MECHANISM OF PERSULFATE DECOMPOSITION IN AQUEOUS-SOLUTION AT 50-DEGREES IN THE PRESENCE OF METHYL ACRYLATE IN NITROGEN ATMOSPHERE

The rate of thermal decomposition of potassium persulphate (KPS) in aqueous solution in the presence of methyl acrylate (MA), monomer (M) and nitrogen gas, may be written as -d[S2O8(2-)]/dt proportional (S2O8(2-)1.42 +/- 0.06 x (M) 1.15 +/- 0.05, in the concentration ranges of persulphate (0.50-2.0) x 10(-2) mol dm-3 and monomer (M) (1.328-5.313) x 10(-1) mol dm-3, i.e. within its solubility range under the experimental conditions. It has been suggested that persulphate ions oxidise the monomer, and water-soluble monomeric and oligomeric free radicals, (Mj)w [GRAPHICS] where j = 1 to 30; k1 = 1.71 x 10(-6)s-1 and k5 = 1.23 x 10(-5) dm3 mol-1 s-1 where k1 is the rate constant of the irreversible dissociation of persulphate ion, viz. S2O8(2-)--> 2SO4.-; taking ktw, [GRAPHICS] Polymer in the aqueous phase as 3.70 x 10(6) dm3 mol-1, s-1, k10 has been estimated as 1.06 x 10(2) dm3 mol-1 s-1.