Abstract: The oxidative degradation of 0.1 mmol/L orange G (OG) in Fe2+/H2O2、Fe2+/S2O82－、Fe2+/H2O2-S2O82－ was studied. In the Fe2+/H2O2 reaction, under the optimum condition (pH=3, [H2O2]0=10 mmol/L and [Fe2+]0=1 mmol/L), OG degradation in aqueous solutions with initial concentration of 0.1 mmol/L reached 96% within 30 min. However, retardation was observed if H2O2 was overdosed. Such retardation was not observed in the Fe2+/S2O82－ system, but a nonlinear increment of removal efficiency was identified. Degradation of OG was enhanced with increasing S2O82－ initial concentration but decreased at the presence of hydroxyl ion. In the aqueous system of initial pH value of 3, the optimal operation condition of Fe2+/H2O2-S2O82－ was determined to be H2O2 concentration 2 mmol/L. OG degradation increased with increasing dosage of persulfate. Furthermore，it was experimentally found that the Fe2+/H2O2-S2O82－ process on the other hand showed the best mineralization in OG degradation. The sulfate free radical and hydroxyl free radical produced in the system were determined by molecular probes (ethanol and nitrobenzene) methods, and the reaction mechanism of producing sulfate free radical in the Fe2+/H2O2-S2O82－ system was discussed．

Key words: sulfate radical, orange G；sodium persulfate, hydrogen peroxide

摘要： 以偶氮染料橙黄G（OG）为目标污染物，研究Fe2+分别催化H2O2、S2O82－、H2O2-S2O82－降解0.1 mmol/L OG Fe2+/H2O2体系，[Fe2+]=1 mmol/L, pH=3, [H2O2]0=10 mmol/L,降解30 min OG脱色率为96%，随着pH值增大和[H2O2]0＞10 mmol/L，OG脱色率减小，呈线性变化。Fe2+/S2O82－体系，随着S2O82－初始浓度增加OG脱色率增大，随着pH值增大OG脱色率减小，呈非线性变化。Fe2+/H2O2-S2O82－体系，pH=3, [H2O2]0=2 mmol/L， [S2O82－]0＞10 mmol/L时OG脱色率持续增大。Fe2+/H2O2-S2O82－体系矿化率最高。利用乙醇和硝基苯作为分子探针，采用分子探针竞争实验鉴定该体系中产生的SO4?和OH?。

关键词: 硫酸根自由基, 橙黄G, 过硫酸钠, 过氧化氢