Abstract
The kinetics and mechanism of oxidation of alginate polysaccharide (Alg) by alkaline hexacyanoferrate(III) in basic solutions at a constant ionic strength of 1.0 mol dm(-3) have been investigated spectrophotometrically. The experimental results showed complex kinetics, where the reaction time curves of the pseudo first-order plots were found to be of sigmoidal S-shape nature. The initial parts of the plots were relatively fast, followed by slow-linear portions after short time periods. The oxidation rates were increased with increasing the alkali concentration indicating that the oxidation is base-catalyzed. A kinetic evidence for formation of 1:1 intermediate complexes was revealed. The activation parameters have been evaluated and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed. (C) 2014 Elsevier B.V. All rights reserved.