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Abstract
Photocatalytic disinfection using TiO2 nanoparticles is a promising approach to reduce foodborne pathogens and enhance food safety. The overall goal of this research was to develop a TiO2 nanoparticle (NP)-embedded polymer film and to assess its antimicrobial efficacy. A protocol for fabricating TiO2 NP-embedded polymer film was developed in the first study. TiO2 NP-embedded films using three different biodegradable polymers were fabricated and evaluated on their optical, morphological, photocatalytic, and antimicrobial properties. TiO2 NP-embedded CA film showed the highest bactericidal effectiveness and good physical property. In the second study, photocatalytic disinfection efficacy of TiO2 NP-embedded CA film was evaluated using different testing methods that simulate practical application scenarios. Results showed that the antimicrobial performance of TiO2 NP-embedded CA film varied depending on application scenarios. The most effective applications of TiO2 NP-embedded polymer film can be obtained when in direct contact with liquid inoculum or contaminated solutions. In the third study, the effect of the operational parameters including TiO2 load, light intensity, and water depth on the photo-disinfection efficacy of TiO2 NP-embedded CA film was evaluated through a systematic approach. An optimum TiO2 concentration was identified at 0.82 mg/cm2. Response surface methodology yielded a model to predict the disinfection efficacy of TiO2 NP-embedded CA film as functions of the water depth and light intensity. Photo-disinfection efficacy of TiO2 NP-embedded CA film can be maintained when the film area expanded. The photo-disinfection efficacy did not change significantly (p ≥ 0.05) after four repeated usages. In the last study, the effect of natural water compounds such as humic acid, CaCO3, and kaolin clay on photo-disinfection efficacy of TiO2 NP-embedded polymer film in water was evaluated. Humic acid showed the highest inhibition effect against photo-disinfection, followed by CaCO3 and kaolin clay. Water quality analysis showed that UVT-254 and water hardness had the highest correlation with the inhibition effect of water compounds on the water photo-disinfection efficacy. A prediction equation was developed with UVT-254 and water hardness as independent variables to predict photo-disinfection efficacy in natural water. The overall findings of this project showed TiO2 NP-embedded polymer film has great potential for enhancing water safety.