Oxidation of Starch by H2O2 in the Presence of Iron Tetrasulfophthalocyanine Catalyst: The Effect of Catalyst Concentration, pH, Solid-Liquid Ratio, and Origin of Starch
Résumé
Several types of starches were oxidized by H2O2 in the presence of iron
tetrasulfophthaloryanine catalyst (FePcS) in batch mode, and the
kinetics of the H2O2 decomposition was followed when varying the
catalyst concentration and solid to liquid ratio of the starch and
aqueous phase. Mainly, waxy corn starch with high content of amylopectin
and potato starch were used, but also high amylose,starch was studied.
The COOH content was determined for the final oxidized starch. It was
found that, with 40 mg of catalyst and the starch present in a larger
amount, the H2O2 decomposition followed a first order kinetics with an
initial decomposition rate in the range of 0.10 mol/L.h. Significantly
less starch slowed down the decomposition rate to 0.05 mol/L.h; however,
when no starch was present, the decomposition increased to a maximum of
0.14 mol/L. On the contrary, absence of catalyst resulted in a linear
H2O2 decomposition profile. The FePcS catalyst concentration had a large
impact on the decomposition of H2O2 regardless of the starch amount or
the starch origin. When using very low starch amounts in relation to the
catalyst amount, brown,solid residues were observed on the reactor
wall, indicating that iron was defragmented from the catalyst.