Ma. Salem et al., CATALYTIC-OXIDATION OF P-NITRODIPHENYLAMINE WITH PEROXYDISULFATE IN MICELLAR AND NONMICELLAR MEDIA, Journal de chimie physique et de physico-chimie biologique, 90(5), 1993, pp. 1201-1217
The kinetics of oxidation of p-nitrodiphenylamine (p-NO2-DPA) with the
peroxydisulphate ion has been investigated spectrophoto-metrically. T
he uncatalyzed oxidation process was so slow but was accelerated treme
ndously upon the incorporation of Ag+ as catalyst. At moderate concent
ration of the catalyst, the reaction proceeds with first order kinetic
s with respect to the substrate, oxidant and catalyst concentrations.
In the presence of high concentration of Ag+, the order of reaction fo
r the substrate species turned to zero, resulting in an overall second
order reaction consisting of first order kinetics for the Ag+ and S2O
82- individually. Sodium dodecyle sulphate (SDS) micelles showed furth
er enhancement in the catalyzed reaction rate when its concentration w
as less-than-or-equal-to 3 x 10(-3) M. Above this limit an inhibition
occurred. Such enhancement has not been observed with cetyltrimethylam
-monium bromide (CTAB) but only a retardation was observed. Mixed solu
tion of both SDS and CTAB also inhibited the rate considerably. Mechan
isms describing the oxidation processes have been suggested.