Development of a Hg-free UV light source incorporating a Kr/Br2 gas, and its application for wastewater treatments
Development of a Hg-free UV light source incorporating a Kr/Br2 gas, and its application for wastewater treatments
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DOI：
10.1007/s43630-020-00006-6
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发表时间：
2021-01
影响因子：
3.1
通讯作者：
U. Chitete-Mawenda;N. Serpone;S. Horikoshi
中科院分区：
文献类型：
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作者：
U. Chitete-Mawenda;N. Serpone;S. Horikoshi
汞灯通常是水处理中的主要光源。然而，汞的使用引起了《关于汞的水俣公约》的一些担忧。因此，已经用 Kr/Cl2、Xe/Cl2 和 Kr/Br2(R/H) 等无汞混合填充气体研究了包含稀有气体和卤素气体 (R/H-MDEL) 的无汞微波放电无电极灯 (MDEL)。其中，只有 Kr/Br2-MDEL 灯在受到微波辐射照射时在 15 Torr 的内压下会自燃。因此，我们制造了一种新型 Kr/Br2 三层 MDEL (Kr/Br2-MDEL) 光反应器，以评估最佳气体成分和气压，以评估其处理水介质中被柠檬黄染料和大肠杆菌污染的模型废水的性能。柠檬黄染料的降解程度和大肠杆菌的灭菌程度。随着微波辐射功率（100、200 和 300 W）以及样品流速从 0.4 L min−1 增加到 0.8 L min−1，大肠杆菌随着辐照时间的延长而增加。将柠檬黄污染的废水以 0.4 L min−1 的流量通过三种不同的方案处理微波照射 60 分钟，产生 UV (62%) >> UV/ROS (24%) > ROS (0%)； ROS表示活性氧。在同样以 0.4 L min−1 照射大肠杆菌废水 5 分钟后，顺序为 UV (99.5%) ≈ UV/ROS (99.3%) >> ROS (14.5%)。为了比较，E.的光灭菌。使用等效 Hg/Ar-MDEL 光源的大肠杆菌也几乎完整（99.7%）。因此，环境友好的 Kr/Br2 气体填充物替代 MDEL 中的 Hg/Ar 填充气体的适用性已得到证明，可用于水介质中有机污染物的光消除和微生物消毒。
Mercury lamps are typically the major light sources in water treatments. However, the use of mercury has raised some concerns with regard to the Minamata Convention on Mercury. As such, Hg-free microwave discharged electrodeless lamps (MDELs) that incorporate a rare gas and a halogen gas (R/H-MDEL) have been investigated with such Hg-free mixture filler gases as Kr/Cl2, Xe/Cl2, and Kr/Br2(R/H). Of these, only the Kr/Br2-MDEL lamp is self-ignited at an inner pressure of 15 Torr when irradiated with microwave radiation. Accordingly, a novel Kr/Br2three-layer MDEL (Kr/Br2-MDEL) photoreactor was fabricated to assess the optimal gas composition and gas pressure toward its performance vis-à-vis the treatment of model wastewaters contaminated with the tartrazine dye in aqueous media and withEscherichia coli(E. coli) bacteria. The extent of degradation of the tartrazine dye and sterilization ofE. coliincreased with irradiation time, with microwave radiation power (100, 200, and 300 W), and with increased sample flow rate 0.4 L min‒1to 0.8 L min‒1. The tartrazine-contaminated wastewater was treated at a flow rate of 0.4 L min‒1for 60 min of microwave irradiation by three different protocols that resulted in UV (62%) >> UV/ROS (24%) > ROS (0%); ROS denotes reactive oxygen species. After 5 min irradiation of theE.coliwastewater, also at 0.4 L min‒1, the order was UV (99.5%) ≈ UV/ROS (99.3%) >> ROS (14.5%). For comparison, the photosterilization ofE. coliwith an equivalent Hg/Ar-MDEL light source was also nearly complete (99.7%). Thus, the suitability of the environmentally friendlier Kr/Br2gas fill to replace Hg/Ar filler gas in MDELs for the photoelimination of organic pollutants and microbial disinfection in aqueous media has been demonstrated.