Methylene blue photodegradation by sensitized TiO2 thin films with pigments isolated from cyanobacterial biomass
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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