Kinetic study on TEMPO-mediated selective oxidation of regenerated cellulose

The kinetics of the TEMPO-mediated oxidation of regenerated celluloses has been studied. It is revealed that the oxidation reaction of the regenerated celluloses by the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO)–NaBr–NaOCl system can be approximately described by first-order kinetics with respect to substrate. In the concentration range used the rate constant k is directly proportional to the concentration of TEMPO, while it is proportional to the concentration of NaBr in a relatively lower range and tends to level off at higher concentration. The effect of temperature on the rate constant can be well described by the Arrhenius equation, the apparent activation energy measured is about 66.2 kJ/mol. The effect of the pH of the reaction solution, the crystallinity and morphology of the substrates on the oxidation rate is also discussed.