Mechanism and kinetic model of the oxidative degradation of Rhodamine B dye in aqueous solution by ultrasound-assisted Fenton's process

A plausible mechanism for sono-Fenton reaction has been proposed and a kinetic model was developed with verification by experimental data. Degradation of Rhodamine B dye using sono-Fenton process has been investigated. Effects of initial pH, initial dye concentration, dosage of FeSO4, H2O2 and ultrasonic power density were studied. Optimum values were: pH = 3, H2O2 = 2.74 x 10(-2) mol/dm(3), FeSO4 = 3.60 x 10(-4) mol/dm(3). Maximum 99.57% decolourisation and 69.41% COD reduction were obtained in 30 minutes. Sono-Fenton process was more efficient than dark-Fenton or sonolysis under the same conditions. Decolourisation rate increased with increase in initial dye concentration up to 7.30 x 10(-4) mol/dm(3) after which it decreased. Similarly, the maximum decolourisation rate was obtained at 2.74 x 10(-2) mol/dm(3) of H2O2. Decolourisation increased with increasing FeSO4 dosage and ultrasonic power density. Initial rate was influenced by initial dye concentration, ultrasonic power density and the initial dosage of H2O2 and FeSO4.