KINETIC-STUDY OF THE OXIDATION OF INDIGOCARMINE BY HYDROGEN-PEROXIDE WITH FERROUS AND FERRIC IONS IN ACID-MEDIUM

The use of hydrogen peroxide in addition to ferrous and ferric salts h as been shown an effective method in the decoloration of indigocarmine (IDS), Indigo- 5,5'-disulfonic acid disodium salt. The kinetic experi ments control have been carried out by means of a conventional spectro photometric technique. In acid medium and the initial absence of Fe+2, the decoloration process obeys the following rate law: -d[IDS]/dt = k (exp.)[IDS] Effects of reagents concentrations, temperature, and acidi ty on the rate experimental constant have been discussed. A feasible r eaction mechanism is finally proposed. The rate equation deducted from the mechanism is according to the achieved experimental results. (C) 1997 John Wiley and Sons, Inc.