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The present work presented a novel approach for the degradation of binary Eosin B (EB) and Malachite green (MG) dyes and single dyes using undoped and potassium doped tin oxide (K-SnO2) nanoparticles (NPs) under UV irradiation. The NPs were synthesized using the co-precipitation method. Studies based on multi-dye systems, are hardly available and do not give any detailed reasons for different behaviors of dyes towards the photocatalyst and of the level of degradation. The prepared nanomaterials were identified through Thermal Gravimetric Analysis (TGA), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), UV–Visible (UV–VIS), X-ray diffraction analysis (XRD), and Fourier transform infrared (FTIR) spectroscopy. SnO2 and K-SnO2 optical band gaps were calculated to be 3.5 eV and 3.7 eV respectively. The points of zero charge for both SnO2 and K-SnO2 were calculated to be 4. The XRD results showed that the SnO2 and K-SnO2 particles were crystalline, with mean sizes of 17.13 nm and 10 nm, respectively. The maximum degradation efficiency of the catalyst for MG dye degradation was 99% and that of EB was 77%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cadmium oxide (CdO) and potassium (K) doped CdO nanoparticles (NPs) were synthesized by the chemical co-precipitation method and were used as photocatalysts for the degradation of Eosin B dye. The X-ray diffraction results presented that the crystallite size of undoped CdO and K doped CdO NPs were 43.74 and 42.31 nm, respectively. The morphological study and percent composition of synthesized undoped CdO and K doped CdO NPs was done by scanning electron microscope and energy dispersive X-ray analysis. The formation of NPs was confirmed by Fourier transform infrared spectroscopy. The precursor decomposition to CdO after annealing at ∼500 °C was studied by thermogravimetric analysis. The undoped CdO and K doped CdO nanoparticles degraded about 80% and 90% of the dye, respectively, in 140 min. The maximum degradation efficiency of the dye was achieved at a pH of 4, dye initial concentration of 15 ppm, catalyst dose of 20 mg, and a temperature of 45 °C. The degradation efficiency observed for recovered undoped CdO and recovered doped CdO nanoparticles was found to be 63% and 77%, respectively. [ABSTRACT FROM AUTHOR]

Nanosized ZnO and Cr-doped ZnO nanoparticles (NPs) were prepared by co-precipitation method, which were employed as photocatalysts for the degradation of murexide dye in aqueous media. The nanoparticles were characterized by FTIR, SEM, XRD and TGA. The morphological study illustrated that both ZnO and Cr-doped ZnO NPs are irregular round shaped. The XRD results presented that the crystallite size of undoped ZnO and Cr-doped ZnO were 30.07 and 28.14 nm, respectively. The band gap of undoped ZnO and Cr-doped ZnO were 3.4 and 3 eV, respectively. The precursor decomposition to ZnO after annealing at ∼500 °C was confirmed by TGA. The photodegradation study presented that the Cr-doped ZnO and undoped ZnO NPs degraded about 92 and 89% dye within 100 min, respectively. The effect of different parameters like dye initial concentration, contact time, pH and temperature on the photocatalytic degradation of dye was studied. The activity of recovered catalyst was also studied. [ABSTRACT FROM AUTHOR]

The manganese oxide (MnO 2 and iron-doped manganese oxide (Fe–MnO 2) nanoparticles (NPs) with reduced band gap (Eg) were fabricated through the co-precipitation process. They used to degrade Indigo Carmine (IC) and Rhodamine B (RB) binary mixture in an aqueous medium under solar light irradiation. From FT-IR, the twisting modes of the Mn–O bond and the stretching vibrations of the Fe–Mn–O 2 bond were confirmed from the peaks observed at 480 cm−1,584 cm−1,675 cm−1, and 900 cm−1, 1150 cm−1, and 1200 cm−1 respectively. The MnO 2 has an optical band gap of 3.2 eV, which was decreased to 3 eV in Fe–MnO 2. The zero charge (PZC) point was 8 for Fe–MnO 2 and 7 for MnO 2. The BET surface area for Fe–MnO2 was 398 m2/g, relatively higher than MnO2 particles, having a surface area of 384 m2/g. The average crystallite sizes calculated from Scherer formulae were 37 nm for MnO 2 and 31 nm for Fe–MnO 2 NPs. SEM confirmed the irregular morphology of the prepared particles. It was analyzed that agglomeration occurs in MnO 2 than the Fe–MnO 2. The maximum degradation of IC dye was 99%, and that of RB was 98% at the optimum conditions. The data were best fitted to second-order kinetics. [Display omitted] • Visible light-triggered and recyclable iron-doped manganese oxide (Fe–MnO 2) NPs as photocatalyst. • Morphological and structure tailoring studies was done through advanced techniques. • Photocatalytic degradation of Indigo Carmine (IC) and Rhodamine B (RB) single and binary mixture. • Response surface methodology (RSM) for optimization of degradation process. [ABSTRACT FROM AUTHOR]