Study On Catalytic Performance And Application Of FeNi/NF Electrocatalysis System In The Treatment Of High-Salt Wastewater

High-salt wastewater with complex sources contains a lot of salt,and its conventional sewage treatment is limited by the coexistence of salt and pollutants.Electrocatalytic oxidation has unique advantages in treating high salt wastewater,which can make full use of salt ions in wastewater and improve treatment efficiency.In this study,iron-nickel bimetallic material was successfully loaded on a nickel foam（NF）sheet（FeNi/NF）by hydrothermal synthesis.FeNi/NF was characterized by SEM,EDS-mapping,XRD,and so on.The characterization results show that a large number of microspheres have been successfully loaded on the three-dimensional structure of nickel foam,with diameters ranging from 2 to 6μm.Each microsphere is assembled from thin nanosheets of different thickness.EDS mapping confirmed the uniform distribution of Fe,Ni and O elements on the electrode.XRD analysis showed that FeNi-LDH was successfully loaded on nickel foam.The characteristic peaks of various substances（such asβ-Ni（OH）₂ and Fe OOH）in Raman and FT-IR also confirmed the speculation of XRD analysis.XPS analysis further proved the valence distribution of Fe,Ni and O.Thus,the microstructure,element valence,crystal structure and other details of FeNi/NF were deeply explored,which confirmed the successful preparation of FeNi/NF.An electrocatalytic system based on the cathode（FeNi/NF）is further proposed for the removal of organic pollutants in high salt wastewater in this study.Tetracycline was selected as the target pollutant,dimensionally stable anode（DSA）and FeNi/NF were used as anode and cathode respectively to explore their catalytic performance and mechanism under different conditions.Compared with other cathode systems（carbon felt,nickel foam,copper foam,stainless steel and nickel-iron foam）,FeNi/NF electrocatalysis system shows the best tetracycline removal rate.By exploring the effects of environmental factors such as applied current,initial p H,concentration of pollutants and salinity on FeNi/NF-system,the experimental conditions were determined and its stability in extreme environment was confirmed.Combined with the free radical quenching test,free chlorine species content analysis and LSV test,the results show that reactive chlorine species（RCS）improves the speed and efficiency of electrocatalytic degradation of tetracycline.The FeNi/NF-system has the largest RCS retention capacity,so the tetracycline degradation efficiency is higher than that of other cathode systems.The RCS retention capacity of the electrocatalytic system depends on the reduction ability of the cathode to the RCS.And the hydrogen production activity of FeNi/NF is the highest,which means that hydrogen evolution reaction tends to occur and inhibits the reduction of RCS.The application potential of FeNi/NF-system in the treatment of mariculture wastewater was comprehensively evaluated,by analyzing the cycle stability,mineralization potential,performance and concentration effect of FeNi/NF-system in simulated mariculture wastewater.Although FeNi/NF has been recycled for 20 times,the tetracycline removal efficiency by the FeNi/NF-system has always remained above97%.In addition,the SEM and XPS characterization of FeNi/NF after 20 cycles also showed that FeNi/NF basically did not change,which confirmed the long-term stability of FeNi/NF and its system.Therefore,the application of high chlorine resistance electrocatalytic system provides the possibility for the practical electrocatalytic treatment of mariculture wastewater.In addition,the FeNi/NF-system was combined with iron-carbon micro-electrolysis to treat the actual high salt chopped pepper wastewater.For the high-salt organic wastewater with a salt content of 12.5%and COD of 31000～40980 mg/L,iron-carbon micro-electrolysis redox and flocculation sedimentation were used for preliminary treatment.Further,FeNi/NF-system was used for advanced treatment in order to further remove organic pollutants.The effects of Fe:C,salinity and stirring speed on COD removal were studied.The optimal parameters were determined:600rpm,Fe:C=2:1 and salinity:6.0%.On this basis,the COD treatment efficiency of FeNi/NF-system coupled iron-carbon micro-electrolysis technology is 92.01%,in the contributions of iron-carbon micro-electrolysis and FeNi/NF electrocatalysis are 3.05%and 96.95%respectively.