Effective Removal of Methylene Blue by Mn3O4/NiO Nanocomposite under Visible Light

Abstract

Wastewater treatment is indispensable as wastewater can lead to adverse health effects and deteriorate the quality of life on earth. Photocatalysis is a facile methodology to address this issue. In this study, nanocomposites (NCs) of manganese oxide (Mn3O4) and nickel oxide (NiO) were synthesized in different weight ratios via the solid-state reaction route. Structural properties, optical properties, surface morphology, and functional group analysis of the synthesized nanomaterials were conducted using X-ray diffraction (XRD), UV– Vis spectroscopy, scanning electron microscopy (SEM) along with energy-dispersive X-ray (EDX) analysis, and Fourier-transform infrared (FTIR) spectroscopy, respectively. The bandgap of the nanocomposite decreases significantly from 2.35 eV for the Mn3O4 NPs to 1.65 eV for the Mn3O4/NiO nanocomposite (NC). Moreover, adsorption studies followed by the photocatalytic performance of the Mn3O4/NiO NCs were evaluated to determine the removal of methylene blue (MB) dye from wastewater. The photocatalytic performance of the nanocomposite enhances as the ratio of Mn3O4 in the composite increases from one weight percentage to three weight percentage. The photocatalytic degradation efficiency was calculated to be 95%. The results show that the synthesized NCs could play an important role in photocatalytic wastewater purification and environmental remediation.

Synthesis and Characterizations of Fe-Doped NiO Nanoparticles and Their Potential Photocatalytic Dye Degradation Activities

“…The wide peak at 3440 cm −1 and the narrow peak are responsible for the OH stretching on the material surfaces. The bands at 1620 and 1381 cm −1 represent the primary and secondary stretching of C-O and C-H bending, which are related to the reduction of metal ions and the association of lattice oxygen from the synthesized nanoparticles [40,41]. The metal-O bond of the Ni-O band vibrations were observed at 560 cm −1 .…”

“…The minor peaks at around 2350 cm −1 indicate the presence of carbon-group association with the inorganic metal compounds [40][41][42]. Furthermore, the peaks at 1097-1118 cm −1 [40][41][42] revealed lattice oxygen with organic-compound C-O stretching. There were no peaks observed in the 2% and 5% Fe-doped NiO nanoparticles at the range of 500-600 cm −1 due to the least integration of Fe ions into the NiO crystal lattice.…”

“…Fe dopants increased the energy of NiO nanoparticles and induced the electrons which were located at the NiO surfaces. The Fe-NiO nanoparticles' OH-stretching vibrations were found in the bands 3428-3450 cm −1 [40]. In the Fe-NiO nanoparticles, the bands at 2901-2921 cm −1 represent the CH-stretching and the bands at 1574-1626 cm −1 represent the stretching vibrations of the C=O group [40].…”

“…In the Fe-NiO nanoparticles, the bands at 2901-2921 cm −1 represent the CH-stretching and the bands at 1574-1626 cm −1 represent the stretching vibrations of the C=O group [40]. The minor peaks at around 2350 cm −1 indicate the presence of carbon-group association with the inorganic metal compounds [40][41][42]. Furthermore, the peaks at 1097-1118 cm −1 [40][41][42] revealed lattice oxygen with organic-compound C-O stretching.…”

“…The Fe-NiO nanoparticles' OH-stretching vibrations were found in the bands 3428-3450 cm −1 [40]. In the Fe-NiO nanoparticles, the bands at 2901-2921 cm −1 represent the CH-stretching and the bands at 1574-1626 cm −1 represent the stretching vibrations of the C=O group [40]. The minor peaks at around 2350 cm −1 indicate the presence of carbon-group association with the inorganic metal compounds [40][41][42].…”