POSSIBLE MECHANISM OF SONOCATALYTIC ACTIVATION OF POTASSIUM PEROXYDISULFATE FOR THE DEGRADATION OF SAFRANIN T DYE

The stable structure of dyes, their low capacity for biodegradation, the removal of pollutants without their mineralization are significant obstacles to the application of many physico-chemical and biological methods of purification of aquatic environments from dyes. Innovative methods that ensure the mineralization of harmful organic pollutants in water systems, including dyes, are advanced oxidation processes based on the use of secondary oxidants (reactive oxygen species) obtained as a result of activation of primary oxidants (hydrogen peroxide, ozone, potassium persulfate, sodium percarbonate, periodates, etc.), which effectively attack pollutant molecules, contributing to their intensive degradation. The efficiency of dye degradation is determined by the number of reactive oxygen species, which depends on the efficiency of activation of the primary oxidant. Potassium peroxydisulfate (K2S2O8) was chosen as the primary oxidant for safranin T dye degradation, which was activated in an ultrasonic cavitation field and by MnFe2O4 spinel nanoparticles (sonocatalytic activation). It was found that as the temperature of the reaction medium increased from 393 to 433 K, the degree of dye degradation increased from 77.7 to 98.3 %, which indicated the important role of temperature as the third factor in the activation of K2S2O8. It was found that the oxidative degradation of safranin T is most accurately described by the kinetic equation of the second-order reaction. The maximum value of the rate constant of oxidative degradation of safranin T was 40.8971 M-1s-1 under the following conditions of experimental research: pH = 3; the initial concentration of the aqueous solution of safranin T was 57.06·10-6 mol/dm3; initial concentration of potassium peroxydisulfate — 5.706 mmol/dm3; catalyst loading — 0.1 g/dm3; the specific power of ultrasonic cavitation treatment was 51 W/dm3. The main reactive oxygen species (singlet oxygen, hydroxyl radicals, sulfate radical anions) were identified using the “spin traps” method, of which singlet oxygen was the dominant oxygen form.