Photosensitized Oxidation of Substituted Phenols on Aluminum Phthalocyanine-Intercalated Organoclay
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- 作者：Zhigang Xiong ; Yiming Xu ; Lizhong Zhu ; and Jincai Zhao
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：January 15, 2005
- 年：2005
- 卷：39
- 期：2
- 页码：651 - 657
- 全文大小：159K
- 年卷期：v.39,no.2(January 15, 2005)
- ISSN：1520-5851
文摘
Bentonite modified with cationic surfactant, cetyltri-methylammonium bromide (CTMA), was an effective sorbentfor organic pollutants in water. To make the sorbentrecyclable, aluminum phthalocyanine (AlPc), a representativephotosensitizer for generation of singlet oxygen, wasinserted successfully into the interlamellar space of CTMA-modified bentonite. Under visible light (
> 450 nm)irradiation, the composite catalyst exhibited a remarkableactivity for degradation of the recalcitrant pollutantsphenol, 4-chlorophenol, 4-nitrophenol, 2,4-dichlorophenol,and 2,4,6-trichlorophenol in an aerated aqueous medium. Theinitial rate of the heterogeneous photoreaction wasfound to increase with the initial amount of the substratesorption onto the catalyst, the kinetics following theLangmuir-Hinshelwood equation. Loading of AlPc intothe organoclay led to slight expansion of the clay basalspacings from 1.82 to 2.15 nm, but the sorption capacity wasdecreased notably. The optimal loading of AlPc wasabout 0.25 wt %. The result demonstrates that the surfactant-modified bentonite not only offers a hydrophobic zonefor enrichment of organic contaminants but also providesa flexible environment for destruction of the sorbedpollutants by singlet oxygen generated in situ. It wasnoted, however, that during four repeated experiments,both the sorption and the degradation rate of 2,4,6-trichlorophenol were gradually decreased, due to someintermediates formed and sorbed onto the catalyst surface.
> 450 nm)irradiation, the composite catalyst exhibited a remarkableactivity for degradation of the recalcitrant pollutantsphenol, 4-chlorophenol, 4-nitrophenol, 2,4-dichlorophenol,and 2,4,6-trichlorophenol in an aerated aqueous medium. Theinitial rate of the heterogeneous photoreaction wasfound to increase with the initial amount of the substratesorption onto the catalyst, the kinetics following theLangmuir-Hinshelwood equation. Loading of AlPc intothe organoclay led to slight expansion of the clay basalspacings from 1.82 to 2.15 nm, but the sorption capacity wasdecreased notably. The optimal loading of AlPc wasabout 0.25 wt %. The result demonstrates that the surfactant-modified bentonite not only offers a hydrophobic zonefor enrichment of organic contaminants but also providesa flexible environment for destruction of the sorbedpollutants by singlet oxygen generated in situ. It wasnoted, however, that during four repeated experiments,both the sorption and the degradation rate of 2,4,6-trichlorophenol were gradually decreased, due to someintermediates formed and sorbed onto the catalyst surface.