Descoloração do azul de metileno por meio de fotocatálise heterogênea utilizando radiação solar

Abstract

The production of industrial effluents is a frequent problem in society taking into account the environmental impact they can cause. In this context, the textile industry stands out due to the fact that it requires large amounts of water in their chemical discharges, therefore generating proportionally high quantities of wastewater, their drainage has the characteristic of containing high concentrations of dyestuff used in the stages of dyeing. Today the management performed by the industry are basically physico-chemical followed by biological treatment. There is a need to implement cheap and efficient treatment for this industry field, in this scenario the AOPs and especially the photocatalysis may qualify as an adequate approach. The catalysed photolysis is performed through the use of a photocatalyst, which can be suspended or immobilized while being activated by radiation. Therefore, this work has the objective of experimenting on the discoloration of methylene blue, a dye used extensively in the textile industry, through heterogeneous solar photocatalysis using niobium pentoxide as catalyst, optimizing parameters such as pH, catalyst concentration and calcination temperature of Nb2O5. The tests were carried out in a batch reactor with air pumping and mechanical agitation, the parameters were determined by the experimental design and the aliquots were removed at regular intervals in order to observe its discoloration. The results indicate that the calcination of the catalyser affects its structure and the band gap, in addition to that, it is also noticeable that the pH of 5.5 is the optimum point for the discoloration, contrary to the increase in catalyst concentration, which has no positive influence on the reaction. Thus, it is possible to affirm that the photocatalysis using niobium pentoxide in suspension while being activated by solar radiation is efficient for the degradation of methylene blue.