Enhancing Photocatalytic Activity of ZnO Nanoparticles in a Circulating Fluidized Bed with Plasma Jets

Abstract

In this work, zinc oxide (ZnO) nanoparticles were modified in a circulating fluidized bed through argon and hydrogen (Ar–H) alternating-current (AC) arc plasma, which shows the characteristics of nonequilibrium and equilibrium plasma at the same time. In addition, a circulating fluidized bed with two plasma jets was used for cyclic processing. The catalytic degradation performance on Rhodamine B (Rh B) by Ar–H plasma-modified ZnO and pure ZnO was tested in aqueous media to identify the significant role of hydrogen atoms in Rh B degradation mechanism. Meanwhile, the effects of plasma treatment time on the morphology, size and photocatalytic performance of ZnO were also investigated. The results demonstrated that ZnO after 120-min treatment by Ar–H plasma showed Rh B photocatalytic degradation rate of 20 times greater than that of pure ZnO and the reaction follows a first kinetics for the Rh B degradation process. Furthermore, the photocatalyst cycle experiment curve exhibited that the modified ZnO still displays optimum photocatalytic activity after five cycles of experiment. The improvement of photocatalytic activity and luminescence performance attributes to the significant increase in the surface area, and the introduction of hydrogen atoms on the surface also could enhance the time of carrier existence where the hydrogen atoms act as shallow donors.

Green Fabrication of ZnO Nanoparticles and ZnO/rGO Nanocomposites from Algerian Date Syrup Extract: Synthesis, Characterization, and Augmented Photocatalytic Efficiency in Methylene Blue Degradation

“…•OH + MB (on ZnO/rGO) → Degraded Products (10) Throughout this cycle, electrons return to the ZnO nanoparticles to fill the electron vacancies (holes) created during the initial excitation, facilitating the sustained photocatalytic activity of the composite [51].…”

Synthesis of Solar-Sensitive ZnO Photocatalysts Using Microwave Plasma for Effective Degradation of Phenols and Antibiotics

“…This is due to the lack of economically accessible technology for mass production of hybrid photo-catalysts. As an alternative to TiO2, ZnO [11,12], which is not inferior in efficiency and availability, has recently been actively studied. Despite the similarity of the band gap of ZnO (3.37 eV) with TiO2 (3.2 eV), a distinctive feature of the band structure of ZnO is the presence of isolated energy levels in the band gap associated with point defects, mainly oxygen vacancies [13].…”

Oxidation of Zinc Microparticles by Microwave Plasma to Form Effective Solar-Sensitive Photocatalysts

“…This is due to the lack of economically accessible technology for mass production of hybrid photocatalysts. As an alternative to TiO 2 , ZnO [11,12], which is not inferior in efficiency and availability, has recently been actively studied. Despite the similarity of the band gap of ZnO (3.37 eV) with TiO 2 (3.2 eV), a distinctive feature of the band structure of ZnO is the presence of isolated energy levels in the band gap associated with point defects, mainly oxygen vacancies [13].…”