Degradation behavior of mixed and isolated aromatic ring containing VOCs: Langmuir-Hinshelwood kinetics, photodegradation, in-situ FTIR and DFT studies
Degradation behavior of mixed and isolated aromatic ring containing VOCs: Langmuir-Hinshelwood kinetics, photodegradation, in-situ FTIR and DFT studies
复制标题
含有 VOC 的混合和分离芳环的降解行为：Langmuir-Hinshelwood 动力学、光降解、原位 FTIR 和 DFT 研究
DOI：
10.1016/j.jece.2021.105069
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发表时间：
2021-01-28
影响因子：
7.7
通讯作者：
Sun, Jing
中科院分区：
文献类型：
--
作者：
Mahmood, Asad;Wang, Xiao;Sun, Jing
以TiO2P25为模型光催化剂，研究了苯、甲苯、对二甲苯等混合VOCs和单独VOCs的光降解趋势。不同有机污染物的存在对混合气体中VOCs的降解有显著影响。例如，苯在混合物中的降解率仅为10%，而在隔离模式下的降解率为67%。苯与对二甲苯和甲苯混合时的转化率分别为20%和27%。结果表明，对二甲苯的存在比甲苯对苯的降解性影响更大。化学计量比和缺陷二氧化钛表面的动态吸附-脱附实验和密度泛函理论计算表明，苯与化学计量比二氧化钛表面的相互作用弱于甲苯和对二甲苯。这一行为可能是苯降解率较低的根本原因。此外，二氧化钛表面氧空位(Ov)的存在极大地改善了对VOCs的整体吸附。采用基于不同反应动力学假设的几种Langmuir-HinShelwood动力学模型确定了反应速率、水吸附平衡常数和VOCs吸附平衡常数。结果表明，VOCs的氧化发生在催化剂表面，且VOCs的吸附平衡常数大于水的吸附平衡常数。通过原位FTIR研究，进一步对中间体的生成和羟基的消耗进行了合理化。本工作对混合模式和分离模式下VOCs的降解进行了全面的分析，为光催化氧化技术在VOCs治理中的应用提供了可能。
The photodegradation tendencies of mixed and isolated VOCs, e.g., benzene, toluene, andp-xylene were studied using TiO2 P25 as a model photocatalyst. The degradation of VOCs in the mixture is significantly affected by the existence of different organic pollutants. For example, benzene only showed 10% degradation efficiency in the mixture whilst 67% in the isolated mode. The conversion efficiency of benzene was 20% and 27% when mixed with p-xylene and toluene, respectively. It shows that the degradability of benzene is influenced more by the presence of p-xylene than toluene. The dynamic adsorption-desorption experiments and DFT calculations on stoichiometric and defective TiO2 surface revealed that benzene only weakly interacts with the stoichiometric TiO2 surface than toluene and p-xylene. This behavior could be the fundamental factor for the lower degradation efficiency of benzene. Furthermore, the presence of oxygen vacancy (Ov) in TiO2 surface tremendously improved the overall adsorption of VOCs. Several Langmuir-Hinshelwood kinetic models, which are based on different reaction dynamic assumptions, were used to determine rates of reactions, water adsorption equilibrium constant, and VOCs adsorption equilibrium constant. The results indicated that the oxidation of VOCs occurred on the catalyst surface, and the adsorption equilibrium constant of VOCs was higher than water adsorption equilibrium constant. The intermediate formation and hydroxyl groups consumption were further rationalized via in-situ FTIR study. This work provides a comprehensive analysis of VOCs degradation in the mixed and isolated mode, which will increase the possibility of implementing the photocatalytic oxidation technology for the VOCs abatement.