- Photocatalytic degradation of water taste and odour compounds in the presence of polyoxometalates and TiO2: Intermediates and degradation pathways
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Geosmin (GSM) and 2-methylisoborneol (MIB) are produced by several species of cyanobacteria and actinomycetes. These compounds can taint water and fish causing undesirable taste and odours. Studies have shown that GSM/MIB are resistant in standard water treatments. Polyoxometalates (POM) are efficient photocatalysts in the degradation and mineralization of a great variety of organic pollutants, presenting similar behaviour with the widely published titanium dioxide (TiO2). Photocatalytic degradation of GSM and MIB under UV-A light in the presence of a characteristic POM photocatalyst, SiW 12O404-, in aqueous solution has been studied and compared with the photodegradation by TiO2 suspensions. GSM and MIB are effectively degraded in the presence of both photocatalysts. Addition of OH radical scavengers (KBr and tertiary butyl alcohol, TBA) retards the photodegradation rates of both compounds, suggesting that photodegradation mechanism takes place via OH radicals. Intermediates identified using GC-MS in the case of GSM and MIB, are mainly identical in the presence of both photocatalysts, also suggesting a common reaction mechanism. Possible photocatalytic degradation pathway for both GSM and MIB is proposed.
- Fotiou, Theodora,Triantis, Theodoros M.,Kaloudis, Triantafyllos,Papaconstantinou, Elias,Hiskia, Anastasia
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- Synthesis and electrochemical properties of slipped-cofacial porphyrin dimers of ferrocene-functionalized Zn-imidazolyl-porphyrins as potential terminal electron donors in photosynthetic models
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A systematic series of ferrocene-functionalized Zn-imidazolyl-porphyrins were synthesized to assemble into the slipped-cofacial porphyrin dimers through imidazolyl-to-zinc complementary coordination as artificial photosynthetic models. Direct substitution at the meso position of the porphyrin ring with ferrocence and octamethylferrocene leads to the characteristic electronic structures, while the ferrocene substituents through phenylene-ethenylene and phenylene-ethylene spacers mitigate the electronic communications. Bathochromic shift of Q band, fluorescence quenching, and redox potentials of porphyrin ring are rationalized by the degree of electron-donating ability of the terminal ferrocenes. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Kalita, Dipak,Morisue, Mitsuhiko,Kobuke, Yoshiaki
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- AN IMPROVED SYNTHESIS OF 1,2,3,4,5-PENTAMETHYLCYCLOPENTADIENE
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An inexpensive three-step synthesis for large-scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene is reported.Improvement of Burger's route involving 2,3,5,6-tetrahydro-2,3,5,6-tetramethyl-γ-pyrone and 2,3,4,5,-tetramethylcyclopent-2-enone raised the overall yield to about 34percent of the desired compound (originally 8percent).
- Kohl, Franz X.,Jutzi, Peter
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p. 119 - 121
(2007/10/02)
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