Photocatalytic degradation of organic dyes in the presence of nanostructured titanium dioxide

Titanium dioxide photocatalyst was synthesized through a low temperature co-precipitation process
using TiCl4 as a precursor for degradation of Rhodamine B (RB) Acid Red 57 (AR57) and under UV
irradiation. The activities of the photocatalyst prepared at calcination temperature 400, 500 and 600 C
were investigated. The resultant TiO2 photocatalyst was characterized by different techniques, such as
XRD, SEM, EDX, N2 adsorption and titration for the determination of the zero point charge (pHZPC). It has
been found that 400 C annealed sample of TiO2 exhibits the highest photocatalytic dye degradation
efficiency of 93.8 and 90.7% for RB and AR57, respectively within 190 min. The effect of operation pa-
rameters such as pH, catalyst dosage, initial dye concentration, as well as the influence of calcination
temperatures was evaluated. Results showed that the degradation rate of dyes increased with the
increased dosage of TiO2 catalyst and decreased initial concentration of the dye. Furthermore, the ki-
netics and scavengers of the reactive species during the degradation were also studied. It was found that
the degradation of RB and AR57 fitted the first-order kinetics and OH radicals were the main species.
Formation of OH free radicals during irradiation is determined by photoluminescence studies using
terephthalic acid as probe molecule.