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首页> 外文期刊>Applied Catalysis, B. Environmental: An International Journal Devoted to Catalytic Science and Its Applications >Photocatalytic degradation of various types of dyes (Alizarin S, Crocein Orange G, Methyl Red, Congo Red, Methylene Blue) in water by UV-irradiated titania
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Photocatalytic degradation of various types of dyes (Alizarin S, Crocein Orange G, Methyl Red, Congo Red, Methylene Blue) in water by UV-irradiated titania

机译：紫外线照射的二氧化钛在水中光催化降解各种类型的染料（茜素S，番红花橙G，甲基红，刚果红，亚甲基蓝）

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摘要

The photocatalytic degradation of five various dyes has been investigated in TiO_2/UV aqueous suspensions. It was attempted to determine the feasilibility of such a degradation by varying the chemical structures, either anthraquinonic (Alizarin S (AS)), or azoic (Crocein Orange G (OG), Methyl Red (MR), Congo Red (CR)) or heteropolyaromatic (Methylene Blue (MB)). In addition to a prompt removal of the colors, TiO_2/UV-based photocatalysis was simultaneously able to fully oxidize the dyes, withy a complete mineralization of carbon into CO_2. Sulfur heteroatoms were converted into innocuous SO_4~(2-) ions. The mineralization of nitrogen was more complex. Nitrogen atoms in the -3 oxidation state, such as in amino-groups, remain at this reduction degree and produced NH_4~+ cations, subsequently and very slowly converted into NO_3~- ions. For azo-dye (OG, MR, CR) degradation, the complete mass balance in nitrogen indicated that the central -N=N-azo-group was converted in gaseous dinitrogen, which is the ideal issue for the elimination of nitrogen-containing pollutants, not only for environmental photocatalysis but also for any physicochemical method. The aromatic rings weree submitted to successive attacks by photogenerated OH~centre dot radicals leading to hydroxylated metabolites before the ring opening and the final evolution of CO_2 induced by repeated subsequent "photo-Kolbe" reactions with carboxylic intermediates. These results suggest that TiO_2/UV photocatalysis may be envisaged as a method for treatment fo diluted colored waste waters not only for decolorization, but also for detoxification, in particular in textile industries in semi-arid countries.
机译：在TiO_2 / UV水性悬浮液中研究了五种不同染料的光催化降解。尝试通过改变化学结构来确定此类降解的可行性，这些化学结构可以是蒽醌（Alizarin S（AS））或偶氮（Crocein Orange G（OG），甲基红（MR），刚果红（CR））或杂多芳族化合物（亚甲基蓝（MB））。除了迅速消除颜色外，基于TiO_2 / UV的光催化同时能够完全氧化染料，而不会将碳完全矿化成CO_2。硫杂原子被转化为无害的SO_4〜（2-）离子。氮的矿化更为复杂。处于-3氧化态的氮原子（如氨基基团）保持此还原度并生成NH_4〜+阳离子，随后缓慢地转化为NO_3〜-离子。对于偶氮染料（OG，MR，CR）的降解，氮气中的完全质量平衡表明中心-N = N-偶氮基团已在气态二氮中转化，这是消除含氮污染物的理想问题，不仅用于环境光催化，还用于任何物理化学方法。芳环经受开环之前光生的OH-中心点自由基的连续攻击，导致羟基化的代谢产物，以及随后通过与羧酸中间体的重复“光-科尔比”反应诱导的CO_2的最终释放。这些结果表明，TiO 2 / UV光催化可以被认为是用于处理稀释的有色废水的方法，不仅用于脱色，而且用于脱毒，特别是在半干旱国家的纺织工业中。

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