Engineering Support Contract-Team QinetiQ North America, Kennedy Space Center, FL 32899, USA.
J Air Waste Manag Assoc. 2011 Sep;61(9):932-40. doi: 10.1080/10473289.2011.596746.
The objective of this study was to determine whether ultraviolet-light-emitting diodes (UV-LEDs) could serve as an efficient photon source for heterogeneous photocatalytic oxidation (PCO). An LED module consisting of 12 high-power UV-A (lambda max = 365 nm) LEDs was designed to be interchangeable with a UV-A fluorescent black light blue (BLB) lamp for a bench scale annular reactor packed with silica-titania composite (STC) pellets. Lighting and thermal properties of the module were characterized to assess its uniformity and total irradiance. A forward current (I(F)) of 100 mA delivered an average irradiance of 4.0 mW cm(-2) at a distance of 8 mm, which is equivalent to the maximum output of the BLB, but the irradiance of the LED module was less uniform than that of the BLB. The LED and BLB reactors were tested for the oxidization of ethanol (50 ppm(v)) in a continuous-flow-through mode with 0.94 sec residence time. At the same average irradiance, the UV-A LED reactor resulted in a lower CO2 production rate (19.8 vs. 28.6 nmol L(-1) s(-1)), lower ethanol removal (80% vs. 91%), and lower mineralization efficiency (28% vs. 44%) than the UV-A BLB reactor. Ethanol mineralization was enhanced with the increase of the irradiance at the catalyst surface. This result suggests that reduced ethanol mineralization in the LED reactor relative to the BLB reactor at the same average irradiance could be attributed to the nonuniform irradiance over the photocatalyst, that is, a portion of the catalyst was exposed to less than the average irradiance. The potential of UV-A LEDs may be fully realized by optimizing the light distribution over the catalyst and utilizing their instantaneous "on" and "off" feature for periodic irradiation. Nevertheless, our results also showed that the current UV-A LED module had the same wall plug efficiency (WPE) of 13% as that of the UV-A BLB, demonstrating that UV-A LEDs are a viable photon source both in terms of WPE and PCO efficiency.
本研究旨在确定紫外发光二极管（UV-LED）是否可用作多相光催化氧化（PCO）的有效光子源。设计了一个由 12 个高功率紫外-A（lambda max = 365nm）LED 组成的 LED 模块，可与紫外-A 荧光黑光灯（BLB）互换，用于装有硅钛复合（STC）颗粒的台式环形反应器。对模块的照明和热性能进行了表征，以评估其均匀性和总辐照度。在 8mm 的距离处，正向电流（I(F)）为 100mA 时，平均辐照度为 4.0mW cm(-2)，这相当于 BLB 的最大输出，但 LED 模块的辐照度不如 BLB 均匀。在相同的平均辐照度下，在 0.94 秒停留时间的连续流动模式下，LED 和 BLB 反应器用于氧化 50ppm(v)的乙醇。在相同的平均辐照度下，紫外-A LED 反应器的 CO2 生成速率（19.8 比 28.6nmol L(-1) s(-1)）较低，乙醇去除率（80%比 91%）较低，矿化效率（28%比 44%）较低UV-A BLB 反应器。随着催化剂表面辐照度的增加，乙醇矿化作用增强。该结果表明，在相同的平均辐照度下，与 BLB 反应器相比，LED 反应器中乙醇矿化作用的降低可能归因于催化剂上非均匀的辐照度，即一部分催化剂的辐照度低于平均辐照度。通过优化催化剂上的光分布并利用其瞬时“开”和“关”特性进行周期性辐照，UV-A LED 的潜力可能得到充分发挥。然而，我们的结果还表明，当前的 UV-A LED 模块具有与 UV-A BLB 相同的墙壁插电效率（WPE）13%，这表明 UV-A LED 在 WPE 和 PCO 效率方面都是可行的光子源。
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