title: Degradation of Acid Orange 7 using magnetic AgBr under visible light: the roles of oxidizing species.
abstract: AgBr was creatively immobilized on a magnetic substrate (SiO(2)-coated Fe(3)O(4) nanoparticle, SFN) to achieve magnetic separation after visible light-driven photocatalytic oxidation (PCO). The resulted Ag/AgBr/SFN was characterized by TEM, vibrating sample magnetometer and other techniques. It is found that the average diameter of the Ag/AgBr/SFN particle is less than 20 nm. The typical superparamagnetic behavior of Ag/AgBr/SFN implies that the catalyst can be magnetically separated. The physicochemical features of the used Ag/AgBr/SFN after visible light irradiation were not dramatically changed by X-ray diffraction, UV-Vis diffuse reflectance spectra and Fourier transform-infrared analysis. SiO(2) interlayer was proven to slightly increase the degradation efficiency for an azo dye Acid Orange 7. UV-Vis spectra and HPLC analysis indicated that the dye was oxidized and decomposed. The photoactivity of Ag/AgBr/SFN was partly maintained after successive PCO under visible light. In order to evaluate the roles of e(-)-h(+) pairs and reactive oxygen species, the quenching effect was examined by employing Ag/AgBr/SFN and commercial TiO(2) (P-25) under visible light (lambda>400 nm) and UV-A irradiation, respectively. Active h(+) and the resulting (*)OH played the major roles for degradation. The effect of active h(+) and (*)OH were proven to be highly dependent on the concentration of photocatalysts. The effect of (*)OH was more obvious for P-25, while that of active h(+) was more predominant for Ag/AgBr/SFN.
authors: Department of Biology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China.
authors: Guoting
authors: G
authors: Li
authors: K H
authors: KH
authors: Wong
authors: Xiwang
authors: X
authors: Zhang
authors: Chun
authors: C
authors: Hu
authors: Jimmy C
authors: JC
authors: Yu
authors: R C Y
authors: RC
authors: Chan
authors: P K
authors: PK
authors: Wong
mesh_terms: D001391:Azo Compounds / Q000737:chemistry / Q000378:metabolism*; D001557:Benzenesulfonates / Q000737:chemistry / Q000378:metabolism*; D001965:Bromides / Q000737:chemistry*; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism*; D052918:Environmental Restoration and Remediation; D008027:Light; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry; D010084:Oxidation-Reduction; D010777:Photochemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D001965:Bromides; D004396:Coloring Agents; D017382:Reactive Oxygen Species; D018030:Silver Compounds; C047751:silver bromide; C014722:2-naphthol orange