γ-MnO_2的制备及其降解苯酚的动力学研究

Study on the Preparation of γ-MnO_2 and Its Kinetics of Phenol Degradation

用水热法制备出γ-MnO2,研究其对苯酚的降解过程.用X射线衍射仪(XRD)和比表面积及孔径分布仪(BET)对γ-MnO2结构和比表面积进行测定.实验结果表明γ-MnO2能够有效地降解苯酚,同时γ-MnO2被还原为Mn2+.pH值、苯酚的初始浓度和γ-MnO2的投加量是影响降解苯酚的主要因素,对降解动力学速率有显著影响,研究反应最初20 min的反应速率,pH值、苯酚初始浓度和γ-MnO2投加量对应的反应级数分别为-3.187 3、-0.423 5和0.173 4.降解热力学研究表明,反应活化能为5.301 kJ/mol,指前因子为4.98mM4.44·min-1.为更好地理解MnO2降解水中有机污染物基本原理提供了大量的有用信息.

γ - MnO2 was prepared with hydrothemal method to study the oxidative degradation of phenol at the interface of manganese oxides and water. The crystal structure and the specific surface area of γ - MnO2 were examined by X - ray diffraction（XRD）and Brunauer - Emmett - Teller（BET）methods. The experimental re-sult showed that γ - MnO2 could effectively degrade phenol. And in the meantime,it was found that γ - MnO2 could be reduced to Mn2 ＋ . The initial 20 min kinetic reaction rate,pH value,initial phenol concentration and γ -MnO2 dosage were the main factors of influencing phenol degradation,and their reaction orders were respectively- 3. 187 3、- 0. 423 5 and 0. 173 4,respectively. The thermodynamics of phenol degradation by γ - MnO2 was also investigated,and the apparent activation energyexponential factor were estimated to be 5. 301 kJ/ mol and 4. 98 mM4. 44 ·min - 1 . This investigation will give some new insights for understanding the interaction of organic pollutants with manganese oxides.