Examinando por Materia "Photocatalysis"

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    Dielectric relaxation studies in activated carbon doped Titanium Dioxide at high temperatures
    (Universidad del Valle, 2017-01-30) Castañeda, Karen A.; Cuellar, Ingrith P.; Castillo, José H.
    (Eng) Titanium Dioxide (TiO2) has been an object of different investigations in the recent years, principally to its applications in solar cells due to its interesting optic, electric and magnetic properties. In this work is presented the dielectric response study of activated carbon doped TiO2 in pressed pills in different Molar relations. The electric behavior of the composites is obtained by bringing the samples to a Nitrogen and Helium atmosphere and studying with complex impedance spectroscopy, in the 50Hz to 5 MHz frequency interval and from room temperature to 723 K. The experimental results showed that the Nitrogen atmosphere leads to an anionic doping, in which an nitrogen anion (A) gets into the TiO2 lattice, replacing an oxygen and forming TiO2-x Ax.
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    Microbiology cell-staining wastewater treatment using T iO 2 thin films
    (Universidad del Valle, 2015-06-19) Fernández, Jorge A.; Cardozo, Magda G.; Carrascal, Ana K.; Salcedo, Juan C.; Pedroza, Aura M.; Daza, Carlos E.
    (Eng) Microbiology cell-staining wastewater was treated by UV/TiO 2 thin films photocatalysis. A simple method of applying gravity sedimentation over grass-type substrate was used for the preparation of the films. The use of Na4 P2 O7, microwaves, and ultrasounds were studied for decreasing the TiO2 grain sizes on the films. It was established that the best method for reducing grain size resulted from a combination of Na4P2O7 (0.01M) and microwave radiation (700 W, 20 min). The Films were characterized by several microscopic and spectroscopic methods. Anatase phase (gap energy of 3.2 eV) and grain sizes averaging 83 nm were achieved. Photocatalysis tests using TiO2-film showed 99.5 % of decolorization, 79 % TOC abatement, and total microbial inactivation after 14 h of treatment. No bacteria re–growth was found 48 h after the treatment was completed.