Study On The Degradation Of Dibutyl Phthalate By Iron And Cerium Bimetal Catalysts In Electro-fenton System

As a plasticizer,dibutyl phthalate（DBP）is widely used in all walks of life.As an endocrine disruptor,it is difficult to degrade common wastewater treatment process effectively,and the water pollution caused by DBP cannot be ignored.Electro-Fenton oxidation technology,as an advanced oxidation technology,has great advantages in the treatment of refractory wastewater.In this paper,a kind of high efficiency iron,cerium bimetal catalyst was used in electro-Fenton system to treat dibutyl phthalate,which has good effect.Fe-Ce/Al-MCM-41,a bimetallic catalyst modified by aluminum,was prepared by hydrothermal calcination and characterized by XRD,BET and XPS.The removal rate under different reaction conditions,such as initial p H value,catalyst dosage,current intensity and oxygen flux,was studied by single factor experiment,and the optimal operating conditions were determined.Through kinetic fitting and analysis of the degradation process,the degradation law and catalytic mechanism of organic matter in the system were explored.The stability of catalyst was tested by repeated use experiment.The specific conclusions are as follows:（1）With the method of hydrothermal synthesis,preparation of a heterogeneous bimetallic catalysts.Through single factor experiment,the catalyst prepared under the conditions of 550℃calcination temperature,6h calcination time,1:1 optimal metal ratio of ferric cerium and 0.25 wt%Aluminum ion ion doping amount is the best catalytic effect.By comparing the study found that the preparation of iron and cerium bimetallic catalyst Fe-Ce/Al-MCM-41 DBP in Fenton method processing system have good catalytic effect,and after doping of 0.25 wt%Al ions bimetallic catalyst is better than a single metal catalyst of catalytic effect.（2）The catalysts prepared by BET,TEM,XRD,FT-IR and XPS were characterized.The results showed that the catalysts prepared by hydrothermal synthesis could effectively retain the good structural properties of the mesoporous material MCM-41,with a large specific surface area and pore size,which was conducive to the surface catalytic reaction of the catalyst.Catalyst of iron and cerium,three kinds of aluminum metal ions replace the silicon atoms on the MCM-41,and load on the catalyst,this catalyst has better stability,through the experiment show that the catalyst after repeated use four times,the catalytic effect is only slightly lower.The leaching amounts of Ce and Fe were 0.27 mg/L and 0.81 mg/L respectively,high stability and repetition utilization.（3）Various factors affecting the reaction efficiency of electro-Fenton were studied in this paper.Through single factor experiment,the optimal operating conditions for the dissimilar electro-Fenton system to degrade dibutyl phthalate were as follows:Na₂SO₄was used as electrolyte,p H was 3,current strength was 0.15 A,oxygen flow was 0.2 L/min,and catalyst dosage was 0.5 g/L.Under the condition of120 min,the removal rate of DBP with initial concentration of 10 mg/L can reach97.1%,and it has a removal rate of over 92.1%at a wide p H（2～7）.（4）The removal effects of DBP by seven different processes were compared:1.Carbon felt adsorption;2.D1 adsorption;3.D4 adsorption;4.D1+carbon felt adsorption;5.D4+Carbon felt adsorption;6.Carbon felt+Electro-Chemical oxidation;7.D4+Electro-Fenton process.The DBP removal rates of these seven different processes are 52.6%,26.4%,26.9%,66.9%,60.6%,59.8%and 97.1%,respectively.The experimental results show that DBP degradation mainly involves electro-Fenton,carbon felt adsorption,catalyst adsorption,electro-Chemical reaction and other reactions.The combined effect of adsorption and electro-Fenton plays a decisive role in the removal of DBP.（5）Through the life waste water of DBP degradation research,found in actual wastewater system,the use of the experimental conditions treatment,removal rate of DBP still has certain reaction after 120 min in waste water of life itself is a small amount of DBP degradation effect of 77.7%,by adding the experiment found that the DBP concentration of 2 mg/L and 10 mg/L of actual wastewater removal rate were84.7%and 90.6%respectively.（6）The degradation mechanism of DBP in platinum-carbon felt electro-Fenton system was analyzed,and the main active substance was·OH,using carbon felt as the cathode,with adsorption of cerium iron bimetallic catalysts have synergy,catalyst Fe-Ce/Al-MCM-41 on the synergistic reaction in the process of catalytic metal ions,is advantageous to the catalytic reaction of bivalent iron ion,can improve the catalytic efficiency.In this study,the heterogeneous electro-Fenton degradation DBP system conforms to the first-order kinetic equation,and the degradation rate constant of DBP at the initial concentration of 10 mg/L is 3.44×10-4 s^-1,which is better than the ordinary Fenton process.（7）The removal rate and degradation rate of catalysts with different Al content were analyzed,and the results showed that although Al ion did not participate in the electro-Fenton reaction,the surface properties and surface structure of the prepared catalysts were also different with different Al ion content,and the doping of 0.25 wt%Al ion could improve the stability and catalytic rate of the catalysts.