The degradation efficiency and kinetic degradation reaction of Ponceau 6R dye using
potassium chromate have been investigated under various experimental conditions: different concentrations
of H2SO4 and temperatures. The immediate change of the red coloration
(kmax= 518 nm) to colorless was observed after addition of inorganic oxidizing agent (K2CrO4)
into the protonated form of Ponceau 6R dye after 48 h. This observation could be attributed to
the highest oxidized form of this dye obtained (the quinoid one), which undergoes a hydrolysis reaction
to produce p-hydroquinone (H2Q) by a mechanism similar to Schiff-base hydrolysis. The cationic
form of this matrix is a crucial feature for the hydrolysis process. A kinetic model for
oxidation of Ponceau 6R by the combination of chromate was developed based on experimental
results. The observed kinetic reaction coefficient was determined and correlated as a function of
UV spectral intensity of Ponceau 6R at 518 nm. The degradation rate follows pseudo-first order
kinetics with respect to dye concentration.