Cu/NbO, Fe/NbO and Cu-Fe/NbO applied in salicylic acid degradation: Parameters studies and photocatalytic activity.

This study describes the synthesis of Cu/NbO, Fe/NbO, and Cu-Fe/NbO catalysts obtained by incorporating copper and/or iron metals into niobium pentoxide (NbO). The new materials were characterized by the following techniques: Thermogravimetric Analysis (TA), surface and pore analysis, X-ray diffractometry (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The catalyst was applied in the photocatalytic degradation of salicylic acid (SA). The influence of different parameters (calcined temperature, pH, and metal addition) on the photocatalytic reaction was evaluated. The results indicated that catalysts containing copper were more active and pH influenced the SA degradation process. SA removal results indicated that Cu/NbO photocatalyst presented a 1.5 fold higher degradation after 120 min in comparison to Cu-Fe/NbO and 4.6 fold higher than Fe/NbO catalyst, all them calcined at 400 °C. In tests carried out in the presence of formic acid, increasing the pH from about 3 to 7 allowed an almost 3.4-fold increase in SA degradation for the Cu-Fe/NbO catalyst calcined at 400 °C.