Synthesis of barium oxide nanoparticles and its novel application as a catalyst for the photodegradation of malachite green dye

The synthesis of undoped barium oxide (BaO) and neodymium (Nd)-doped BaO nanoparticles (NPs) was carried out through the co-precipitation technique. The synthesis of cubic structure BaO NPs was confirmed through X-ray diffraction (XRD). The crystallite sizes calculated from X-rays diffractometric (XRD) results for undoped BaO and Nd-doped BaO were 10.50 nm and 10.04 nm, respectively. The morphological study and percent composition of synthesized NPs were investigated using a scanning electron microscope and energy-dispersive X-ray analysis. Thermogravimetric analysis confirmed the decomposition of precursor to BaO after annealing at ~ 500 °C. The band gap energy calculated for undoped BaO was 3.7 eV. The substitution of Nd to BaO decreased this value to 3.4 eV. The activation energy calculated for the doped BaO and undoped BaO was 16.5 kJ/mol and 22.5 kJ/mol, respectively. The Nd-doped BaO degraded about 96.4% dye, while the undoped BaO NPs degraded about 86.6% dye within 120 min. The synthesized BaO NPs were used as novel catalysts for the photodegradation of malachite green (MG) dye by varying irradiation time, catalyst dose, pH, temperatures and dye initial concentration. The maximum degradation efficiency was achieved at pH 4, catalyst dose 10 mg, dye initial concentration 50 ppm, and at a temperature of 50 °C. The dye degradation was also studied using the recovered catalysts.