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Kinetics of vanillin oxidation
Author(s) -
Fargues Claire,
Mathias Álvaro,
Silva José,
Rodrigues Alírio
Publication year - 1996
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.270190206
Subject(s) - vanillin , alkalinity , chemistry , oxygen , nuclear chemistry , kinetics , inorganic chemistry , kraft paper , organic chemistry , chemical engineering , physics , quantum mechanics , engineering
Vanillin can be produced by oxidation of kraft lignin, with air, in alkaline medium. The optimal conditions for vanillin production strongly depend on pH and temperature. This paper addresses the effect of temperature and pH on vanillin degradation by oxidation. Experiments were carried out in a wide range of vanillin concentration, oxygen partial pressure, temperature and pH. Simple models are proposed to explain the observed rate of vanillin consumption under conditions of high alkalinity (pH>12) and lower alkalinity (pH<12). At pH>12,the reaction rate of vanillin oxidation is first order in dissolved oxygen concentration [O 2 ] and in vanillin concentration [C], i.e., (− r C ) ∝[O 2 ][C]; at pH<12, the rate is zero order in oxygen concentration and second order in vanillin concentration, i.e., (− r C )∝ f (pH)[C] 2 .