A facile synthesis of undoped and 2.0 % selenium-doped zinc oxide nanoparticles (NPs) was efficaciously accomplished through a mechanochemical route using zinc acetate dihydrate, oxalic acid, and Se powder in a solid state reaction. After calcination at 450 °C, the obtained nanostructures were probed by X-ray diffraction, where the acquired data revealed the pertinence of the wurtzite hexagonal ZnO for both undoped (ZnO) and doped (Se/ZnO) NPs and crystallite sizes of 30 and 24 nm for ZnO and Se/ZnO, respectively. The formation of the target NPs was confirmed by the scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and the Fourier transformation infrared molecular vibrations data. The porosity investigations indicated 33.65 m²/g Brunauer–Emmett–Teller surface area, 197 Å pore diameter, and 0.172 cm³/g pore volume for the Se/ZnO NPs compared to lower values for the pristine ZnO. The band gap energies were 3.19 and 3.15 eV for ZnO and Se/ZnO as perceived from the Tauc plots of the UV-visible absorption measurements. The photodegradation of methylene blue dye under UV illumination was found to follow the pseudo–first-order kinetics with an enhanced performance by the doped samples as reflected by the higher (3.2 × 10⁻³ s⁻¹) rate constant relative to the undoped sample (1.7 × 10⁻³ s⁻¹). A photodegradation mechanism was suggested in the light of the band gap energy investigation. The obtained findings indicate the improvement of ZnO properties by doping with Se through a simplistic and inexpensive approach.

Herein the degradation of malachite green (MG) dye from aqueous medium by vanadium-doped zinc oxide nanopowder was investigated. The specific surface area and pore volume of the nanopowder was characterized by nitrogen adsorption method. Batch experimental procedures were conducted to investigate the adsorption and photocatalytic degradation of MG dye. Adsorption kinetics investigations were performed by varying the amount of the catalyst and the initial dye concentrations. Adsorption and photocatalytic degradation data were modeled using the Lagergreen pseudo-first-order and second-order kinetic equation. The results showed that the ZnO:V_3% nanopowder was particularly effective for the removal of MG and data were found to comply with Lagergreen pseudo-first-order kinetic model.

Here, we demonstrate a pyrolysis route for the synthesis of flower buds like magnesium oxide nanoparticles using a magnesium carbonate precursor without additional chemicals. The effect of heating at different time intervals upon the structure and morphology of the acquired nanostructures were investigated via X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Fourier transformation infrared spectroscopy. Nitrogen adsorption was employed to study its porosity. The obtained data confirmed the formation of target nanoparticles that exhibited increasing sizes as pyrolysis time was lengthened. As a consequence a high surface area up to 27 m² g⁻¹ was recorded for the sample heated for 1 h duration. Furthermore, Indigo Carmine dye adsorption was carried out using the largest surface area species which showed an adsorption capacity of 158 mg g⁻¹. The adsorption was found to comply with the Langmuir isotherm and it follows the pseudo-second-order kinetics. The diffusion process showed intra-particle along with film diffusion mode.

This article deals with the removal of cobalt ions using zinc oxide nanopowder. The nanomaterial was prepared via the sol–gel method under supercritical drying. The nanomaterial was characterised via XRD, SEM, EDX, FTIR, and BET surface area techniques. The kinetics, equilibrium, and thermodynamic studies of the metal ions adsorption on the nanomaterial were conducted in batch mode experiments by varying some parameters such as pH, contact time, initial ion concentrations, nanoparticles dose, and temperature. The data revealed significant dependence of the adsorption process on concentration, and the temperature was found to enhance the adsorption rate indicating an endothermic nature of the adsorption. The adsorption complied well with the pseudo-second-order kinetics model. The adsorption process was found to match the Langmuir adsorption isotherm. The ZnO nanoparticles could successfully remove up to 125 mg·g⁻¹ of Co(II) ions at elevated temperature. The metal ions adsorption could be described as an endothermic, spontaneous physisorption process. A mechanism for the metal ions adsorption was proposed.