Controlling the Structural Properties and Optical Bandgap of PbO–Al2O3 Nanocomposites for Enhanced Photodegradation of Methylene Blue

Abstract

In the present work, PbO-x wt% Al2O3 nanocomposites (where x = 0, 10, 20, 30, 40, 50, 60, 70, and 100 wt%) were prepared by a microwave irradiation method. Their structural parameters, morphology, and chemical bonds, were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). It was noticed that the produced phases have an orthorhombic crystal structure and the smaller average crystallite sizes were formed when the ratio of Al2O3 is 40 wt%. The FTIR analysis reveals the formation of various bonds between Al or Pb and O. The TEM analysis reveals that the PbO-x%Al2O3 composites (x = 20, 40, and 60), composed of dense particles, and their size are smaller compared to the pure Al2O3 sample. The optical bandgap obeys the direct allowed transition and decreases from 4.83 eV to 4.35 eV as the PbO ratio in the composites increases from 0 to 100%. The intensity of the photoluminescence emission, at the same wavelength, increases as the PbO ratio increases from 0% to 60% implying that increasing the PbO content increases the capacity of free carriers within the trap centers. The prepared composites are used as a catalyst to remove the methylene blue (MB) from the wasted water under UV-visible or visible light irradiations. The photocatalytic degradation of MB was investigated by applying various kinetic models. It was found that the PbO-30% Al2O3, and PbO-40% Al2O3 composites are the best ones amongst other compositions. Furthermore, the pseudo-second-order model is the best model for describing the deterioration mechanism among the models studied. The formed composites could be suitable for the degradation of organic dyes for water purification as well as applications that required a higher optical bandgap.

Facile synthesis of different metals doped α-PbO nanoparticles for photocatalytic degradation of Methylene Blue dye

“…The PbO-modified TiO 2 introduced new electronic states above the valence band maximum of TiO 2 , which enhanced the photocatalytic activity of TiO 2 in the visible light region. Mebed et al [33] prepared PbO-Al 2 O 3 nanocomposites by microwave irradiation method and utilized it for methylene blue dye removal from wastewater under UV-visible or visible light irradiations. The combination of PbO and perovskite photocatalysts has also been reported so far.…”

Boosting photocatalytic activity of β-PbO nanoparticles through metal doping

“…Sn doped showed the highest intensity which indicates weak interaction of Sn-O bond, hence capacity of carriers increases at trap center due the increase of emission intensity peaks [16]. However, Co doped showed weak intensity due to strong interaction between Co and O [28].…”

“…At the same time, electron localization takes place on the surface of TiO 2 , and hole localization takes place on PbO, modifying the photocatalytic activity of TiO 2 . Mebed et al [16] also reported the PbO-Al 2 O 3 nanocomposite synthesized by a microwave irradiation method and utilized for the degradation of methylene blue (MB) dye under UV-vis and visible light irradiation. MB dye is among the synthetic dyes widely used in textile industries which are physically and chemically stable compounds that affect aquatic life when released into the environment without treatment and effective management [7].…”

Experimental and computational study of metal oxide nanoparticles for the photocatalytic degradation of organic pollutants: a review

“…247 On the other hand, PbO 2 and PbO possess good chemical stability, optical transparency, and micro-hardness, which make them suitable for optoelectronic industry applications. 241,248,249 Lead oxide can also be found in the form including Pb 3 O 4 , PbO 2 , Pb 2 O 3 (α, β, and amorphous), and PbO (α, β). 250 PbO nanoparticles have a wide range of applications including energy storage devices, luminescence materials, gas sensors, modifiers in glass, lead crystals, pigments, nanoelectronic devices, lead glazes, UV blockers, pigments, and in decorative potteries.…”

“…PbO has also been used in different metal oxide nanoparticles to modify their photocatalytic activity. Mebed et al 241 prepared PbO–Al 2 O 3 nanocomposite by the microwave irradiation method and utilized it for the removal of methylene blue from wastewater under UV-visible or visible light irradiations. Al 2 O 3 possesses a very wide bandgap of approximately 9 eV.…”