Catalytic photodegradation of Congo red in aqueous solution by Ln(OH)3 (Ln = Nd, Sm, Eu, Gd, Tb, and Dy) nanorods

The stable and crystalline phase pure Ln(OH)3 (Ln = Nd, Sm, Eu, Gd, Tb, and Dy) nanorods were synthesized by a facile hydrothermal method starting with corresponding rare-earth chloride hexahydrate LnCl3·6H2O, ammonia NH3·H2O and cationic surfactantcetyltrimethylammonium bromide (CTAB). X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used as the structural probes in order to check the phase purity, and to examine the morphologies and microstructures of the synthesized compounds. The structural analysis reveals that the obtained compounds are rare-earth hydroxides with one-dimensional (1D) rod-like nanostructures. The formation mechanism of the Ln(OH)3 nanorods was also proposed. The photoactivity of Ln(OH)3 (Ln = Nd, Sm, Eu, Gd, Tb, and Dy) nanorods was tested by measuring the degradation of azo dye Congo red (CR). The results show an excellent removal capacity for organic pollutants CR from wastewater, making them promising candidates for the wastewater treatment.

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► Ln(OH)3 nanorods are fabricated by a facile hydrothermal method.
► The Ln(OH)3 nanorods are crystalline with hexagonal crystal structure.
► The Ln(OH)3 nanorods exhibit outstanding catalyzed degradation performance for Congo red.