Scattering Effects Produced By Inert Particles In Photochemical Reactors. 1. Model And Experimental Verification

During the past 10 years increasing attention has been paid to heterogeneous photochemical systems, considering their eventual uses not only in industrial synthesis of chemical products but mainly in their applications related to solid photocatalyzed reactions particularly addressed to photodegradat...

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Bibliographic Details
Published in:Industrial & engineering chemistry research 1995-02, Vol.34 (2), p.488-499
Main Authors: Alfano, Orlando M, Negro, Antonio C, Cabrera, Maria I, Cassano, Alberto E
Format: Article
Language:English
Subjects:
540120 > Environment, Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
540320 > Environment, Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ABSORPTION
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMICAL REACTORS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ENVIRONMENTAL SCIENCES
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATHEMATICAL MODELS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
POLLUTANTS
RADIATIONS
SCATTERING
SORPTION
VISIBLE RADIATION
YIELDS 400500 > Photochemistry
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Summary:During the past 10 years increasing attention has been paid to heterogeneous photochemical systems, considering their eventual uses not only in industrial synthesis of chemical products but mainly in their applications related to solid photocatalyzed reactions particularly addressed to photodegradation of air and water polluted streams. The radiation field in a planar participating and reacting medium was studied. A one-dimensional model with azimuthal symmetry was employed to investigate radiation absorption and scattering phenomena in the reaction space. The mathematical model was solved numerically, and the results were compared with experimental data obtained in a perfectly mixed, isothermal, batch reactor with recycle. Inside the reactor the well-known oxalic acid homogeneous photodecomposition was conducted and scattering was artificially produced by addition of different amounts of small particles of silica that are chemically inert and transparent to radiation in the investigated wavelength range. Model predictions and experiments have good agreement. They demonstrate that scattering in a well-stirred system always produces a decrease in the volume-averaged reaction rate when compared with a purely absorbing system. According to the relative magnitude of the absorption and scattering contributions, there are cases where radiation losses produced by scattering may bring about a significant reduction in the rate of the homogeneous reaction.
ISSN:0888-5885
1520-5045
DOI:10.1021/ie00041a009