L. Lunar et al., Degradation of photographic developers by Fenton's reagent: Condition optimization and kinetics for metol oxidation, WATER RES, 34(6), 2000, pp. 1791-1802
The potential of the Fenton's reagent for oxidation of p-aminophenols, whic
h are the main developers used in white and black processes, was assessed.
Metol [N-methyl-p-aminophenol] was chosen as a model. Degradation of this c
ompound by Fenton's reagent was examined under dark conditions as a functio
n of reagent concentrations and pH used in batch treatments. Under optimal
conditions, 0.2 M H2O2, 9.0 x 10(-4) M Fe2 +, pH 3-5 and room temperature,
the initial COD of a 5 x 10(-3) M metol solution was reduced by about 50% w
ithin 2 h. After this time, additional COD reduction was very slow (about 2
0% in five days). No aromatic compounds were detected about 4 h of reaction
indicating that residual organic matter was mainly made up of ring cleavag
e products. Metol conversion behaved as a first-order reaction with respect
to metol and Fe2 +. Complete destruction of residual organic matter could
be achieved at high temperatures (about 60 degrees C) or by using the photo
-Fenton reaction, which thus opens up prospects for an effective treatment
of p-aminophenols in effluents from photographic processes. (C) 2000 Elsevi
er Science Ltd. All rights reserved.