纳米α-Fe2O3/H2O2异相Fenton 催化降解酸性橙7

Degradation of Acid Orange 7 in Nano-α-Fe2O3/H2O2 Heterogeneous Fenton System

摘要:

研究以水热法制备纳米α-Fe2O3，并应用于异相Fenton体系中催化降解酸性橙7，探究其催化机理。使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)鉴定样品结构；在异相Fenton催化体系中，通过优化初始pH、初始底物浓度、双氧水添加量、α-Fe2O3添加量、温度，探究合适的催化降解条件，通过多次循环催化对催化剂稳定性进行研究，并通过催化过程中产生的自由基，分析其催化机理。实验结果表明，α-Fe2O3为长约70 nm，宽约20 nm的均匀单一纳米棒。在异相Fenton催化体系中，最佳催化条件为初始pH 3.0，初始底物浓度200 mg/L，反应温度为30℃，双氧水的添加量为1.5%，催化剂α-Fe2O3添加量为500mg/L，在反应120 min时脱色率为98.74%，COD去除率为73%；稳定性良好，铁离子溶出量低于0.8 mg/L，循环实验5次脱色率始终在90%以上，此外，对自由基的研究表明，HO?在本体系降解过程中占主要作用。

Abstract:

In this paper, nano-α-Fe2O3 was synthesized by a facile hydrothermal method, and further utilized as heterogeneous Fenton catalysts for the degradation of acid orange 7. The mechanism of nano-α-Fe2O3/H2O2 system was investigated. The structural properties of α-Fe2O3 was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed that α-Fe2O3 exhibited a rod-like morphology with a width of 20 nm and a length of 70 nm. To optimize the operating parameters, the effects of initial pH, substrate concentration, H2O2 concentration, catalyst loading, and reaction temperature in the degradation of acid orange 7 were studied. With the optimized experimental conditions (initial pH = 3.0, substrate concentration = 200 mg/L, H2O2 concentration = 1.5%, catalyst loading = 50 mg/L, and reaction temperature = 30 篊), the degradation rate of acid orange 7 and COD were up to 98.74% and 73%, respectively, after 120 min. The cyclic stability of α-Fe2O3 was evaluated. It was confirmed that the α-Fe2O3 exhibited excellent stability. No significant catalyst deactivation was noted in the five successive runs. The concentration of the dissolved iron ions was lower than 0.8 mg/L. The free radicals generated in the system was characterized. Mechanistic studies showed that HO? plays a critical role in this system.