Different inactivation Behaviors of MS-2 phage and Escherichia coli in TiO2 photocatalytic disinfection
Different inactivation Behaviors of MS-2 phage and Escherichia coli in TiO2 photocatalytic disinfection
复制标题
DOI：
10.1128/aem.71.1.270-275.2005
复制
发表时间：
2005-01-01
影响因子：
4.4
通讯作者：
Yoon, JY
中科院分区：
文献类型：
--
作者：
Cho, M;Chung, HM;Yoon, JY
尽管有大量的实验证据证明了与TiO2光催化反应相关的生物杀灭作用的有效性，但我们对这种特殊的生物杀灭作用的光化学机制的理解仍然很不清楚。普遍认为，在紫外光照射下，二氧化钛表面产生的羟基自由基(-OH)起主要作用。然而，我们对羟基自由基杀灭微生物的确切作用方式的了解还远不完全，一些研究报道了其他活性氧物种(ROS)(H_2O_2和O(2)(.-)等)。也扮演着重要的角色。特别是，羟基自由基是仍然结合在表面上还是扩散到溶液中，这是一个活跃的争论。为了研究ROS在灭活微生物中的确切作用方式，我们分别测试和比较了MS-2噬菌体和大肠杆菌作为病毒和细菌的代表物种的光催化灭活水平。为了比较光催化微生物灭活和光催化化学降解反应，以对氯苯甲酸作为探针化合物，对氯苯甲酸能以扩散限制的速度与羟基自由基反应。用叔丁醇和甲醇两种不同的羟基自由基清除剂和本体相产生羟基自由基的活化剂Fe2+，研究了它们对羟基自由基光催化作用方式的影响。结果表明，ROS的生物杀灭作用模式因所涉及的特定微生物而有很大不同，尽管原因尚不清楚。似乎MS-2噬菌体主要被溶液中的自由基灭活，而大肠杆菌则同时被自由基和表面结合的羟基自由基灭活。根据目前的结果，大肠杆菌也可能被其他ROS灭活，如O-2(.-)和过氧化氢。
Despite a wealth of experimental evidence concerning the efficacy of the biocidal action associated with the TiO2 photocatalytic reaction, our understanding of the photochemical mechanism of this particular biocidal action remains largely unclear. It is generally accepted that the hydroxyl radical (-OH), which is generated on the surface of UV-illuminated TiO2 plays the main role. However, our understanding of the exact mode of action of the hydroxyl radical in killing microorganisms is far from complete, and some studies report that other reactive oxygen species (ROS) (H2O2 and O(2)(.-)etc.) also play significant roles. In particular, whether hydroxyl radicals remain bound to the surface or diffuse into the solution bulk is under active debate. In order to examine the exact mode of action of ROS in inactivating the microorganism, we tested and compared the levels of photocatalytic inactivation of MS-2 phage and Escherichia coli as representative species of viruses and bacteria, respectively. To compare photocatalytic microbial inactivation with the photocatalytic chemical degradation reaction, para-chlorobenzoic acid, which rapidly reacts with a hydroxyl radical with a diffusion-limited rate, was used as a probe compound. Two different hydroxyl radical scavengers, tert-butanol and methanol, and an activator of the bulk phase hydroxyl radical generation, Fe2+, were used to investigate their effects on the photocatalytic mode of action of the hydroxyl radical in inactivating the microorganism. The results show that the biocidal modes of action of ROS are very different depending on the specific microorganism involved, although the reason for this is not clear. It seems that MS-2 phage is inactivated mainly by the free hydroxyl radical in the solution bulk but that E. coli is inactivated by both the free and the surface-bound hydroxyl radicals. E. coli might also be inactivated by other ROS, such as O-2(.-) and H2O2, according to the present results.