Photocatalytic degradation of phthalic acid on TiO2 nanoparticles

Department of Chemistry, National Research Council of Argentina, University of Mar del Plata, P.O. Box 422, 7600 Mar del Plata, Argentina
Applied Catalysis A General (Impact Factor: 3.94). 06/2001; 208:419-426. DOI: 10.1016/S0926-860X(00)00727-4

ABSTRACT The photocatalytic oxidation of phthalic acid was studied in aerated sols of TiO2 nanoparticles under monochromatic irradiation at pH=4.25. We report initial quantum efficiencies for phthalate degradation, ΦPHT0, as a function of phthalate concentration and quantitative yields of the primary products. Formation rates of the hydroxyl radical adduct (DMPO-OH) from the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) were determined at various initial concentrations of phthalate. Kinetic analysis of the spin-trapping experiments indicates that phthalate is oxidized by a dual hole-radical mechanism. The effect of added phosphate on phthalate photocatalytic degradation is examined in detail. Dark-adsorption of phthalate on TiO2 particles is significantly inhibited by the presence of phosphate, however, ΦPHT0 is almost independent of phosphate concentration.

1 Follower
41 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: TiO2 pillared montmorillonites were prepared by introducing Ti4+ into a layer of montmorillonite modified with or without cetyltrimethylammonium bromide. The components and texture of the prepared composites were characterized by thermogravimetric analysis, X-ray powder diffraction and scanning electron misroscopy. The adsorption and photocatalytic degradation performance of a model environmental endocrine disruptor, dimethyl phthalate ester, were investigated using this newly prepared hydrophobic TiO2 pillared montmorillonite photocatalyst. The adsorption of dimethyl phthalate ester from water varied from 9% to 28% on the prepared hydrophobic photocatalyst. Although the experimental results showed that the photocatalytic activity of the hydrophobic photocatalyst was slightly lower than that of hydrophilic one, electron spin resonance verified that hydroxyl radicals were also generated in hydrophobic TiO2 pillared montmorillonite photocatalyst under UV irradiation. To elucidate the decomposition mechanism of dimethyl phthalate ester, 12 main photocatalytic intermediates were identified during the photocatalytic degradation process, and a plausible degradation mechanism was also proposed.
    Research on Chemical Intermediates 01/2008; 34(1):67-83. DOI:10.1007/BF03039136 · 1.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chromium-, manganese- and cobalt-doped titanium dioxide photocatalysts containing 0.2, 0.5 or 1 at.% of metal-dopant were investigated by UV–VIS, FT-IR, near-IR and electron paramagnetic resonance (EPR) spectroscopic techniques. The presence of the doping ions in the titania structure caused significant absorption shift to the visible region compared to pure TiO2 powder (P25 Degussa). The EPR spectra of TiO2 powders containing chromium showed the superposition of three types of individual paramagnetic species (β-, γ- and δ-signals), whose relative EPR intensity is significantly dependent on the dopant concentration, as well as on the photocatalysts preparation and treatment. The EPR spectra of the chromium-doped photocatalysts heated in H2/N2 atmosphere corresponded to the Cr(III) ions occupying vacated cation sites in the rutile or anatase crystal lattice. The characteristic feature of the EPR spectra of the Mn/TiO2 samples is a sharp six-line Mn(II) component centered on geff=1.99, flanked by shoulders with a weak feature, which appeared on geff=2.66 and 4.32. The photocatalytic activity of the various metal-doped TiO2 samples was tested in aqueous or dimethylsulfoxide (DMSO) suspensions using EPR spin trapping technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trap. The ability of the irradiated photocatalysts to generate reactive oxygen species, namely hydroxyl radicals and super-oxide anion radicals, which were trapped as the corresponding DMPO-adducts was investigated.
    Applied Catalysis B Environmental 04/2002; 37(2-37):91-105. DOI:10.1016/S0926-3373(01)00335-6 · 7.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new adsorption measurement method based on photoelectrochemical oxidation principles has been developed. The method can be used to directly quantify the amount of adsorbates at a TiO2 electrode surface in a sensitive and accurate manner. The adsorption of phthalic acid was studied as a test case. The relationship between the amount of adsorbate at the TiO2 surface and the concentration of phthalic acid in the solution was obtained. The adsorption of phthalic acid on TiO2 surface was shown to follow a Langmuir type adsorption model. For the first time, the adsorption equilibrium constant of an adsorbate at TiO2 surface has been photoelectrochemically measured. The adsorption equilibrium constant of phthalate on TiO2 porous film at pH 4.0, K=4.0×104 M−1, was obtained using our method, which was close to that obtained by conventional methods. The effect of solution pH on the amount of adsorbate at TiO2 surface was also investigated. The results indicate the adsorption of phthalic acid is mainly of chemical bonding nature.
    Journal of Photochemistry and Photobiology A Chemistry 03/2003; 156(1-3). DOI:10.1016/S1010-6030(02)00409-4 · 2.50 Impact Factor
Show more


41 Reads
Available from