Synergistic degradation of dyeing wastewater by the ultrasound/Fenton method

Degradation of simulated reactive red 2 (RR2) wastewater by ultrasonic technology, Fenton reagent oxidation, and a combination of the two processes was studied. It was found that extent of degradation by ultrasonic technology or Fenton reagent oxidation alone was poor, with values of 5% and 45% respectively. The extent of degradation was significantly enhanced when the two processes were combined, with a value of up to 90%, which shows that these two processes have a good synergistic effect. The degradation of RR2 by the combined processes can be described by a second-order kinetics model. The effect of varying factors such as ultrasonic power, pH, and concentration of Fe2+ and H2O2 on the degradation of RR2 was investigated. The results showed that the degradation extent is strongly pH dependent and increases with decreasing pH. The extent of degradation was found to increase with increasing ultrasonic power and FeSO4 concentration below 0.045 mmol/L. Furthermore, it was found that there is an optimal intermediate H2O2 concentration for effective RR2 degradation.