Degradation Of Phenol Of High Concentration By FeAlO_x/MMT Catalyzed Fenton Reactions

In this work, Fe/Al complex oxide supported on montmorillonite (FeAlOx/MMT) was applied in the heterogeneous catalyzed Fenton reaction for the degradation of phenol solutions of high concentration. The experimental results show that the prepared FeAlOx/MMT catalysts with the Fe/Al molar ratio of 1/5 are highly effective for the Fenton reaction, and the Fe/Al complex oxide is confirmed to be supported outside the layer structure of montmorillonite. Under lower reaction temperatures and higher pH values an induction period can be observed during which ferric ions are gradually released into the solution from the surface of FeAlOx/MMT catalysts. Consequently, the Fenton reaction in the solution is catalyzed by the released ferric ions. On the basis of reaction kinetics data, it is found that the initial concentration of H2O2, pH value of the solution and the reaction temperature have an overwhelming effect on the degradation efficiency of COD of phenol solutions. An oxidation model was established based on the detailed mechanism of Fenton reaction. Parameter estimation suggestes that the oxidation kinetics is 2 orders with respect to the COD of the solution and the activation energy is 72.8 kJ/mol. The unnecessary self-consuming of hydroxyl radicals due to the coupling between the high reaction temperature and high concentration of H2O2 can be partially controlled by applying temperature gradient and batch-wise addition of H2O2. Under the optimized reaction condition, phenol in the waste water with the phenol concentration of 1 g/L can be completely removed, with a high degradation rate of COD of 97% obtained.