Bulk phase degradation of Acid Red 14 by nanophotocatalysis using immobilized titanium(IV) oxide nanoparticles

Immobilized titanium(IV) oxide nanoparticles were used for the photocatalytic degradation of Acid Red 14 (AR 14). A simple and effective method was used for immobilization of titanium(IV) oxide nanoparticles. Photocatalytic degradation processes were performed using pilot scale (7 L) colored dye solutions. UV–vis and ion chromatography (IC) analyses were employed to obtain the details of the photocatalytic degradation of AR 14. It has been found that adsorption has a negligible effect on the aqueous dye concentration and the photocatalytic process occurred at solution bulk. The effects of operational parameters such as H2O2, dye concentration, anions (NO3−, Cl−, SO42−, HCO3− and CO32−) and pH were investigated. Reaction rate was drastically inhibited by carbonate. Produced aromatic intermediates were not studied. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediates where, they were further oxidized slowly to CO2. Nitrate and sulfate anions were detected as the photocatalytic mineralization of AR 14. Kinetics analysis indicates that the photocatalytic decolorization rates can usually be approximated first-order model for AR 14. Results show that the employment of optimal operational parameters may lead to complete decolorization and mineralization of dye solutions.