Photocatalytic mechanism of action of apatite-coated Ag=AgBr=TiO 2 on phenol and Escherichia coli and Bacillus subtilis bacteria under various conditions

Elahifard, M. R. (Mohammad Reza) ; Sharif University Of Technology

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  1. Type of Document: Article
  2. DOI: 10.3184/146867810x12925913885187
  3. Abstract:
  4. Multi-component photocatalysts based on apatite-coated Ag/AgBr/TiO(2) were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-static. The mechanism for deactivation of bacteria in the dark can be related to the linkage between the phosphate group of the composite and the outer membrane of the cell. The photocatalytic destruction of bacteria under visible light indicates that attachment of the catalysts to the outer wall of the cell causes them to destroy effectively the cell wall and inner membrane by various reactive species such as (center dot)OH, O2(center dot-) and (1)O(2). Thus this effect increases the photoactivity more than two-fold. Oxidation of phenol was also achieved under visible light-and UVA-irradiation using apatite-coated Ag/AgBr/TiO(2) powders. UnderUVAillumination, the (center dot)OH produced from the hole of the TiO(2) valence band is responsible for the photodegradation of phenol, while under visible light, AgBr acts as the photoactive component of the catalyst, that can not produce (center dot)OH and oxidize the phenol
  5. Keywords:
  6. Bacillus subtilis ; Cell walls ; Bacteria-static ; Escherichia coli ; Photocatalyst ; Apatite ; Deposition methods ; Different mechanisms ; Growth of bacteria ; Inner membranes ; Mechanism of action
  7. Source: Progress in Reaction Kinetics and Mechanism ; Vol. 1 , Vol.36 (1) , 2011 , pp.38-52
  8. URL: http://www.ingentaconnect.com/content/stl/prk/2011/00000036/00000001/art00004?token=004b1196b6720297d76345f7b744a6c246c425957206d3f6a4b4b6e6e42576b64273806f977