensitized ZnO particles catalyze solar disinfection processes.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Photo-degradation; ZnO nano-particles; Anthocyanin sensitizer; E. coli; Mineralization
First Page Preview
Natural dye-sensitized ZnO nano-particles as photo-catalysts in complete degradation of E. coli bacteria and their organic content
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 328, 1 September 2016, Pages 207–216
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering