| Nowadays,dye wastewater treatment has received much attention with the development of dye industry,especially the Azo dyes wastewater.Azo dye shows high toxic and colorful from the textile industry,which have resulted in serious harm to the aquatic environment,the quality of life and health.Several methods have been developed to degrade pollutants from wastewater,but they are always ineffective.Catalytic Wet hydrogen Peroxide Oxidation(CWPO)can be an effective method to degrade organic wastewater with high concentrations.The polycation exchange methodology is applied to synthesize the series of Fe/Mn/Al-pillared montmorillonite(Fe/Mn/Al-Mt).Here we investigated the effects of Fe-Mn molar ratio,active metal loading(AML),calcination temperature,preparation methods and clay suspension concentration on the efficiency of Fe/Mn/Al-Mt catalysts.Characterization technologies were performed by FT-IR,XRD,DR UV-vis,N2-adsorption/desorption,SEM,TG/DTG.Meanwhile,the catalytic performance of Fe/Mn/Al-Mt was analyzed through the efficiency of acid orange Ⅱ(AOⅡ)wastewater degradation.The catalytic wet peroxide oxidation technique is applied during reaction under mild experimental condition(degradation,COD removal and Fe leaching were used as evaluation indexes).The results show that the pillared-Mt structures characteristics are improved obviously after being pillared by using Fe/Mn/Al-containing method.When the Fe-Mn molar ratio is 8/2,the AML is 6%,the calcination time is 2 h at 500 ℃,ultrasonic treatments are applied and the dry clay is prepared directly,the Fe/Mn/Al-Mt catalysts show a large specific surface area(214 m2/g),more active sites,high catalytic activities(COD removal can reach to 81.5%),good stability(five times of repeated use of the catalyst,COD removal rate of water samples can still reach to 74.1%,total iron ion leaching are only 1.233 mg/L).In addition,the preparation period can reduce 80%and the amount of water can reduce 50 mL for 1g Fe/Mn/Al-Mt catalyst compared with the traditional preparation method.The optimized 6%-Fe/Mn/Al(8/2)-(D)Mt(U,500 ℃)catalysts are applied to degrade the acid orange Ⅱ wastewater by apply the CWPO technique,the COD removal rate and Fe ion leaching are the evaluation indexes.The technological conditions were optimized by using single-factor experiment combining with the response surface analysis,where the temperature,pH,Fe/Mn/Al-Mt quantity and H2O2 concentration are considered as influence factors.The optimal bleaching conditions can be decided on a scope by single-factor experiment.Based on the response surface analysis,we find the importance of influence factors is temperature>pH>Fe/Mn/Al-Mt dosage>H2O2 concentration.According to the results of Design-expert software package calculations,we find that the best experimental conditions should be the reaction temperature is 60 ℃,pH is 3.5,The COD removal rate can reach 83.2%and the Fe ion leaching was 0.588 mg·L’-in the theoretical predictions.Finally,the semi-empirical kinetic model—Fermi’s equation is used to describe degradation process of acid orange II with the Fe/Mn/Al-Mt heterogeneous as catalysts in CWPO.The linear relationship between InK and 1/T was obtained by fitting the acid orange Ⅱconcentration as a function of reaction time at different temperatures.The apparent activation energy was obtained according to the Arrhenius equation(Ea=48.65 KJ/mol).Compared with the previous reports,it requires smaller activation energy during the reaction process in our method.As a result,the performance of catalysts are more effective in the waste water treatment by applying the CWPO technique. |
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