BWO and Lu-BWO were synthesized by coprecipitation method. Lu-BWO sample exhibits the highest visible-light-responsive photocatalytic performance for the degradation of MB. h⁺ and ˙O₂⁻ are the main active species in the photocatalytic degradation.

The carbonatation of La₂O₃oxide and the decarbonatation of lanthanum carbonate phase La₂O₂CO₃are investigated using thermal and thermogravimetry analyses under CO₂gas flow. The initial phase La₂O₃is first elaborated from pyrolysis of a LaOHCO₃precursor. Then, thermal and thermogravimetry analyses are carried out under CO₂flow, as temperature increases then decreases. The carbonatation kinetics of La₂O₃is determined at three fixed temperatures. Electrical impedance spectroscopy is performed to determine the electrical responses associated with ionic mobilities and phase changes, in the temperature range 25 to900∘C. The electrical conduction during heating underCO2gas flow should be linked to two regimes of ionic conduction of the carbonate ions. From these electrical measurements, the ionic mobility of carbonate ionsCO3 2−is found to be close to 0.003 ⋅10−4 cm2 s−1 V−1at750∘C for the monoclinic La₂O₂CO₃phase.

In this study, we prepared spheroid microstructures of monoclinic bismuth phosphate BiPO₄ by a facile solid-state reaction at 500 °C. The crystal structure was refined using the Rietveld method, where the crystal cell was resolved using a monoclinic system (parameters a, b, c, β) with space group P2₁/n. SEM images showed that the solid catalyst presented homogeneous morphologies. These BiPO₄ microparticles (BiP-500) have been used as photocatalysts to photodegrade, under UV light irradiation, three cationic dyes (Rhodamine B, RhB; Methylene Blue, MB; and Toluidine Blue, TB), three anionic dyes (Congo Red, CR; Orange G, OG; and Methyl Orange, MO) and mixtures of RhB-MB, RhB-OG and MO-OG organic dyes. The photodegradation efficiency of these BiP-500 microparticles is found to be optimal in the case of RhB solutions, RhB-MB and RhB-OG binary mixtures. The BiP-500 catalyst shows a high selectivity for the conversion of the mixture of dyes into CO₂ and H₂O. Total organic carbon analysis of an anionic dye and a cationic dye (RhB, OG and RhB-MB) confirms the mineralization of the pollutants in the presence of BiP-500 particles. The photocatalytic efficiency of our BiP-500 photocatalyst has been confirmed, with a view to facilitate applications in the field of the depollution of wastewater in the agricultural environment by the degradation of parathion-methyl (PM) as a pollutant.