Removal of 2,4-Dichlorophenol by Fluidized-bed Fenton process

The degradation of 2,4-dichlorophenol (2,4-DCP) by fluidized-bed Fenton process has been optimized by using experimental design methodology. Box-Behnken design was applied to investigate the effects of pH, the amount of carriers, initial H2O2 and initial Fe2+ concentration on the treatment performance in terms of 2,4-DCP, chemical oxygen demand (COD) and total iron removal efficiencies. Results showed that H2O2 concentration had more profound effect than Fe2+ in terms of 2,4-DCP removal while, pH and the amount of carriers did not have an obvious effect on 2,4-DCP degradation. Increasing H2O2 concentrations could improve COD removal whereas increasing Fe2+concentration more than 0.55 mM would decrease COD removal. The decreased COD performance was probably due to hydroxyl radical scavenging effects. Results also revealed the optimum condition for degrade 2,4-DCP, from the Box-Behnken design prediction: pH 3, 100 g of SiO2, 0.25 mM of Fe2+ and 10 mM of H2O2. Under this conditions, 2,4-DCP, COD and total iron removal efficiencies were > 99, 55 and 14%, respectively. Additionally, the total iron removal efficiency at the optimum condition in fluidized-bed Fenton was higher than that in Fenton process. This result demonstrates the advantage of fluidized-bed Fenton process compared with the traditional Fenton technology.