Preparation Of Iron Nanocomposite Particle Electrodes And Their Use In A Three-dimensional Electrochemical System For The Removal Of Ciprofloxacin From Water

Antibiotics have become a novel micro-pollutant due to their high bioconcentration,widespread presence and susceptibility to infections by drug-resistant bacteria,thus attracting keen attention.The three-dimensional electrochemical method,developed from electrochemical technology,can be used for the removal of antibiotics from wastewater because of its advantages of high current efficiency,ease of management and energy conservation.In this study,a new particle electrode was prepared by using montmorillonite(MMT)doped biochar(C)as a carrier loaded with nano zero-valent iron(n ZVI),and the performance and stability of the particle electrode were explored by constructing a three-dimensional electrode reactor,and the effects of environmental factors on the performance of the system were studied to investigate the removal mechanism and degradation pathway of ciprofloxacin(CIP)in the system.Firstly,the electrochemical analysis showed that the performance of the particle electrode(MMT(5%C)/n ZVI)in the electrochemical system was superior when the doping ratio of biochar was 5%and the loading of n ZVI was 0.002 mol/g,and the particle electrode could maintain a stable state when the binder content was 15%.The characterization by SEM,XRD,and BET verified that n ZVI was uniformly loaded on the carrier and the particle electrode had a large specific surface area(84.66 m~2/g)and pore volume(0.18cm~3/g).Secondly,the effects of single factors on the three-dimensional electrode system were explored by varying the operating conditions,and the results showed that the removal efficiency of CIP was positively correlated with the amount of MMT(5%C)/n ZVI particle electrode dosing and applied voltage,and negatively correlated with the initial p H and pollutant concentration.The removal rate of CIP was as high as 97.57%when the initial p H of the solution was 3,the CIP concentration was 10 mg/L,the particle electrode dosing was 5g/L,and the applied voltage was 4 V.The comparison was performed using powdered and granular particle electrodes,and the granular showed high catalytic activity(80%>)and low iron leaching(<3 mg/L)even after four cycle repetitions.Finally,the reaction kinetics,reaction mechanism and degradation pathways of MMT(5%C)/n ZVI electrocatalytic oxidative degradation of CIP in a three-dimensional electrode system were investigated.n ZVI reduction and electrochemical generation of reactive substances(e.g.·OH)and their synergistic effects were the main pathways for pollutant removal.the degradation pathways of CIP included defluorination and decarboxylation and damage of the piperazine ring,which eventually produced low molecular weight organics.