Photocatalytic degradation of unsymmetrical dimethylhydrazine on TiO(2)/SBA-15 under 185/254 nm vacuum-ultraviolet.
Photocatalytic degradation of unsymmetrical dimethylhydrazine on TiO(2)/SBA-15 under 185/254 nm vacuum-ultraviolet.
复制标题
185/254 nm真空紫外光催化降解TiO2/SBA-15上不对称二甲肼
作者：
采用原位水热法合成了TiO 2/SBA-15，并首次将其用于真空紫外光催化降解偏二甲肼（UDMH）。由于直接光解、间接光氧化和光催化氧化的协同作用，VUV光催化剂的光降解效率高于紫外光下的光催化剂。所合成的TiO 2/SBA-15催化剂具有有序的介孔结构和稳定的TiO 2相。钛含量、初始pH值和底物浓度对UDMH的真空紫外光降解有影响。其中，Ti/Si摩尔比为1：3的TiO 2/SBA-15（TS-2）在真空紫外光下表现出最好的光催化活性，其速率常数为0.02511 min-1，是VUV/P25的1.91倍。TS-2的上级光催化活性主要与其比表面积和TiO 2含量之间的良好平衡有关。随着偏二甲肼初始浓度的增加，光降解效率降低，在pH 9.0时降解率最大。在VUV/TS-2工艺中，stecOH比stecO 2-对偏二甲肼的降解作用更大，降解途径包括断键、酰胺化、异构化和氧化反应。TS-2还表现出良好的重复使用性，5次循环后的速率常数保持在90%以上，并在自来水中表现出令人满意的降解效率。
In this work, TiO2/SBA-15 was synthesized via an in situ hydrothermal method and was used for vacuum-ultraviolet (VUV) photocatalytic degradation of unsymmetrical dimethylhydrazine (UDMH) for the first time. Compared with photocatalysis under UV irradiation, VUV photocatalysis exhibited higher photodegradation efficiency due to the synergetic effect of direct photolysis, indirect photooxidation and photocatalytic oxidation. The synthesized TiO2/SBA-15 catalysts exhibited ordered mesoporous structure and anatase phase TiO2. Titanium content, initial pH and substrate concentration impacted degradation efficiency of UDMH in the VUV photocatalysis process. Among the prepared catalysts, TiO2/SBA-15 with the molar ratio of Ti/Si = 1 : 3 (TS-2) showed the best photocatalytic activity under VUV light, with the rate constant of 0.02511 min−1, which is 1.91 times that with VUV/P25. The superior photocatalytic activity of TS-2 is mainly related to the good balance between the specific surface area and TiO2 contents. The photodegradation efficiency decreases with the increase in the initial UDMH concentration and the maximum degradation rate was obtained at pH 9.0. In the VUV/TS-2 process, ˙OH played a more important role in the degradation of UDMH than ˙O2− and the degradation pathways contained bond breaking, amidation, isomerisation and oxidation reactions. The TS-2 also showed good reusability with the rate constant maintained at above 90% after five cycles and exhibited satisfactory degradation efficiency in tap water.
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