| Nowdays, the pollution control and prevention of refractory organics is one of the new challenges in the field of water treatment. Application of radiation technology in environmental protection is a novel and promising research field, and has been received increasing attention. Theγ-radiolysis of chlorophenols (CPs) in aqueous solution, including its effect factors and kinetics characters was investigated using the 60Coγ-irradiation source. The main conclusions can be drawn as follows:The efficiency of the radiation-induced degradation of CPs depends on several factors, such as the absorbed dose, initial CP concentration, pH value, different gases, free radicals scavengers as well as the molecular structure of CP. The experimental results indicated that theγ-irradiation treatment is an efficient technology for the degradation of CPs in aqueous solutions. When the initial concentration was 50 mg/L and the radiation dose was 6 kGy, the degradation efficiencies of 4-CP and PCP were 96.1% and 100%, respectively. At the same radiation dose, lower initial CP concentration and sufficient oxygen supply could increase the degradation efficiency of CPs, and lower pH was favorable for 4-CP degradation. The existence of ?OH scavenger had a significant negative impact on the radiolytic degradation of CPs, which reveals that ?OH plays a very important role in the radiolysis of CPs in water. When the initial concentration of CPs was 100 mg/L and the radiation dose was 8 kGy, the removal efficiencies of 2-CP, 3-CP, 4-CP, 2,4-DCP were 68.0%, 97.5%, 89.7% and 100% respectively, and the corresponding dechlorination efficiencies were 60.2%, 71.1%, 64.3% and 78.9%, respectively. The removal and dechlorination efficiencies of different CPs in water were both in the following order: 2,4-DCP>3-CP>4-CP>2-CP, which reveals that the molecular structure has a strong impact on the radiation degradation of CPs.Kinetics study showed that the radiolytic degradation of CPs was in accordance with the pseudo-first-order kinetic model. The lower initial CP concentration had a higher dose constant. When the dose rate was 10.84 Gy/min and the initial concentration was 100 mg/L, the dose constants (kGy-1) of CPs degradation were in the following order: 2,4-DCP(0.6761)>3-CP(0.3908)>4-CP(0.2807)>2-CP(0.1360). In the experiment of PCP radiation degradation in water, the power function relationship between the dose rate (d) and the initial concentration (C0) was firstly found: d=25.4496C0-0.9539.The degradation of 4-CP by usingγ-ray in the presence of O3 and H2O2 were investigated. The kinetics of 4-CP mineralization was analyzed based on the determination of total organic carbon (TOC). The results showed that the degradation of TOC could also be described by first-order reaction model. The combination ofγ-radiation and O3/H2O2 oxidation resulted in synergistic effect, which can remarkably increase the degradation efficiency of 4-CP.Although the removal of TOC was not significant especially when the initial CP concentration was higher, the 8~15 kGyγ-irradiation could decrease the biotoxicity of the 75mg/L PCP solution immensely. It indicates that it is practical to apply biological treatment after suitableγ-irradiation at certain dose, which may reduce the required absorbed dose significantly. The combined process will be a promising means for removal of refractory organics from aqueous solution.
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