Liang Hai-Chao, Li Xiang-Zhong, Yang Yin-Hua, Sze Kong-Hung
Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Chemosphere. 2008 Oct;73(5):805-12. doi: 10.1016/j.chemosphere.2008.06.007. Epub 2008 Jul 21.
In this study, the highly-ordered TiO(2) nanotube (TNT) arrays on titanium sheets were prepared by an anodic oxidation method. Under UV illumination, the TNT films demonstrated the higher photocatalytic activity in terms of 2,3-dichlorophenol (2,3-DCP) degradation in aqueous solution than the conventional TiO(2) thin films prepared by a sol-gel method. The effects of dissolved oxygen (DO) and pH on the photocatalytic degradation of 2,3-DCP were investigated. The results showed that the role of DO in the 2,3-DCP degradation with the TNT film was significant. It was found that 2,3-DCP in alkaline solution was degraded and dechlorinated faster than that in acidic solution whereas dissolved organic carbon removal presented an opposite order in dependence of pH. In the meantime, some main intermediate products from 2,3-DCP degradation were identified by a (1)H NMR technique to explore a possible degradation pathway. A major intermediate, 2-chlororesorcinol, was identified from the 2,3-DCP decomposition as a new species compared to the findings in previous reports. Photocatalytic deactivation was also evaluated in the presence of individual anions (NO(3)(-), Cl(-), SO(4)(2-), and H(2)PO(4)(-)). The inhibition degree of photocatalytic degradation of 2,3-DCP caused by these anions can be ranked from high to low as SO(4)(2-)>Cl(-)>H(2)PO(4)(-)>NO(3)(-). The observed inhibition effect can be attributed to the competitive adsorption and the formation of less reactive radicals during the photocatalytic reaction.
在本研究中，采用阳极氧化法在钛片上制备了高度有序的TiO₂纳米管（TNT）阵列。在紫外光照射下，与通过溶胶 - 凝胶法制备的传统TiO₂薄膜相比，TNT薄膜在水溶液中对2,3 - 二氯苯酚（2,3 - DCP）降解表现出更高的光催化活性。研究了溶解氧（DO）和pH值对2,3 - DCP光催化降解的影响。结果表明，DO在TNT薄膜对2,3 - DCP的降解中作用显著。发现碱性溶液中的2,3 - DCP比酸性溶液中的降解和脱氯更快，而溶解有机碳的去除则呈现出相反的pH依赖性顺序。同时，通过¹H NMR技术鉴定了2,3 - DCP降解的一些主要中间产物，以探索可能的降解途径。与先前报道的结果相比，从2,3 - DCP分解中鉴定出一种主要中间产物2 - 氯间苯二酚作为新物种。还在存在单个阴离子（NO₃⁻、Cl⁻、SO₄²⁻和H₂PO₄⁻）的情况下评估了光催化失活。这些阴离子对2,3 - DCP光催化降解的抑制程度从高到低依次为SO₄²⁻＞Cl⁻＞H₂PO₄⁻＞NO₃⁻。观察到的抑制作用可归因于光催化反应过程中的竞争吸附和低活性自由基的形成。
