Degradation of Azo Dye C.I. Reactive Blue 194 in Water by Sponge Iron in the Presence of Ultrasound

Abstract Degradation of the azo dye C.I. Reactive Blue 194 (RB 194) by sponge iron in the presence of ultrasound (sponge iron-US) has been investigated, and an evident synergistic effect was observed. Degradation of the dye RB 194 followed pseudo-first-order kinetics. The degradation rate constants by sponge iron, ultrasonic irradiation, and sponge iron-US were 0.00494, 0.0200, and 0.138 min−1, respectively. Effects of operating parameters such as the dosage and particle size of sponge iron, initial pH of the solution, ultrasonic power, and the dye initial concentration on the degradation rate of the RB 194 were investigated. Results showed that the degradation rate of the RB 194 increased with increasing the sponge iron dosage and decreased with increasing the particle size of sponge iron, initial dye concentration, and the initial pH of the solution. The main degradation products of the dye RB 194 were tentatively identified by a gas chromatograph with a mass spectrometer and ion chromatography and a po...