Kinetic Study of the Visible Light-Induced Sonophotocatalytic Degradation of MB Solution in the Presence of Fe/TiO₂-MWCNT Catalyst

Abstract

In order to effective degradation of organic dye both under visible light or ultrasonic irradiation, the MWCNTs (multiwalled carbon nanotube) deposited with Fe and TiO2 were prepared by a modified sol-gel method. The Fe/TiO2-MWCNT catalyst was characterized by surface area of BET, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) and ultraviolet-visible (UV-vis) spectroscopy. The low intensity visible light and low power ultrasound was as an irradiation source and the methylene blue (MB) was choose as the model organic dye. Then degradation experiments were carried out in present of undoped TiO2, Fe/TiO2 and Fe/TiO2-MWCNT catalysts. Through the degradation of MB solution, the results showed the feasible and potential use of Fe/TiO2-MWCNT catalyst under visible light and ultrasonic irradiation due to the enhanced formation of reactive radicals as well as the possible visible light and the increase of ultrasound-induced active surface area of the catalyst. After addition of H2O2, the MB degradation rates have been accelerated, especially with Fe/TiO2-MWCNT catalyst, in case of that the photo-Fenton reaction occurred. The sonophotocatalysis was always faster than the respective individual processes due to the more formation of reactive radicals as well as the increase of the active surface area of Fe/TiO2-MWCNT catalyst.

Double Walled Carbon Nanotube/TiO2 Nanocomposites for Photocatalytic Dye Degradation

“…There were significant differences in crystallite sizes with increasing amounts of DWCNTs in the nanocomposites (Table 1). Similar studies on Fe/TiO 2 -MWCNT composites reported average crystallite size of 5 nm [29]. Optical properties of the nanocomposites are shown in Figure 4(a).…”

Ultrasonically induced ZnO–biosilica nanocomposite for degradation of a textile dye in aqueous phase

“…On the other hand, hydroxyl radicals generated via the sonocatalysis is easily transferred to the surface of the ZnO-biosilica nanocomposite, degrading the adsorbed MB molecules. In fact, the immobilized ZnO nanostructures create photoactive centers for the generation of e À /h + pair, whereas the biosilica supplies active adsorption sites in the vicinity of the sonocatalyst [28,30]. This enhances the potential of the sonocatalyst to efficiently adsorb both dye molecules and the light irradiation produced during the cavitation.…”

“…With increasing the initial pH, the surface of the sonocatalyst will be deprotonated, enhancing the attraction force between the cationic dye and negatively charged sonocatalyst. As an another reason, the generation of OH Å radicals as a result of the reaction between the generated h + and OH À ions will be increased at basic conditions [28]. Besides, the sharp decrease in color removal (%) at strong acidic pH (pH = 3) may be due to the corrosion of the sonocatalyst in acidic conditions.…”

“…In the case of ''sonoluminescence'' phenomenon, the ultrasonic irradiation may lead to the creation of the light irradiation with a wide wavelength range due to the cavitation [28], exciting the semiconductor to act as a photocatalyst for the generation of electron-hole pairs and subsequently, OH Å radicals as represented in the following equations [9]:…”

Sonophotocatalytic Performance of Bi2Se3-Graphene/TiO2Hybrid Nanomaterials Synthesized with a Microwave-assisted Method

“…In the case of a nanosized Bi 2 Se 3 and TiO 2 nanocrystal line coupled graphene based photcatalyst system, coupling of two such semiconductors has a beneficial role in improving charge separation and extends TiO 2 in response to visible light compared with our previous experiment results. 34) A mechanism for the degradation of pollutants on a Bi 2 Se 3 coupled TiO 2 catalyst under visible light irradiation and ultrasonic irradiation is shown in Fig. 9.…”