| Chlorinated organic compounds are a class of compounds with a wide range of pollution,high toxicity and not easy to degrade.Most chlorinated organic substances have low water solubility.Once they enter the water ecological environment,the probability of natural degradation in a short time is very small,and they accumulate in the organism through the biological chain,which will cause serious environmental pollution and long-term pollution.The consequences of ecological damage.The current methods cannot easily and quickly remove chlorinated organics,and it is imminent to develop effective methods.The traditional homogeneous Fenton method requires a strong acid environment,excessive iron salt,and the catalyst cannot be recovered and will produce iron salt precipitation,so its application is greatly restricted.At present,the popular nano-zero-valent iron?n ZVI?catalyzes hydrogen peroxide to form a Fenton-like system for wastewater treatment,but from the homogeneous iron-based Fenton reaction to the heterogeneous iron-based Fenton reaction,although the problem of catalyst recovery cannot be solved.However,strict acidic conditions to prevent iron precipitation are still the bottleneck of iron-based Fenton.Therefore,due to the limitations of the above reasons,it is necessary to modify the nano-zero-valent iron to adapt it to other reaction environments,improve the catalytic efficiency of hydrogen peroxide,and increase the removal rate of pollutants.Based on the above reasons,this study focuses on the preparation and characterization of n ZVI modified catalytic hydrogen peroxide and its modified materials,and used it to treat chlorinated organic wastewater.In this study,n ZVI and n ZVI/Cu materials were prepared by KBH4liquid phase reduction method,and then Si O2-n ZVI and Si O2-?n ZVI/Cu?were prepared by St?ber hydrolysis method.It can be seen from the TEM electron micrographs of Si O2-n ZVI and Si O2-?n ZVI/Cu?that it has been formed with n ZVI and n ZVI/Cu as the core,the outer layer is evenly coated with a transparent Si O2film,and it prevents the reunion and easy Oxidation causes uneven dispersion.Through Fourier infrared spectroscopy analysis,the infrared spectrum of Si O2-n ZVI material contains characteristic absorption peaks of O-H and Si O2,and the modified n ZVI has good oxidation resistance.In the infrared spectrum of Si O2-?n ZVI/Cu?material,it contains characteristic absorption peaks of O-H and Si O2,and the formation of Si-O-Cu bond,indicating that Cu has been successfully embedded.In the XRD analysis of both Si O2-n ZVI material and Si O2-?n ZVI/Cu?,there is a characteristic diffraction peak of elemental iron,a diffraction peak of Si O2,and none of the crystal plane diffraction peaks of iron oxide and copper oxide were found,indicating that the samples were not oxidized.,and a characteristic diffraction peak of elemental copper in Si O2-?n ZVI/Cu?.The Hc value of Si O2-?n ZVI/Cu?material tends to zero,and the particles show paramagnetism,indicating that the modification of copper metal and the coating of Si O2have little effect on the magnetic properties of n ZVI.Taking 2,4-dichlorophenol?2,4-DCP?as the degraded organic matter,the volume ratio of isopropanol/H2O,the dosage of Na OH,the dosage of TEOS and the hydrolysis time were discussed for the synthesis of materials in the system.Affect the situation,and when determining the volume ratio of isopropanol/H2O,the dosage of Na OH,the dosage of TEOS and the hydrolysis time are set to 2:1,8m L,1.5m L and 90min as the best system physical and chemical conditions.However,the comparative analysis of the removal effects of 2,4-DCP by the three materials of n ZVI,Si O2-n ZVI and Si O2-?n ZVI/Cu?found that the removal rate of Si O2-?n ZVI/Cu?was the highest,indicating that Si O2-?n ZVI/Cu?has the best reduction and removal effect on 2,4-DCP,but only about 50%,and it does not achieve a high removal rate.Therefore,we will discuss the removal of 2,4-DCP when Si O2-?n ZVI/Cu?is used as a catalyst to catalyze hydrogen peroxide?H2O2?.Using 2,4-DCP as the degradable organic matter,the effects of iron-copper doping ratio,Si O2-?n ZVI/Cu?dosage,H2O2dosage and initial p H on the Fenton-like reaction in the system were investigated to determine when the iron The copper doping ratio,Si O2-?n ZVI/Cu?dosage,H2O2dosage and initial p H were set to 2:6,0.25g·L-1,79.76mmol·L-1and 7 respectively as the best system physical and chemical conditions.And compare the cyclic degradation ability of Si O2-n ZVI,Si O2-?n ZVI/Cu?two-phase composite catalytic hydrogen peroxide to degrade 2,4-DCP.A series of kinetic experiments were carried out on the Si O2-?n ZVI/Cu?multiphase catalytic hydrogen peroxide degradation of 2,4-DCP,the kinetic factors were explored,and the kinetic equations were obtained,looking for the kinetics of Si O2-?n ZVI/Cu?multiphase catalysis hydrogen peroxide degradation of 2,4-DCP and analysis of its mechanism.Comparing the pseudo-first-order kinetic equations of n ZVI and Si O2-?n ZVI/Cu?materials,it is found that the pseudo-first-order rate constant of Si O2-?n ZVI/Cu?materials is larger,which is more suitable for the reduction degradation of 2,4-DCP.From the comparative analysis of the results of adding excessive amounts of n-butanol and KI,it can be concluded that the·OH produced at the interface of the complex phase is the main driving force for the degradation of2,4-DCP.In the process of Si O2-?n ZVI/Cu?multiphase catalytic hydrogen peroxide degradation of 2,4-DCP,iron-copper metal produces a synergistic effect,through the reaction of Fe3+and Cu+to promote the production of more Fe2+and Cu2+,in order to produces more·OH,increases the conversion of 2,4-DCP,and improves the degradation rate of 2,4-DCP. |
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