Multifunctional Ag/TiO2/MCM-41 nanocomposite film applied for indoor air treatment

Publication date: December 2014
Source:Building and Environment, Volume 82
Author(s): Waraporn Tongon , Chamorn Chawengkijwanich , Siriluk Chiarakorn
In this study, the indoor applications of Ag/TiO2/MCM-41 nanocomposite films were investigated under visible light. The coatings were prepared using a microwave-assisted sol–gel method, according to the following molar ratio: 1Ti(OC4H9)4: 18CH3CH2OH:0.5C5H8O2: 2H2O: 0.2HNO3: 0.1AgNO3: 2SiO2. The XRD characterisations and TEM images indicated the presence of anatase TiO2, Ag nanoparticles and mesoporous MCM-41 within the Ag/TiO2/MCM-41 nanocomposite films themselves. The results of UV–visible spectroscopy revealed a significant increase in both UV and visible light absorption when Ag and MCM-41 were incorporated into the TiO2 film. The water-contact angle measurements showed that the surface of the nanocomposite film exhibited superhydrophilicity, which is a desirable property in the self-cleaning process. The application of an Ag/TiO2/MCM-41 nanocomposite film for gaseous benzene removal was carried out in a simulated indoor air system. The photodegradation efficiencies were arranged in the order of Ag/TiO2/MCM-41 (55%) > Ag/TiO2 (28%) > TiO2 (15%), respectively. The photodegradation kinetics of gaseous benzene on Ag/TiO2/MCM-41 nanocomposite films matched accordingly with the first-order model. The kinetic constants of TiO2, Ag/TiO2 and Ag/TiO2/MCM-41 nanocomposite films, irradiated under visible light, were measured at 0.015, 0.025 and 0.135 h⁻¹, respectively. Their degradation rates were measured at 0.273, 0.609 and 6.321 g L⁻¹ h⁻¹, respectively. The antimicrobial activity of the Ag/TiO2/MCM-41 nanocomposite film against gram-negative Escherichia coli (E. coli) was evaluated under fluorescent lighting, following the JIS Z 2801:2000 standard. The percentage reductions (%R) of E. coli seeded onto TiO2 films and Ag/TiO2/MCM-41 nanocomposite films were measured at approximately 55% and 98%, respectively, under fluorescent lighting.

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