The photocatalytic degradation of dyes （Acid Chrome Blue K （ACBK） and Alizarin Red （AR）） with strong complexation ability was investigated in the presence of metal ions under visible light irradiation. It was found that, at low dye-metal ratio, the photodegradation of ACBK was markedly inhibited by the addition of high oxidative potential Cu2＋. However, at high dye-metal ratio, the presence of Cu2＋ enhanced the photodegradation of ACBK. The negtive effect of Cu2＋ on the photodegradation of AR was observed for all dyemetal ratios. The relative chemical inert Zn2＋ tended to enhance the photodegradation of both anionic dyes. The mechanism underlying the different effect of Cu2＋ was discussed from the different roles of surface-adsorbed and dye-coordinated Cu2＋ in the photodegradation of dyes.
The organic-inorganic layered solid catalyst Fe(bpy)_3^(2+)-laponite was ableto photode-grade Rhodamine B (RhB) by activation of dioxygen under visible irradiation (λ > 420nm), while the homogeneous aqueous solution Fe(bpy)_3^(2+) showed no photoactivity. The catalystcould be repeatedly used and retained its reactivity. The hybrid catalyst could be separated fromthe suspension by centrifugation or sedimentation. The TOC removal yield of RhB was measured.Reactive oxygen species (ROS) formed during degradation was detected by EPR. A possible mechanismwas proposed on the basis of the experimental results.
CHENG Mingming1,SUN Zhenying1,2,MA Wanhong1,CHEN Chuncheng1,ZHAO Jincai1 & WANG Zhengping2 1. Laboratory of Photochemistry,Center for Molecular Science,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100080,China
This study investigated the visible-light catalysis mediated by zeolite NaY on the oxidation of dyes with H2O2. The results demonstrated that zeolite NaY acts as a sink for the electron from the photo-excited dye in the heterogeneous catalysis. Furthermore, the electron can effectively activate H2O2 to produce ?OH radical that is a powerful oxidant for the oxidation of dye at room temperature. The effects of the framework topology, Si/Al ratio, and exchangeable cation of the zeolite on the oxidation of various dyes were also shown.
LIU LiLi1, MA WanHong1, SONG WenJing1, CHEN ChunCheng1, LIN Jun2, ZHAO JinCai1, QIAN XinHua3 & ZHANG ShiBo3 1 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
The coupled nanocrystalline ZnO/ZnS was fabricated and immobilized in Nafion membrane by using sodium sulfide （Na2S） as the single anion precursor. The molar ratio of ZnO to ZnS can be controlled by simply adjusting the reaction time. The as-prepared ZnO/ZnS-Nafion samples were characterized by various methods, including optical absorption, X-ray diffraction and high-resolution transmission electron microscopy. These coupled ZnO/ZnS nanocrystals embedded in Nafion membrane displayed excellent photocatalytic activities for their efficient charge separation properties. A mechanism of ZnO/ZnS nanoparticle fabrication in Nafion was deduced from the solubility difference, and the photocatalytic mechanism of coupled ZnO/ZnS was discussed as well.
