Water Disinfection Using Chitosan Microbeads With N-, C-, C-N/TiO2 By Photocatalysis Under Visible Light.

Chitosan microbeads with C-doped TiO₂, N-doped TiO₂ and C,N-codoped TiO₂ were prepared to obtain photocatalysts with higher photocatalytic efficiency, active under visible light and easy to removed from aqueous medium. TiO₂ powders were synthesized by the sol–gel method and modified using glucose and ammonium nitrate as source of C and N, respectively. Scanning electron microscope (SEM), X-ray diffraction (XRD), DRUV–Vis spectra and Raman techniques, were used to characterize the modified TiO₂ powders. The structural and physicochemical properties of the microbeads were analyzed by nitrogen physisorption, functional groups were identified by Fourier transform Infrared (FT-IR) spectroscopy and microbeads were observed by optical microscopy. The microbeads photocatalytic efficiency under visible light was evaluated monitoring the E. coli growth-inhibition, determined by colony count analysis (CFU—colony forming units). Results showed effectiveness in all tested composites to inhibit E. coli growth in 24 h under visible light. Furthermore chitosan microbeads with C,N-codoped TiO₂ showed the best performance in the degradation test being the most effective composite to achieving 99.99% of E. coli growth inhibition in less than 4 h. [ABSTRACT FROM AUTHOR]