Correlation of Photocatalytic Bactericidal Effect and Organic Matter Degradation of TiO₂ Part I: Observation of Phenomena

Abstract

This study aims to investigate the correlation of the photocatalytic oxidation effect of decomposing organic matter and inactivating bacteria using two different TiO2 materials: a Degussa P25 powder film and a commercial TiO2 thin film. The destructed organic matter was formaldehyde and the test bacterium was E. coli (JM 109 strain). The decomposition tests and the bactericidal tests were carried out in a plate reactor and on the TiO2 surface, respectively. Observations indicate that there exists an apparent correlation between the two photocatalytic processes of decomposing formaldehyde and inactivating E. coli. However, it is essential to distinguish the exact driver for microbe inactivation, in which both UV light irradiation and reactive oxygen species reaction are directfactors of disinfection, and for organic matter, in which only reactive oxygen species reaction contributes to degradation. Observations from this study would make it possible to use analogy as a potential method to evaluate the antimicrobial effect based on the organic compound degradation effect, whereby the latter is much easier to measure quantitatively.

A ternary hybrid CdS/Pt–TiO2 nanotube structure for photoelectrocatalytic bactericidal effects on Escherichia Coli

“…The photoelectrocatalysis process was the fastest among these processes, indicating that the applied bias potential inhibited the recombination of the photogenerated electron-hole pairs effectively and prolonged the photogenerated the life of charge carriers [45]. In order to compare the effects with variable conditions, the results were evaluated by inactivation rate constant k of the Click model; one of the most commonly used models for TiO 2 inactivation kinetics of microbes [58,59]. The model is expressed by the following equation:…”

Preparation of epoxy-acrylate copolymer@nano-TiO2 Pickering emulsion and its antibacterial activity

“…Nano-TiO 2 with self-cleaning property [17], high surface activity [18,19] and low cost [20] is of critical inorganic nanoparticles for development of superior composite materials. Its photocatalysis and nontoxicity make it widely use in lithium ion battery [21], optical catalyst [22,23] and antibacterial function coatings [24,25]. Nano-TiO 2/ polyurethane composite emulsion for antibacterial and self-cleaning coatings could be synthesized by the "grafting from" polymerization method [26].…”

In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts

“…Anatase shows excellent photoactivity and has been used in catalysis of photoinduced advanced oxidative processes and in destroying various pollutants in water, aqueous solutions, and air [11][12][13]. This photocatalytic properties have also been exploited in destroying bacteria [14,15] or in improving the efficacy chemotherapy [16].…”