Methylene blue photodegradation by sensitized TiO2 thin films with pigments isolated from cyanobacterial biomass
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Universidad Santo Tomás. Seccional Bucaramanga
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Las industrias textiles generan en sus procesos una diversidad de contaminantes, entre los que se encuentran los colorantes, la mayoría recalcitrantes no biodegradables y de difícil tratamiento por los métodos convencionales, por lo que se hace necesario implementar tecnologías alternativas de tratamiento para su degradación. La fotocatálisis heterogénea permite usar semiconductores como el dióxido de titanio (TiO2) para la oxidación de una gran cantidad de contaminantes de difícil tratamiento por los métodos convencionales. Una limitante importante para la utilización de semiconductores de TiO2 es el requisito de la luz UV, sin embargo, esta dificultad puede ser superada al sensibilizar el semiconductor con sustancias de origen sintético o natural para extender su actividad en la región visible. En este trabajo se evaluó el efecto de pigmentos separados (Clorofila a y ficocianina C) obtenidos de biomasa de cianobacterias aisladas de la Ciénaga de Malambo del municipio de Malambo del Departamento del Atlántico-Colombia sobre las propiedades fotocatalíticas del dióxido de titanio. Se sensibilizaron películas de TiO2 con cada uno de los extractos separados y la energía del band gap fue determinada por espectroscopia de reflectancia difusa. Finalmente se realizó el montaje de los ensayos a escala laboratorio para evaluar la degradación fotocatalítica del colorante azul de metileno. La clorofila a y la ficocianina C fueron identificados como sensibilizadores presentes en el extracto metanólico de la biomasa cianobacteriana. Adicionalmente, las películas de TiO2/Clorofila a presentaron un mayor porcentaje de fotodegradación en comparación de las películas de TiO2/Ficocianina C. Finalmente, los resultados obtenidos permitieron verificar que los colorantes naturales obtenidos del extracto de la biomasa, pueden ser utilizados para mejorar la respuesta foto catalítica del TiO2 bajo irradiación visible.
The textile industries generate a great diversity of pollutant waste, among these; dyes most of them non-biodegradable and recalcitrant are hard to treat by conventional methods, so it is necessary to implement alternative treatment technologies for their degradation. Through heterogeneous photocatalysis, a semiconductor such as titanium dioxide (TiO2) can oxidate different organic compounds that are difficult to treat by conventional methods. A critical drawback of using TiO2 semiconductors is the requirement of UV light; however, the semiconductor sensitization with chemical substances from synthetic or natural origin to extend its activity in the visible region is a typical alternative to solve this issue. This work evaluated the effect of separate pigments (Chlorophyll a and phycocyanin C) obtained from cyanobacteria biomass isolated from the Malambo Swamp in the Department of Atlántico-Colombia on the photocatalytic properties of titanium dioxide. TiO2 films were sensitized with each of the extracts and the band gap energy was obtaining by diffuse reflectance spectroscopy. Finally, the laboratory-scale tests were carried out to evaluate the photocatalytic degradation of the methylene blue dye. Chlorophyll and phycocyanin were identified as sensitizers present in the methanolic extract of cyanobacterial biomass. Additionally, TiO2/Chlorophyll films had a higher percentage of photodegradation than the TiO2/Phycocyanin films. Finally, the results showed the natural dyes obtained from the biomass extract are suitable to improve the photocatalytic response of TiO2 under visible irradiation.
The textile industries generate a great diversity of pollutant waste, among these; dyes most of them non-biodegradable and recalcitrant are hard to treat by conventional methods, so it is necessary to implement alternative treatment technologies for their degradation. Through heterogeneous photocatalysis, a semiconductor such as titanium dioxide (TiO2) can oxidate different organic compounds that are difficult to treat by conventional methods. A critical drawback of using TiO2 semiconductors is the requirement of UV light; however, the semiconductor sensitization with chemical substances from synthetic or natural origin to extend its activity in the visible region is a typical alternative to solve this issue. This work evaluated the effect of separate pigments (Chlorophyll a and phycocyanin C) obtained from cyanobacteria biomass isolated from the Malambo Swamp in the Department of Atlántico-Colombia on the photocatalytic properties of titanium dioxide. TiO2 films were sensitized with each of the extracts and the band gap energy was obtaining by diffuse reflectance spectroscopy. Finally, the laboratory-scale tests were carried out to evaluate the photocatalytic degradation of the methylene blue dye. Chlorophyll and phycocyanin were identified as sensitizers present in the methanolic extract of cyanobacterial biomass. Additionally, TiO2/Chlorophyll films had a higher percentage of photodegradation than the TiO2/Phycocyanin films. Finally, the results showed the natural dyes obtained from the biomass extract are suitable to improve the photocatalytic response of TiO2 under visible irradiation.
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Methylene blue, Heterogeneous photocatalysis, Sensitization, Titanium dioxide, Azul de metileno, Fotocatálisis heterogénea, Sensibilización, Dióxido de titanio
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