CATALYTIC-OXIDATION OF P-NITRODIPHENYLAMINE WITH PEROXYDISULFATE IN MICELLAR AND NONMICELLAR MEDIA

The kinetics of oxidation of p-nitrodiphenylamine (p-NO2-DPA) with the peroxydisulphate ion has been investigated spectrophoto-metrically. The uncatalyzed oxidation process was so slow but was accelerated tremendously upon the incorporation of Ag+ as catalyst. At moderate concentration of the catalyst, the reaction proceeds with first order kinetics with respect to the substrate, oxidant and catalyst concentrations. In the presence of high concentration of Ag+, the order of reaction for the substrate species turned to zero, resulting in an overall second order reaction consisting of first order kinetics for the Ag+ and S2O82- individually. Sodium dodecyle sulphate (SDS) micelles showed further enhancement in the catalyzed reaction rate when its concentration was 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 solution of both SDS and CTAB also inhibited the rate considerably. Mechanisms describing the oxidation processes have been suggested.