Improving of photocatalytic activity of barium ferrate via bismuth and copper co-doping for degradation of paracetamol under visible light irradiation.

Nanosized Ba1-xBixFe1-xCuxO3 (12-50 nm) with x values of 0, 0.01, 0.05, and 0.1 system was prepared using the Pechini method. Structural, morphological, surface and optical characterizations were performed for the prepared samples. Cubic phase was the predominant phase for the undoped BaFeO3 and Bi and Cu co-doped BaFeO3 samples. Minor phases of monoclinic Ba2Fe2O5, orthorhombic BaFe2O4 and orthorhombic BaCO3 were identified for all the prepared samples. Ba0.95Bi0.05Fe0.95Cu0.05O3 sample has the lowest band gap (2.43 eV). 98.1% paracetamol removal was achieved with 0.75 g/L of Ba0.95Bi0.05Fe0.95Cu0.05O3 at pH 9 after 120 min. The paracetamol degradation follows the pseudo first-order kinetics. HO• is the main oxidative species responsible for the paracetamol degradation. Gas chromatography-mass spectrometry (GC-MS) analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba0.95Bi0.05Fe0.95Cu0.05O3 to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible (UV/Vis) spectroscopy study at different reaction times.

Visible light activity of BaFe1-xCuxO3-δ as photocatalyst for atrazine degradation.

Nanosized BaFe1-xCuxO3 powders were prepared using the Pechini method. To limit grain growth and agglomeration, the temperature of calcination was limited to 800 °C. For all samples, the cubic form of BaFeO2.75 was predominant with minor additional phases. Cu doping was found to have a remarkable effect on the structural cubic unit cell parameter as the Cu concentration increased. As shown by XRD,the samples were in the nanometer size range (17-63 nm). However, as the Cu concentration increases, the agglomeration increases with the highest surface area for the BaFe0.95Cu0.05O3 composition, which also displays the highest photocatalytic atrazine degradation. For this sample, more than 90% degradation of atrazine was obtained at the optimum conditions (120 min irradiation under visible light at pH 11 using 0.75 mg of the catalyst). The Atrazine degradation was found to follow the pseudo-order kinetics. GC/MS was used to detect the intermediates and the reaction pathways. All the prepared samples and produced waters at the end of the experiment were found to be nontoxic.

Elucidating the genesis of Bi2MoO6 catalyst by combination of synchrotron radiation experiments and Raman scattering.

Combination of in situ Raman scattering with high-resolution XRD and XAS techniques has proven to be a powerful tool to elucidate the crystal growth of gamma-Bi2MoO6 under hydrothermal conditions.