Photocatalytic degradation of methylene blue and inactivation of pathogenic bacteria using silver nanoparticles modified titanium dioxide thin films

World J Microbiol Biotechnol. 2015 Jul;31(7):1049-60. doi: 10.1007/s11274-015-1855-9. Epub 2015 Apr 16.

Abstract

Titanium dioxide (TiO2) is a well-studied photocatalyst that is known to break down organic molecules upon ultraviolet irradiation. TiO2 thin films were fabricated on glass substrates using the doctor-blade procedure, the film surface was modified with silver nanoparticles to increase its visible light response. The Ag-TiO2 films were characterized by transmission electron microscopy, scanning electron microscopy equipped with energy dispersive spectrometry and X-ray diffraction. The photocatalytic degradation of methylene blue (MB) and inactivation of Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus were studied. The modified films presented enhanced photocatalytic efficiency and can decompose MB solution two-times faster than the unmodified TiO2 films, under illumination of sunlight. A nominal degradation (15 %) was observed in control MB under sunlight. The degradation efficiency of Ag-TiO2 films slightly decreased after five consecutive experiments. Ag-TiO2 films revealed very effective bactericidal activity against both E. coli and S. aureus. The photocatalytic inactivation toward E. coli and S. aureus showed a similar trend with much higher effectiveness toward E. coli under the same experimental conditions. The inactivation efficiency was maximized and reached 95 % for S. aureus and 97 % for E. coli, after 180 min incubation. These results demonstrate the potential of application of Ag-TiO2 photocatalysis as a method for treatment of diluted waste waters in textile industries.

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology
  • Catalysis
  • Escherichia coli / drug effects*
  • Metal Nanoparticles / chemistry
  • Methylene Blue / chemistry*
  • Photochemical Processes
  • Silver / chemistry*
  • Staphylococcus aureus / drug effects*
  • Surface Properties
  • Titanium / chemistry
  • Titanium / pharmacology*

Substances

  • Anti-Bacterial Agents
  • titanium dioxide
  • Silver
  • Titanium
  • Methylene Blue