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Wet oxidation of active carbon
Author(s) -
Charest F.,
Chornet E.
Publication year - 1976
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450540312
Subject(s) - chemistry , mass transfer , reaction rate constant , kinetics , reaction rate , carbon fibers , redox , activation energy , oxygen , carbon dioxide , chemical kinetics , order of reaction , reaction mechanism , kinetic energy , thermodynamics , inorganic chemistry , catalysis , materials science , organic chemistry , chromatography , physics , quantum mechanics , composite number , composite material
As a preliminary step to studies on the regeneration of active carbon, its wet oxidation has been followed in order to obtain information about the different parameters involved: agitation, temperature and pressure. The oxidation reaction takes place in the liquid phase and it does not proceed at significant rates below 200°C, even with high initial oxygen pressures. The oxidation proceeds rapidly beyond 275°C at pressures as low as 30 atm. The only detectable reaction product is carbon dioxide. Although mass transfer effects are minimized at stirring speeds higher than 400 rpm, a visible abrasion of the carbon was apparent beyond 300 rpm. Consequently, the study was carried out at around 200 rpm. Mass transfer effects had to he considered then. Estimation of the different transfer coefficients was done from the experiments and through existing correlations. In this way the kinetics could be obtained. The rate of reaction can be represented by a first order kinetic expression. Comparison of the rates has been done at fixed conversions. The intrinsic rate constant has a surprisingly low activation energy of 8.4 Kcal/mole suggesting that the oxidation reaction proceeds via a free radical mechanism. The overall rates show a maximum at conversions varying between 0.10 and 0.40. The specific surface area decreases regularly with reaction time, indicating that the reaction takes place throughout the particle.