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Various standards have been published in an effort to rationalize and unify the evaluation and quantification of photocatalytic activity. The experimental conditions stated in the published standards and test methods differ in many aspects that make it very difficult to compare different results. This paper focuses on the influence of the different parameters involved in the photocatalytic process. The photocatalytic active material consists of white mortar, surface coated by TiO

This paper analyzes the effect of some properties of different catalysts on the photocatalytic activity. The efficiency has been determined for two different processes: NOx abatement and self-cleaning for Rhodamine B and tobacco extract being, the TiO 2 based photocatalyst, supported as coatings on white mortar. Eight different catalysts were tested, seven commercial ones and one home-made catalyst with improved visible light absorption properties. Additionally, some of them were submitted to exposition to water and/or calcinations to alter their physical properties. A kinetic approach was used to evaluate the photocatalytic activity, being the first reaction constant (for NO) and just empirical constants (for self-cleaning) the parameters used for the comparison of the different materials. As a result, the efficiency, even for ranking, is dependent on the type of contaminant used in the experiment. In general, NO oxidation and tobacco followed similar trends while no clear relations were found for Rhodamine B. RESUMEN: Fotocatálisis heterogénea en materiales de construcción: efecto de las propiedades de los catalizadores en la eficiencia de degradación de NOx y autolimpieza.En este trabajo se analiza el efecto de las propiedades de distintos catalizadores en la actividad fotocatalítica de degradación de NOx y autolimpieza, para Rodamina B y extracto de tabaco. Se han ensayado ocho fotocatalizadores, basados en TiO 2 y soportados sobre mortero blanco; siete de ellos comerciales y uno sintetizado en el laboratorio con absorción mejorada en el visible. Adicionalmente, las propiedades físicas de algunos de ellos se alteraron mediante tratamientos con agua y/o por calcinación. La actividad fotocatalítica se ha evaluado mediante aproximación cinética, siendo la constante de reacción de primer orden (para NO) y constantes empíricas de ajuste (para autolimpieza) los parámetros de comparación entre materiales. Como resultado, la eficiencia depende del contaminante utilizado en el experimento de evaluación. En general, en este estudio, oxidación de NO y de extracto de tabaco presentan tendencias similares mientras para Rodamina B no se encontró correlación clara ninguna.

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Co-doped visible light active photocatalysts were obtained by chemical modification of TiO