Asia Pacific Environmental and Occupational Health Journal

Introduction: Titanium dioxide (TiO2) as a photocatalyst produces oxidizing radicals for water treatment. Treatment performance of TiO2 in natural light will be improved when doped with nitrogen. This is because the bandgap energy of TiO2 will be lowered while its visible light absorbance will be increased.

Objective: To investigate the effects of nitrogen concentration on the photocatalytic behavior for TiO2 particles synthesized via sol-gel method.

Method: TiO2 and nitrogen-doped TiO2 (N-TiO2) powders were synthesized via sol-gel method. Calcination at 773 K followed by ball milling were done to obtain the TiO2 powders. The effect of nitrogen concentration on the photocatalytic performance of TiO2 was studied by varying the ratio of TTIP to urea. A filtration system was set up by incorporating TiO2 powders with filter paper to obtain the optimum parameters for degrading methylene blue and treating bacteria-contaminated water. Characterizations of the synthesized powders include ultraviolet-visible (UV-vis) light spectroscopy, dynamic light scattering (DLS) measurement and scanning electron microscopy (SEM).

Result: Nitrogen doping in TiO2 changes the appearance of powders from white to pale yellow. N-TiO2 with TITP:urea of 1:2 has the lowest bandgap energy of 2.740 eV. However, TTIP:urea of 1:3 yields the highest visible light absorbance (VLA) and the smallest average particle size at 425 nm with the least polydispersity.

Conclusion: The optimum setup for removing methylene blue is by using N-TiO2 with TTIP:urea ratio of 1:2 with 16 layers of filter paper which gives 98.42% methylene blue reduction. However, N-TiO2 with TTIP:urea of 1:3 gives the optimum antibacterial performance with 65.26% less bacterial coverage.