Synthesis, characterization and photocatalytic properties of lanthanum oxy-carbonate, lanthanum oxide and lanthanum hydroxide nanoparticles

• Nanoparticles of La2O3, La2O2CO3 and La(OH)3 were prepared via thermal decomposition route.
• La2O2CO3 shows a promising photocatalytic activity for degradation of methyl orange.
• Lanthanum oxy-carbonate nanocatalyst is stable and reusable under ultraviolet irradiation.

A simple thermal decomposition route has been developed to prepare La2O3 and La2O2CO3 nanoparticles. Sonication of La2O3 nanoparticles in water at room temperature is accompanied to the formation of La(OH)3 nanoparticles. The effect of addition of citric acid, as disperser, was also investigated on the phase formation and particle size distribution of the products. It is observed that citric acid has no effect on the particle size of the samples. The prepared nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses. Photocatalytic activity of the products was examined for degradation of methyl orange, a common reactive dye, as a pollutant under ultraviolet irradiation in the wastewater. The results show that La2O2CO3 nanoparticles are promising materials in this photocatalytic degradation with no significant loss of activity even after four cycles of successive uses. A pseudo-first-order kinetic is obtained for the photocatalytic degradation of methyl orange over La2O2CO3 nanoparticles according to the Langmuir–Hinshelwood analysis.

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