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: 3.41). 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Titania (TiO2) photocatalysts were prepared by aqueous hydrolysis of TiCl4 and deposition with NaOH at 400-900°C. The powders obtained have been characterized using X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The photocatalytic activities of the samples were also examined using the degradation of beta-naphthol as a model reaction. As the calcination temperature increases, the anatase and rutile crystallite sizes increase. TiO2 powder calcined at 700°C exhibits much higher photocatalytic activity than commercial TiO2 Degussa P-25. The photodegradation rate of beta-naphthol using TiO2 700°C particles was faster than that using TiO2 Degussa P-25 as photocatalyst by 2 times. Conversely, prolonged calcination at higher temperatures (900°C) is detrimental to photoactivity.
    Journal of Applied Sciences. 01/2006; 6(7):1553-1559.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Terephthalic acid (TPA) wastewater is traditionally being treated by biological method. This study investigates the degradation of three major toxic target organic species, namely terephthalic acid (TPA), isophthalic acid (IPA), benzoic acid (BA), present in the TPA wastewater, by several advanced oxidation processes. The performance of three main oxidation processes such as photofenton oxidation (UV-H(2)O(2)-Fe), photocatalytic ozonation (UV-O(3)-Fe) and photofenton ozonation (UV-O(3)-H(2)O(2)-Fe) were studied. Studies were conducted with and without dilution of TPA wastewater. Photofenton ozonation was found to be most efficient by achieving almost complete destruction of all the three target organics in less than 30 minutes of reaction. In combining several oxidation processes, a comparative study was also carried out between one step addition of oxidants and stepwise addition.
    Journal of Environmental Science and Health Part A 02/2006; 41(8):1685-97. · 1.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, treatment of phthalates by electrocoagulation employing stainless steel electrodes was investigated using dimethyl phthalate (DMP) as a model compound. DMP was completely destructed within 30 min up to the high initial concentration of 100mg/L while total mineralization was also obtained within a couple of hours. The applied current density of 22.5 mA/cm(2) and electrolyte (NaCl) concentrations varying between 1000 and 1500 mg/L as chloride resulted in the highest treatment performance. The initial solution pH (2-6) had practically no effect on the process efficiency. Desorption experiments and the reaction rates obtained for DMP, COD and TOC abatements appeared to be a strong evidence of an oxidative removal mechanism. DMP removal fitted first order kinetics. COD and TOC removals began after the total DMP removal and also fitted first order kinetics. Activated sludge inhibition experiments revealed that toxicity could be significantly reduced by electrocoagulation application.
    Journal of hazardous materials 07/2009; 171(1-3):932-40. · 4.14 Impact Factor


Available from