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首页> 外文期刊>Environmental Science & Technology >Photocatalytic Reactors. 3. Kinetics of the Decomposition of Chloroform Including Absorbed Radiation Effects
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Photocatalytic Reactors. 3. Kinetics of the Decomposition of Chloroform Including Absorbed Radiation Effects

机译：光催化反应器。 3.包括吸收辐射效应在内的氯仿分解动力学

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摘要

The rate of decomposition of water pollutants by means of photocatalytic processes can be quantitatively evaluated by using a fully irradiated photoreactor in which the rate of energy absorption is precisely quantified. Using a suspension of titanium dioxide as the active photocatalyst, excess oxygen over the stoichiometric demand, and a mercury arc lamp, we have found that (ⅰ) The rate of photocatalytic decomposition of chloroform in water is of first order with respect to [HCCl_3], zero order with respect to [O_2], and about one-half order with respect to the volumetric rate of energy absorption (VREA). (ⅱ) The effects due to catalyst concentration are accounted for within the VREA dependence. (ⅲ) These findings coincide with a reaction pathway in which, at moderate to high irradiation conditions and in the absence of mass transport limitations, the recombination rate of the photogenerated charge carriers is much faster than the hole trapping by hydroxyl groups attached to surface Ti~Ⅳ atoms (and/or the hole capture by the substrate itself), which are then the rate-determining steps. (ⅳ) The employment of low levels of incident radiation leads to larger quantum efficiencies, the more so if dilute suspensions of the photocatalyst are used.
机译：水污染物通过光催化过程的分解速率可以通过使用完全辐照的光反应器进行定量评估，其中可以精确地量化能量吸收的速率。使用二氧化钛的悬浮液作为活性光催化剂，超出化学计量需求的过量氧气和汞弧灯，我们发现（ⅰ）相对于[HCCl_3]，氯仿在水中的光催化分解速率是一阶的。相对于[O_2]为零阶，相对于能量吸收的体积率（VREA）约为二分之一阶。 （ⅱ）在VREA依赖性内考虑了催化剂浓度引起的影响。 （ⅲ）这些发现与反应路径相吻合，在中等至较高的辐照条件下，并且在没有质量传输限制的情况下，光生电荷载流子的复合速率比通过附着在表面Ti上的羟基捕获空穴要快得多〜Ⅳ个原子（和/或衬底本身捕获的空穴），然后是速率确定步骤。 （ⅳ）使用低水平的入射辐射会导致更大的量子效率，如果使用光催化剂的稀悬浮液则更是如此。

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