Preparation Of The Electrode Modified With Nickel Foam For Electrochemical Degradation Of Nitrofurazone

Antibiotics discharged into the environments?e.g.,soil and aquatic ecosystems?could increase antibiotic resistance of ecosystems,and bring about potential threats to aquatic life and even human health.Nitrofuranzone?NFZ?as a low-cost and high-efficiency broad spectrum antimicrobial agents of nitrofurans is widely used for the treatment of gastrointestinal and dermatological infections in animal husbandry and aquaculture.However,the overuse and misuse of them have led to adverse environmental effects and antibiotics resistance transfer to human pathogenic microbes.Because of the microbial resistance of antibiotics,it is very difficult to efficiently remove them using conventional methods?e.g.,activated sludge?in wastewater treatment plants.As a result,the water containing nitrofuran antibiotics is discharged frequently into the environments.Thus,wastewater containing antibiotics contaminants must be decontaminated before it is discharged into the environment.Electrochemical method has been regarded as one of the most effective technologies due to its environmental-friendly and high-efficiency properties,and electrode plays an important role for electroreductive reactions.So,this study paid more attention to simple and efficient electrodes.?1?A reduced graphene modified nickel foam electrode?GR-Ni foam?was facilely prepared via one-step cyclic voltammetry electrodeposition of graphene oxide suspension onto Ni foam,and the electrochemical degradation of nitrofurazone?NFZ,a kind of typical antibiotics?was studied on GR-Ni foam cathode.The cyclic voltammetry and electrochemical impedance spectra analysis confirmed that loading GR accelerated the electron transfer from the cathode surface to NFZ.With the applied cathode potential of-1.25 V?vs.Ag/AgCl?,the removal efficiency of NFZ(C₀=20 mg dm^-3)at GR-Ni foam electrode reached up to 99%within 30 min,showing a higher reaction rate constant(0.1297 min^-1)than 0.0186 min^-1 at Ni foam electrode.Meanwhile,the pH,dissolved oxygen and NFZ initial concentration had slight effect on NFZ degradation at GR-Ni foam electrode.The reactions first occurred at nitro groups?-NO₂?,unsaturated C=N bonds and N-N bonds to generate furan ring-containing products,and then these products were transformed into linear diamine products.The direct reduction by electrons was mainly responsible for NFZ reduction at GR-Ni foam electrode.Significantly,after 18 cycles,the removal efficiency of NFZ still reached up to 98%within 1 h.In addition,the cathodic degradation process could eliminate the antibacterial activity of NFZ.?2?The Pd-loading Ni foam was prepared through one-step electrodeposition,With the applied cathode potential of-1.25 V?vs.Ag/AgCl?,the removal efficiency of NFZ(C₀=20 mg dm^-3)on Pd-Ni foam electrode reached up to 99%.The degradation rate markedly increased with cathode potential from-0.35 to-1.25 V?vs.Ag/AgCl?,and electrochemical method is suitable to degrade NFZ with different initial concentration.Compare to the GR-Ni foam,the degradation products and the transformation pathway are the same,and the cathodic degradation process could eliminate the antibacterial activity of NFZ.But the furan ring-containing transformation products were more easily reduced to linear products by the Pd-Ni foam electrode,and the indirect electron transfer reduction played a crucial role in NFZ reduction on the Pd-Ni foam.