Photo-reduction of Hexavalent Chromium in Aqueous Solution in the Presence of TiO2 as Semiconductor Catalyst

The objective of this work is to determine the optimal conditions for the reduction of the hexavalent chromium in water using the photocatalytic system TiO2/UV. The results show that the effectiveness of this system was significantly higher compared to direct photolysis. The influence of parameters such as photocatalyst loading and initial concentration of the substrate was studied. The study of the influence of pH shows that the reduction rates are grater for acid solutions. Furthermore the experimental results show that the presence of H2O2 at small concentration (10-6M) accelerates the reduction. However at higher concentration (10-4M) H2O2 inhibits the reduction. The presence of inorganic ions such as Cl- and SO42-does not seem to have any significant influence on the reduction rate of Cr (VI).