Preparation Of Modified α - Fe 2 O 3 Sub - 3 And Its Degradation Of Aromatic Hydrocarbons

The high concentration, complicated composition and refractory of industrial organic wastewater make it to be a hard nut in environmental management. In this study,2,4-dichlorophenol and malachite green was selected as the model pollutants to explore the degrading performance of an improved a-Fe2O3/H2O2system which catalyzed Fenton-like reactions.The degradation of2,4-dichlorophenol using modified a-Fe2O3/H2O2Fenton-like system was investigated in detail. The effects of the dose of modified a-Fe2O3and H2O2, the initial pH, the reaction temperature and the reaction time were compared to determine the optimum reaction conditions. Under the same conditions, the COD removal rates of different strategies were ordered as:modified a-Fe2O3/H2O2> Fe2+/H2O2> Fe3+/H2O2> commercially available a-Fe2O3(activated at600℃/H2O2> commercially available a-Fe2O3/H2O2> H2O2> modified a-Fe2O3. Under the optimum conditions, the COD removal rate of2,4-dichlorophenol treated with the modified a-Fe2O3/H2O2system reached90.54%. HPLC analysis showed that about90%of2,4-dichlorophenol molecular structure was destroyed. After the treatment of this oxidative system, the BOD5/COD value of2,4-dichlorophenol simulated water sample increased from0.08to0.42, which greatly improved its biodegradability. GC-MS analysis of the2,4-dichlorophenol degrading process showed that the intermediates were p-benzoquinone,2-chloro-1,4-benzenediol and oxalic acid. A possible degradation mechanism of2,4-dichlorophenol was then proposed.On the decoloration of malachite green catalyzed by Fenton-like reaction, the effects of the dose of modified a-Fe2O3and H2O2, the initial pH, and the reaction temperature were studied and the modified a-Fe2O3/H2O2was found to be the best reaction system. The decoloration rates of different systems are ordered as:modified a-Fe2O3/H2O2> Fe2+/H2O2> Fe3+/H2O2> H2O2> a-Fe2O3(activated at600℃)/H2O2> modified a-Fe2O3> a-Fe2O3/H2O2. Under the optimum conditions, the decoloration rates of malachite green by improved a-Fe2O3/H2O2reached100%. In addition, UV-vis spectrum showed that the chromophoric group of malachite green was destructed during the degradation process and oxidized to small-molecular products. The BOD5and COD analysis of malachite green before and after degradation showed that the value of BOD5/COD increased from0.19to0.48, indicating that the biodegradability of malachite green was greatly improved. GC-MS analysis of the malachite green degradation process showed that the intermediates were glutaraldehyde, benzophenone, benzoic acid, dimethylamine and acetate. Thus, the degradation mechanism of malachite green was also proposed.