Preparation Of Fe, Zn And Al - Pillared Montmorillonite And Catalytic Wet Oxidation Of Hydrogen Peroxide To Degradation Of Acid Orange Ⅱ

Montmorillonite (Mt) intercalated by polymeric metal-containing oxocations is a new class of layered compounds with abundant pore structure. After being pillared by metal ion, the Mt obtained enhanced specific surface, interlayer spacing, pore structure, surfactivity and stability for wide applications in the filed of catalysis, adsorption and environmental treatment. Aiming at the weak stability of Fe,Al-Mt used in degradation of organic wastewater, this work studied the effect of introduction of Zn into Fe, Al-Mt on the structure, activity and stability of pillared Fe,Zn,Al-Mt catalyst.The Fe,Zn,Al-Mt catalyst were synthesized by ion exchange process. The effect of different preparing conditions (such as Fe/Zn molar ratio, active metal loading and calcinated temperature) on the properties of Fe,Zn,Al-Mt catalyst was studied. Characterization studies were performed by N2-adsorption/desorption, ICP, FTIR, DR UV-Vis spectroscopy, SEM and XRD. Besides, the catalytic performance of Fe,Zn,Al-Mt was analyzed through wet peroxide oxidation of Orange Ⅱ under mild experimental condition. The results of characterization and reaction showed that the pillared-Mt in this work acquired enhanced structure after being pillared by Fe,Zn,Al-containing solution. Besides, The Fe,Zn,Al-Mt with Fe/Zn molar ratio of 3/7, active metal loading of 6% and calcinated temperature of 500 ℃ obtained increased layer distance, enhanced specific surface, microporous volume and more active site (ZnFe2O4 nanoparticles), which contributes to degradation of dye wastewater (The COD removal of Orange Ⅱ can reach to 77.1% after being treated 3 h by Fe,Zn,Al-Mt catalyst). Moreover, the result of the stability and reusability test of pillared-Mt showed that the COD removal reached to 73.2% in the fifth catalytic run and the Fe leaching content only was 0.0016 mg/L. These results indicated that the prepared Fe,Zn,Al-Mt catalysts exhibited superior stability.Further, the Fe,Zn,Al-Mt prepared under optimized conditions was used as catalyst for CWPO degradation of simulative dye wastewater (Orange Ⅱ). The kinetics of CWPO degradation of Orange Ⅱ, as well as the effect of different reaction conditions (such as reaction temperature, intial pH of Orange Ⅱ, concentration of oxidant (H2O2) and catalyst dosage) on the CWPO degradation of Orange Ⅱ with Fe,Zn,Al-Mt catalyst were investigated. The results showed that the reaction temperature and intial pH of Orange Ⅱ importantly affected the degradated efficiency of Orange Ⅱ. The chroma removal and COD removal of Orange Ⅱ can reached 100% and 77.1%, respectively, after 3 h of reaction at temperature of 60 ℃, intial pH of Orange Ⅱ of 3.0, concentration of H2O2 of 24 mmol/L and catalyst dosage of 0.5 g/L. Besides, the degradation of Orange Ⅱ by a heterogeneous catalytic wet hydrogen peroxide process was described a simple semi-empirical kinetic model, based on the Fermi equation. The result of fitting experimental data by Marquardt-Levenberg method confirmed that the reaction is a complex process with the apparent reaction order of 0.54 and apparent activation energy of 54.76 KJ/mol. Moreover, the degradated mechanism of Orange Ⅱ was investigated by in situ Raman technique and a reasonable degradation-rate of Orange Ⅱ was proposed.In the last part of this experiment, the external field energy (microwave) was introduced for preparation of Fe,Zn,Al-Mt catalyst in order to decrease the prepared time and water. The effect of different microwave time, microwave power and concentration of Mt suspension on the structure properties and catalytic performance of Fe,Zn,Al-Mt catalyst were studied. The result showed that compared with the traditional preparation method, the catalyst prepared by microwave method can save 78% time. Besides, the Fe,Zn,Al-Mt catalyst prepared by microwave method (microwave time of 10 min and microwave power of 100 W) exhibited superior activity than that of Fe,Zn,Al-Mt catalyst prepared by traditional method. Futher, under the same microwave conditions, improving the concentration of Mt suspension can save large amounts of water without affecting the properties of catalyst.