Photo-decolorization and detoxification of toxic dyes using titanium dioxide impregnated chitosan beads

The removal of three different dyes namely Reactive Red 2 (RR), Methylene Blue (MB) and Rhodamine B (RB) using titanium dioxide impregnated chitosan beads (TCB) by photocatalytic method has been studied. The TCB was characterized by Fourier transform Infrared (FTIR) Spectral studies and Scanning Electron Microscope (SEM), Energy Dispersive Analysis of X-ray (EDAX). The photocatalytic activity of TCB for the decolorization of the three dyes is much higher than that of bare titanium dioxide, which can be attributed to the synergistic effect of TiO2 and chitosan. The chitosan adsorbs dye molecule which continuously supplies, dye molecule for degradation by TiO2 thereby preventing the electron-hole recombination. The photocatalytic experiment was carried out by varying different parameters such as irradiation time, dosage, pH, substrate concentration and co-ions. The kinetics of decolorization of dyes are explained on the basis of Langmuir-Hinshelwood mechanism. The mineralization of dyes has also been confirmed by COD measurements. (C) 2014 Published by Elsevier B.V.