Photocatalytic degradation of phthalic acid on TiO2 nanoparticles

The photocatalytic oxidation of phthalic acid was studied in aerated sols o f TiO2 nanoparticles under monochromatic irradiation at pH = 4.25. We repor t initial quantum efficiencies ibr phthalate degradation. phi (0)(PHT), as a function of phthalate concentration and quantitative yields of the primar y products, Formation rates of the hydroxyl radical adduct (DMPO-OH) from t he spin trap 5.5-dimethyl-l-pyrroline-N-oxide (DMPO) were determined at var ious initial concentrations of phthalate. Kinetic analysis of the spin-trap ping experiments indicates that phthalate is oxidized by a dual hole-radica l mechanism. The effect of added phosphate on phthalate photocatalytic degr adation is examined in detail. Dark-adsorption of phthalate on TiO2 particl es is significantly inhibited by the presence of phosphate, however, phi (0 )(PHT) is almost independent of phosphate concentration. (C) 2001 Elsevier Science B.V. All rights reserved.