Photocatalyzed N-demethylation and degradation of methylene blue in titania dispersions exposed to concentrated sunlight
Photocatalyzed N-demethylation and degradation of methylene blue in titania dispersions exposed to concentrated sunlight
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DOI：
10.1016/s0927-0248(01)00215-x
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发表时间：
2002-07
影响因子：
6.9
通讯作者：
Tianyong Zhang;T. Oyama;S. Horikoshi;H. Hidaka;Jincai Zhao;N. Serpone
中科院分区：
文献类型：
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作者：
Tianyong Zhang;T. Oyama;S. Horikoshi;H. Hidaka;Jincai Zhao;N. Serpone
采用抛物面圆形聚光反应器（PRCR），在太阳光照射下，对模拟亚甲基蓝（MB）废水进行光催化脱色。当浓度随时间的变化是集中光照射能量的函数时，动力学分析进行得很好。MB的光催化N-脱甲基化与MB的光催化分解通过伪一级动力学同时发生。光分解动力学对MB初始浓度的依赖性符合Langmuir-Hinshelwood模型。TOC（总有机碳）的消除也发生在完全漂白的水性TiO 2分散体之前的伪一级动力学，之后的TOC水平仅略有下降。与空气中相比，光照条件下分子氧连续鼓泡通过反应物悬浮液对亚甲基蓝的光降解没有影响。TiO 2负载量和流速对MB的降解有显著影响。在聚光太阳光下，亚甲基蓝光降解的相对光子效率为0.49（相对于苯酚）。MB降解的效率曲线与光反应器的几何形状（圆柱形瓶反应器与圆底烧瓶）、光源（太阳光集中器与汞灯）和所使用的操作模式（流动与分批操作）无关。
S imulated wastewaters that con tain methylene blue (MB) were bleached in a photocatalytic aqueous TiO2dispersion illuminated by concentrated sunlight using a parabolic round concentrator reactor (PRCR). The kinetic analysis was carried out well when the temporal concentration variation was a function of the concentrated light energy irradiated. The p hotocatalyzed N-demethylation of MB takes place concurrently with photocatalytic decomposition of MB by pseudo- first-order kinetics. The dependence of the photo- decomposition kinetics on the initial concentration of MB is consistent with the Langmuir– Hinshelwood model. Elimination of TOC (total organic carbon) also occurs by pseudo- first-order kinetics prior to full bleaching of the aqueous TiO2dispersion, after which the TOC level decreases only slightly. Also, compared with the open to air, the photodegradation of MB is not influenced by molecular oxygen bubbl ing continuously through the reactant suspensions during illumination . TiO2loadings and flow rates markedly a ffect the degradation o f MB. Under concentrated sunlight, t he relative photonic efficiency of MB photodegradation i s ζrel=0.49 (relative to phenol) . T he efficiency ζrelfor the degradation of MB is independent of photoreactor geometry (cylindrical bottle reactor versus round-bot tomed flask), of light sources (solar light concentrator versus a Hg lamp) and of the operating mode used (flow versus batch operation).