Degradation of diazine dye safranin T using potassium persulfate activated by ultrasonic treatment and MnFe2O4 spinel nanoparticles

Abstract

An advanced oxidation process of ultrasound/MnFe2O4/K2S2O8 was developed for the degradation of diazine dye safranin T, according to which potassium persulfate was co-activated by ultrasonic (US) cavitation and MnFe2O4 spinel nanoparticles synthesized via co-precipitation in the ultrasonic field. A synthesis product annealed at a temperature of 4000C, with an average size of MnFe2O4 crystallites of about 7 nm, was used as a catalyst for the decomposition of potassium persulfate. Based on the results of experimental studies on the influence of various factors on the degree and rate constant of safranin T oxidative degradation, as well as considering energy and resource-saving principles, the rational conditions of oxidative degradation were determined as follows: the reaction medium temperature of 600C, the molar ratio of safranin T:K2S2O8=1:100, the catalyst loading of 0.1 g/l, and the specific power of the ultrasonic cavitation treatment of 51.0 W/l. It was established that under such conditions the oxidative degradation degree of safranin T was equal to 98.3%, and the rate constant was 1.510–3 s–1. The changes in the UV-Vis spectra of safranin T, namely a decrease in the intensity of absorption bands, both in the visible (at a wavelength of 520 nm) and in the UV (at a wavelength of 275 nm) regions of the spectrum, confirmed the degradation of safranin T. In addition, the absence of the appearance of new peaks in the visible and UV regions of the spectrum indicated mineralization of the dye.