Enhanced photocatalytic activity of Ni-doped BiFeO3 nanoparticles for degradation of bromophenol blue in aqueous solutions

In the study, BiFe1-xNixO3 (x = 0, 0.01, 0.03, and 0.05) nanoparticles as catalysts were prepared using a sol-gel procedure to degrade bromophenol blue (BPB) as a dye. The prepared catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. The optical band gap of samples was calculated from the reflectance spectra in the UV-Vis region using the Kubelka-Munk equation. The effects of several experimental parameters on the photocatalytic degradation of BPB, such as type of light irradiation, amount of hydrogen peroxide (H2O2), BiFeO3 (BFO) dosage, initial pH of the dye and nickel doping percentages, were evaluated and optimized. The optimal conditions were obtained in the presence of a concentration of 20 mg L-1 of BPB, 0.50 mL H2O2, 0.10 g of the catalyst and ultraviolet light at pH 2. Also, an improvement in the photocatalytic activity of Ni-doped BFO nanoparticles was observed for BPB under optimal conditions. The duration of the BPB degradation process with Ni-doped BFO nanoparticles was reduced by almost half compared to un-doped BFO under optimal conditions, and the rate constant (k) of pseudo-first-order per unit (min(-1)) increased from 0.0144 with the pure BFO to 0.0325, 0.0275 and 0.0344 via the Ni-doped BFO with different percentages of Ni 1%, 3% and 5%y. This research presents an effective photocatalytic method for the BPB degradation process with high efficiencies of 49.05, 79.74, 84.06 and 82.58% by un-doped BFO and Ni-doped BFO with different values of Ni 0.01, 0.03, and 0.05 in 120 min. [GRAPHICS]