The poor light transmittance , low recycling rate and potential secondary pollution problems of powder photocatalysts limit the practical application of photocatalytic technology. Therefore, there is an urgent need to develop stable floating photocatalysts to alleviate the problem of harmful algal blooms (HABs). In this work, a floating Ag 2 MoO 4 /TACN@LF composite was synthesized for the inactivation of Microcystis aeruginosa ( M. aeruginosa ) by employing a simple oscillatory impregnation method. The Ag 2 MoO 4 /TACN@LF floating photocatalyst exhibited stable algae removal performance under various conditions, and 100% chlorophyll a removal rate could be achieved within 4 h of visible light irradiation under the optimal photocatalyst loading of 6 g/L. The effects of Ag 2 MoO 4 /TACN@LF floating catalyst on algal cell membrane permeability, phycobiliprotein, intracellular antioxidant enzyme activities and algal organic matter were further studied. Moreover, the scavenging experiments demonstrated that •OH was the predominant reactive oxygen species (ROSs). Ag0 and 3 g-C 3 N 4 * also made a non-negligible contribution to the inactivation of algal cells. What's more, the Ag 2 MoO 4 /TACN@LF still exhibited 92% inactivation efficiency for M. aeruginosa after 5 cycles reused experiments, indicating its promising potential for practical application of alleviating HABs.
Xiaohua Zheng,Huilin Han,Ruomeng Zhang,Jingting Yang
Photocatalysis is a green and efficient technology for degrading organic pollutants. However, its development is restricted by the high recombination rate of photogenerated electron-hole pairs. In this study, double-Z-type BiVO 4 /AgBr/Ag 2 MoO 4 ternary photocatalysts were successfully synthesized by a one-step precipitation method at room temperature, and their photocatalytic performance for degrading rhodamine B (RhB) was investigated. The composition and microstructure of the photocatalysts were characterized by X-ray diffraction (XRD), cold field scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), specific surface area testing, and X-ray photoelectron spectroscopy (XPS). The results of ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) indicate that the optical properties of the photocatalysts are good. Under visible light irradiation, the BiVO 4 /AgBr/Ag 2 MoO 4 photocatalyst with Ag 2 MoO 4 mass fraction of 12% achieved a degradation rate > 99% within 12 min, with degradation rates 260.5, 6.1, and 161.7 times that of pure BiVO 4 , AgBr, and Ag 2 MoO 4 , respectively. In addition, holes (h + ) and superoxide radicals (·O 2− ) are the main active species, and hydroxyl radicals (·OH) also have a certain influence during the photocatalysis process, according to the active species capture experiments. This study demonstrates that the ternary photocatalyst has the potential to efficiently degrade organic pollutants under sunlight.
Yaya Song,Wenyu Xie,Chao Yang,Dandi Wei,Xintai Su,Li Li,Lu Wang,Jide Wang
Herein, Ag/Ag 2 MoO 4 and Ag/Ag 2 WO 4 have been prepared via a humic acid-assisted precipitation-calcination process and used as catalysts for the hydrogenation reduction of nitro- and azo-aromatic compounds. The Ag/Ag 2 MoO 4 and Ag/Ag 2 WO 4 composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) and Raman spectroscopies, UV–vis-NIR diffuse reflectance spectroscopy (DRS), and nitrogen adsorption-desorption analyses. Metallic Ag nanoparticles were in situ generated during the annealing process and spatially confined in the Ag 2 MoO 4 or Ag 2 WO 4 matrix, which effectively inhabited the particle agglomeration of silver. The Ag/Ag 2 MoO 4 and Ag/Ag 2 WO 4 catalysts displayed good performance toward the hydrogenation reduction of 4-nitrophenol, 2-nitroaniline, and rhodamine B in terms of rapid conversion and long term durability.
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