Abstract

Studies on the sonolysis of a wide range of organic compounds have demonstrated that ultrasonic irradiation has potential for decomposition of organic pollutants in hazardous wastewater. However, the ultrasonic irradiation alone cannot provide high enough rate of decomposition to be used practically. One of the solutions to increase the degradation efficiency is to combine the ultrasound application with other advanced chemical oxidation processes (AOPs).

In this study, in order to increase the efficiency of ultrasonically assisted degradation of organic pollutants in water, we examined effects of three kinds of solid Fe-containing catalysts, namely iron powder, basic oxygen furnace (BOF) slag and mill scale on the degradation rate of 4-CP (4-chlorophenol) in aqueous solutions containing hydrogen peroxide. In the experiments, 4-CP was considered as a model organic compound. All three Fe-containing matters when react with hydrogen peroxide are involved in the Fenton-like reaction system, which is one of the promising AOPs. The results showed that both the iron powder and mill scale additions can accelerate the degradation of 4-CP, although the effect is dependent on the solution pH. All 4-CP could be decomposed for 2 min at pH = 3 and for 1 h at pH = 5.6. On the other hand, the BOF slag had no catalysis effect on the 4-CP degradation because of higher concentration of calcium and lower concentration of iron.

Keywords: Sonochemical decomposition; Fenton-like system; Advanced chemical oxidation processes (AOPs); 4-Chlorophenol; Fe-containing powder

Article Outline

1. Introduction

2. Experimental

2.1. Material

2.2. Experimental apparatus

2.3. Experimental conditions and procedure

2.4. Sample analysis

3. Results and discussion

3.1. Experiments without solid catalysts

3.2. Experiments with solid catalysts

3.2.1. Effect of iron powder addition

3.2.2. Fenton-like systems

3.2.2.1. Effect of pH and H₂O₂ addition

3.2.2.2. Consideration on the ultrasound irradiation effects

3.2.2.3. Effect of BOF slag and mill scale addition

4. Conclusions

References