Effect of TiO2 Loading, Water Depth and Light Intensity on Photo-Disinfection Efficacy of Escherichia Coli O157:H7 Using TiO2 NP-Embedded Cellulose Acetate Film in Water

Highlights Photo-disinfection using TiO2 NP-embedded CA film showed great potential.TiO2 loading, water depth, and light intensity affected TiO2 photo-disinfection. Bacterial reduction can be predicted based on water depth and light intensity.Durability of the TiO2 NP-embedded CA film has been demonstrated. Photocatalysis disinfection has great potential for food and water safety applications. TiO2 NP-embedded cellulose acetate (CA) film has shown effectiveness in inactivating Escherichia coli (E. coli) O157:H7 in water. This study evaluated the effect of several operational parameters such as TiO2 load, light intensity, and water depth on photo-disinfection efficacy of TiO2 NP-embedded CA film. Effect of TiO2 load on photocatalysis disinfection efficacy was investigated by assessing the disinfection rate of the films at different TiO2 levels in inoculated water at a weak UV-A light intensity. The individual and interaction effects of light intensity and water depth on photocatalysis disinfection were evaluated using the response surface methodology (RSM). Based on a central composite design, 13 runs of experiments were conducted with the combination of the two factors at three levels. The effect of film size on photo-disinfection efficacy was also investigated. Results showed that CA film with a TiO2 load of 0.82 mg/cm2 yielded the highest disinfection rate. An empirical model was established to predict the effect of light intensity and water depth on bacterial reduction with a high coefficient of determination (R2 = 0.98). An increased water depth or a decreased light intensity reduced photo-inactivation efficacy. A 5 log reduction was achieved during a 3-h treatment at a light intensity of 1 mW/cm2 and water depth at 1.6 cm. The photo-disinfection efficacy of the film was not significantly (p>0.05) affected by film size. The CA film was able to maintain antimicrobial efficacy after four repeated uses. Results from this study demonstrated that UV-A assisted photo-disinfection using TiO2 NP-embedded CA film has great potential to inactivate pathogens in water. Keywords: Cellulose Acetate, E. coli O157:H7, Photocatalysis, TiO2 nanoparticles, Water Treatment.