Preparation Of Composite Nanometer Heterogeneous Catalyst And Its Performance In Refractory Organic Wastewater Degradation

Refractory organic wastewater usually contains a variety of high-concentration organic compounds,and the biodegradability is poor or even biotoxic.In particular,in the printing and dyeing industry,the refractory dyes wastewater have become pollution sources due to their durable color and difficult biodegradation.With the enhancement of people's environmental awareness and the stricter supervision of national pollutant discharge standards,the effective treatment of this kind of wastewater has become a hot research topic recently.Therefore,it is of certain practical significance to seek an efficient treatment process,kinds of catalysts with good reuse performance,high catalytic efficiency and economic performance,so as to meet the demand for the utilization of refractory organic wastewater treatment.Using natural attapulgite as raw material,this paper successfully supported a variety of metal oxides to obtain a composite nanometer heterogeneous catalyst,and tested and characterized the structure and microstructure of the catalyst and its support.The optimal catalysts were used to study the degradation of single dye wastewater containing methylene blue and ternary mixed dye wastewater,and the catalytic degradation process was optimized.By comparing the process of degradation of organic pollutants in wastewater by different heterogeneous Fenton reaction systems,the degradation mechanism of this process was discussed in order to have a clearer understanding of the reaction pathway.A series of heterogeneous catalysts,including Ce-Fe/ATP?SA1?,Cu-Fe/ATP?SA2?and Ce-Cu-Fe/ATP?SA3?,were prepared by ultrasonic impregnation on the surface of cheap and readily available attapulgite.Filtered through the catalyst found that when the catalyst promoter?load iron as main catalyst and other load objects are additives?precursors in the catalyst precursors and the proportion of 20%,the catalyst?SA1-4and SA2-4?and when the ratio of the amount of catalyst precursors of 1:1 the catalyst?SA3-2?in the same series catalyst showed the best catalytic performance.Ce-Fe/ATP,Cu-Fe/ATP and Ce-Cu-Fe/ATP heterogeneous catalyst characterization results show that the load on the surface of attapulgite was divided into cerium,copper,iron oxide,and a variety of active component of load makes the attapulgite crystal stick each other from a porous structure,effectively increase the specific surface area and the entrance of the catalyst,catalyst preparation process did not cause the concave-convex rod ishihara some crystal structure damage.The heterogeneous catalysts Ce-Fe/ATP,Cu-Fe/ATP and Ce-Cu-Fe/ATP were used to study the degradation of single dye wastewater containing methylene blue and ternary dye wastewater containing methylene blue,fused red and malachite green.A series of single-factor degradation experiments were conducted to study the effects of initial pH value,amount of H₂O₂,amount of catalyst,initial concentration of dye wastewater and temperature changes on catalytic degradation of dye wastewater in the heterogeneous Fenton reaction systems of Ce-Fe/ATP/H₂O₂,Cu-Fe/ATP/H₂O₂ and Ce-Cu-Fe/ATP/H₂O₂.The results show that under the optimal conditionsthe three kinds of heterogeneous catalyst for dye wastewater degradation after 60 min,the degradation of methylene blue dye wastewater is up to more than 99%,mixed dye wastewater degradation rate of above 90%,shows that three types of heterogeneous catalyst for mixed dye wastewater degradation rate is always lower than the same?MB?dye degradation rate.Moreover,the three heterogeneous catalysts had no significant change in the degradation rate of dye wastewater after being used for three times.The degradation mechanism of mixed dye wastewater by Ce-Fe/ATP/H₂O₂,Cu-Fe/ATP/H₂O₂ and Ce-Cu-Fe/ATP/H₂O₂ in heterogeneous Fenton reaction system was studied.The results showed that the degradation process of the mixed dye wastewater was due to the Fenton reaction,which was mainly based on electron exchange and the oxidation of strong oxidizing·OH,thus effectively removing the refractory organic compounds,and the degradation rate was positively correlated with the concentration of·OH radicals generated in the reaction.By comparison,it was found that Ce-Cu-Fe/ATP heterogeneous catalyst had the best catalytic performance,and the kinetics of its degradation of mixed dye wastewater showed that the reaction system had a low activation energy of only 4.484kJ/mol,and the active components in the heterogeneous catalyst mainly participated in the reaction in the form of oxidation state.