The problem of bacterial infection causes serious impacts in the economy and environment. In addition, the development of the circular economy has drawn considerable attention. The great amount of agriculture waste, shrimp shells, can be transformed into safe antibacterial agents. Chitosan (CTS) [poly (b-(1→4)-2-amino-2-deoxy-D-glucose)] is the N-deacetylated derivative of chitin. CTS has a wide range of applications and beneficial properties including antifungal and antibacterial. The incorporation of nano-materials, such as nano- Titanium dioxide (TiO2) into natural biopolymer has been proven to improve the mechanical properties. TiO2 is an outstanding photocatalyst due to its photo-disinfection activity, high chemical/physical stability, cost efficiency, and environmentally friendly. Carbon-doped TiO2 (C-TiO2) synthesized by our research group show high photo-disinfection efficiency under visible light. We hypothesis that the incorporation of shrimp-shells-CTS into C-TiO2 will enhance photo-disinfection capacity with the synergy effect of CTS. The CTS-C-TiO2 composite will be used in this study. The photo-disinfection kinetic model experiments are conducted under various key parameters, such as bacteria species effect (Gram-positive bacteria, S. aureus and Gram-negative bacteria, E. coli), visible-light intensity effect, dosage effect, and initial bacteria concentration effect. Physical/chemical characteristics of CTS are evaluated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Photo-disinfection mechanism of bacteria is investigated via SEM and transmission electron microscope (TEM) technology for morphologies of bacteria cell in the photo-disinfection process. The characteristic results showed that the CTS synthesis from shrimp shell had two broad peaks at 2θ=10.3 and 20.0 degree. The FTIR spectrum of CTS had a broad band of about 3200–3374 cm−1 to show the stretching vibration of OH and NH groups. Antibacterial experiment results showed that CTS exhibited high antibacterial rate against E. coli and S. aureus achieved 99.9% within 2 hour reaction time. The novel CTS-C-TiO2 photocatalyst is equipped with excellent antibacterial activity against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. CTS-C-TiO2 is advantageous for addressing the problem of abundance agriculture waste and keeping human health with the synergy effect of CTS and nano-material.

Characteristics and photocatalytic disinfection performance of chitosan-C-doped TiO2 composite

256th National Meeting (2018)

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