Photocatalytic degradation of malic acid using a thin coated TiO2‐film: Insights on the mechanism of photocatalysis
Photocatalytic degradation of malic acid using a thin coated TiO2‐film: Insights on the mechanism of photocatalysis
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DOI：
10.1002/aic.14500
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发表时间：
2014-09
期刊：
影响因子：
3.7
通讯作者：
V. Rodgher;J. Moreira;H. Lasa;Benito Serrano
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文献类型：
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作者：
V. Rodgher;J. Moreira;H. Lasa;Benito Serrano
使用光催化剂和近紫外线(UV)照射来去除不透明流体的污染面临着重大的技术挑战。这项研究考虑了放置在一个新的化学反应工程中心(CREC)-光反应池中的一层薄的二氧化钛。这种新型的光反应池被用来光催化降解苹果酸和丙二酸，这两种典型的苹果汁成分。有机物种的转化只能通过与流体直接接触的二氧化钛层的“暗面”进行。在选定的操作条件下，外部传质限制和光解都可以忽略不计。宏观辐射平衡表明，92%的近紫外光被TiO2膜的背面吸收。在10、20、30和40ppm苹果酸初始浓度下的光催化降解实验表明，丙二酸是主要的中间体。苹果酸的完全转化发生在辐照后5-8小时。苹果酸和丙二酸光降解的动力学模型和动力学参数估计都是使用“串联”和“串联-并行”反应网络进行的。“串-并”反应网络对CO2的生成有较好的预测能力，最大量子产率为14.2%。考虑到在具有较薄的二氧化钛薄膜的CREC-光反应池中，光催化只能通过将可移动的“h+”位从受光侧转移到“暗侧”来进行，本研究论证了这一步骤对整个光催化机理的意义。©2014美国化学工程师学会学报，60：3286-3299,2014
Decontamination of opaque fluids using photocatalysts and near Ultraviolet (UV) irradiation involves major technical challenges. This study considers a thin TiO2 layer placed in a new Chemical Reactor Engineering Centre (CREC)-photoreactor cell. This new photoreactor cell is used for the photocatalytic degradation of malic and malonic acids, typical apple juice components. Conversion of organic species can only proceed through the “dark side” of the TiO2 layer, which is in direct contact with the fluid. Under the selected operating conditions both external mass-transfer limitations and photolysis are found to be negligible. Macroscopic radiation balance shows that 92% of near UV radiation is absorbed by the ‘back side” of the TiO2-film. Photocatalytic degradation experiments with 10, 20, 30, and 40 ppm malic acid initial concentrations, show that malonic acid is a main intermediate. Complete malic acid conversion occurs after 5–8 h of irradiation. Kinetic modeling of malic and malonic acid photodegradation with kinetic parameter estimation is performed using both an “in series” and an “in series-parallel” reaction networks. The “in series-parallel” reaction network displays better ability for predicting CO2 formation, showing maximum quantum yields of 14.2%. Given that in the CREC-photoreactor cell with a thin TiO2-film, photocatalysis can only proceed via the transfer of mobile “h+” sites from the irradiated side to the “dark side', this study demonstrates the significance of this step on the overall photocatalysis mechanism. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3286–3299, 2014