Catalisadores formados por óxidos de ferro e grafeno aplicados na descoloração do corante índigo carmim

Abstract

The textile industry is a sector that is present in our daily lives. However, it is recognised for its polluting potential. Indigo carmine (IC) is one of the most widely used dyes, but it is highly toxic, especially when disposed of in reuse water. Advanced oxidative processes using photocatalysts are ways of eliminating this compound. Materials such as Fe3O4/RGO are promising due to their versatility in catalysis applications. In this work, two catalysts (Fe55 and Fe73) with different iron oxide contents (55% and 73%) were synthesised for application in photo-Fenton reactions to decolourise IC. The formation of Fe3O4 and γ-Fe2O3 was identified in both catalysts, with significant ferromagnetic behaviour. Their photocatalytic performance was assessed in the IC solution decolourisation reactions. In the photolysis test with H2O2, the solution was completely discoloured at the end of the process, while without, the values were practically zero. In the adsorption tests, equilibrium was reached after 30 min with the catalysts reaching 15%. In the Photo-Fenton tests, total decolourisation was achieved in 60 min. The Fe55 and Fe73 catalysts achieved 71.8% and 44% mineralisation of the dye respectively at the end of the reaction. Thus, Fe55 is better at completely decolourising the IC and mineralising it more efficiently.