Abstract

In this study, photocatalytic degradation of methylene blue was examined using different concentrations of TiO 2 nano-particles (diameters less than 21 nm) and ultraviolet (UV-C) radiation in a tubular reactor. Different concentrations of catalyst (0.3-1.2 g/L), different pH conditions (3, 7 and 9) and dye concentration (15, 30 and 60 mg/L) as well as sample rotation level (125 mL/min) were studied. The sample passed 1-7 times through the quartz reactor exposed to UV-C ray (constant intensity = 2.8 mW/cm 2) (every rotation time was 8 min). Results of this research showed clearly that methylene blue is significantly degradable by TiO 2 and UV-C radiation. Increasing dye concentration resulted in decreased efficiency and thus, as more samples passed through quarts tube, removal efficiency increased. Methylene blue with concentration of 15 mg/L and after 7 rotations in the reactor (56 min) was removed with the efficiency of 98. Subsequent to dye removal, 47 of initial COD decreased simultaneously.