Solar-light-driven LaFe x Ni1- x O3 perovskite oxides for photocatalytic Fenton-like reaction to degrade organic pollutants

Abstract

LaFe _x Ni_{1- x} O₃ perovskite oxides were prepared by the sol-gel method under various conditions, including different pH values (pH 0 and pH 7) and different calcination temperatures (500-800 °C) as well as different Fe/Ni ratios (1/9, 3/7, 5/5, 7/3, 9/1). The samples were examined by XRD, DRS, BET, and SEM to reveal their crystallinity, light-absorption ability, specific surface area, and surface features, respectively. The photocatalytic Fenton reaction was conducted using various LaFe _x Ni_{1- x} O₃ perovskite oxides to decompose the methylene blue molecules. Accordingly, the synthesis condition of pH 0, calcination temperature at 700 °C, and Fe/Ni ratio = 7/3 could form LaFe_0.7Ni_0.3O₃ perovskite oxides as highly efficient photocatalysts. Moreover, various conditions during the photocatalytic degradation were verified, such as pH value, catalyst dosage, and the additional amount of H₂O₂. LaFe_0.7Ni_0.3O₃ perovskite oxides could operate efficiently under pH 3.5, catalyst dosage of 50 mg/150 mL, and H₂O₂ concentration of 133 ppm to decompose the MB dye in the 1st order kinetic rate constant of 0.0506 s^-1.

Keywords: LaFeO3; LaNiO3; methylene blue (MB); perovskite oxides; photocatalyst.

Figure 1

The characteristic XRD patterns of LaNiO₃ at different calcination temperatures.

Figure 2

The characteristic XRD patterns of LaFeO₃ at different calcination temperatures.

Figure 3

The characteristic XRD patterns of LaFe_xNi_1−xO₃.

Figure 4

The crystal diameters of samples with various Fe/Ni doping ratios.

Figure 5

(a) The DRS spectrum and (b) the pictures of samples with various Fe/Ni doping ratios.

Figure 6

Specific surface area, pore size, and pore volume of the samples with different Fe/Ni ratios.

Figure 7

The FESEM images of LaFe_xNi_1−xO₃ prepared at pH 0 (at the magnification of 100,000×).

Figure 8

MB degradation experiments using various LaFe_xNi_1−xO₃ with different Fe/Ni ratios prepared at (a) pH 0; (b) pH 7.

Figure 9

Kinetic analysis of MB degradation experiments using various LaFe_xNi_1−xO₃ with different Fe/Ni ratios at (a) pH 0 and (b) pH 7.

Figure 10

(a) The C/C₀ and (b) 1st order kinetic analysis of the MB photodegradation using LaFe_0.7Ni_0.3O₃ operating at different pH values.

Figure 11

(a) The C/C₀ and (b) 1st order kinetic analysis of the MB photodegradation using LaFe_0.7Ni_0.3O₃ operating at different catalyst dosages.

Figure 12

(a) The C/C₀ and (b) 1st order kinetic analysis of the photodegradation using LaFe_0.7Ni_0.3O₃ operating at different H₂O₂ addition.