Resumo

TOBON, Jorge I.; COHEN, Juan D.  e  DORKIS, Ludovic. Photocatalytic activity under visible light irradiation of cement based materials containing TiO _2-x N _y nanoparticles. Rev.fac.ing.univ. Antioquia [online]. 2020, n.94, pp.87-96. ISSN 0120-6230.  https://doi.org/10.17533/udea.redin.20190730.

Self-cleaning activity of Portland cement pastes blended with nanoparticles of titanium oxynitride (TiO2− x N y ) was studied. Samples with various amounts of TiO2− x N y (1% and 3%) were evaluated under irradiation of UV and visible light, and with two curing ages (65 hour and 28 days). Rhodamine B was the pigment used and its loss of color on the cement pastes was carried out using a Spectrometer UV/Vis measuring the coordinates CIE (Commission Internationale de l’Eclairage) L*, a*, b*. Discoloration of Rhodamine B on the surface of the samples was established as the photocatalytic efficiency coefficient (ε). In addition, samples with TiO2 nanoparticles (1% and 3%) were studied under the same conditions and their performances were compared with TiO2-xNy. The presence of nitrogen in the tetragonal structure of TiO2 was evidenced by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectrophotometry and Carbon, Hydrogen and Nitrogen (CHN) analysis. The band gap for TiO2 and TiO2-xNy was determined by the transformed Kubelka-Munk function ([F(R∞) hv]1/2). The results have shown a similar behavior for both additions under UV light irradiation, with 3% being the addition with the highest photocatalytic efficiency obtained in the early ages of curing time. TiO2− x N y showed activity under irradiation with visible light, unlike TiO2, which could only be activated under UV light. At the late curing ages, the samples with 3% of TiO2-xNy showed the highest efficiency under irradiation of UV and visible light.

Palavras-chave : Self-cleaning cement; nanoparticles of titanium oxynitride (TiO_{2- x} N _y ); photocatalitic activity under visible light; rhodamine B abatement; photocatalysis.

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