| Aiming at the problems of widespread use of chloramphenicol antibiotics,great harm,and limited effects of existing treatment methods,based on the basic principles of electrochemical reduction reaction,new cathode materials were developed to explore the efficiency and mechanism of electroreduction treatment of chloramphenicol wastewater.The new cathode material is based on the experimentally prepared porous nano Co3O4 electrode,which is metal electrodeposited with Cu,Fe,and Pd,respectively.The optimal modification conditions are as follows: the electroplating current is 5m A / cm2,the electroplating time is 1min,the copper electrode has the best reduction effect,the removal rate of 1.5h is 99.6%;the electroplating current is 20 m A / cm2,and the electroplating time is 10 min,iron plating The electrode has the best reduction effect,and the removal rate reaches 96.41% in 1h;when the plating current is 20 m A / cm2 and the plating time is 5min,the palladium plating electrode has the best reduction effect,and the removal rate in 2h reaches 97.02%.Take the best electrode and characterize the electrode by SEM,EDS,XRD,Raman spectroscopy,cyclic voltammetry,and AC impedance method.The results show that the electrodeposited product of the copperplated electrode is(Cu0.30Co0.70)Co2O4,the grain size is 132 A°,the microscopic strain?stress?is-0.44%,the electrode thickness is relatively uniform,the electrode surface is rough,and cracks appear.The electrodeposited product of the iron-plated electrode is Fe3O4,the grain size is 236 A°,the microscopic strain?stress?is-0.16%,the electrode thickness is relatively uniform,and the surface is rough.The Fe3O4 produced by electroplating was observed at 8000 times to show a dense needle-like grid structure?orderly porous matsutake-like morphology?.The electrodeposition product of the palladium-plated electrode is elemental Pd,the grain size is 845 A°,the microscopic strain?stress?is 0.36%,the electrode thickness is uneven,the surface is rough,and metal palladium particles are attached to the electrode surface.The metal palladium particles are spherical with a minimum diameter of about 7 ?m.The palladium particles are stacked on top of each other to form a cluster structure.The length of the cluster structure observed by SEM can reach 80 ?m.Compared with the common metal electrode,DSA electrode and graphite electrode,the modified electrode has better reduction efficiency.When the current density was changed,it was found that when the current density was 10 m A / cm2,the reduction effect was the best.The removal rate of palladium-plated electrode reaction was 1.5h up to 99.62%,the reaction rate of copper-plated electrode reaction was 1.5h up to 99.96%,and the removal rate of iron plated electrode was 1h 96.97%.When the current density is 5m A / cm2,the comprehensive index of energy consumption is the best,which is the recommended current density.The electroreduction process of chloramphenicol conforms to the first-order reaction kinetics.The reaction products include: nitro reduction,carbonyl reduction,dechlorination,benzene ring hydrogenation,and intramolecular dehydration.A total of 12 products are produced: Nitro compounds,hydroxylamine compounds,AMCl2,carbonyl-reduced AMCl2,AMCl,carbonyl-reduced AMCl,AM,carbonyl-reduced AM,carbonyl-reduced AMCl2 benzene ring hydrogenation,carbonyl-reduced AMCl benzene ring hydrogenation,carbonyl-reduced The AM benzene ring is hydrogenated,and the carbonyl groupreduced AM benzene ring is hydrogenated and then dehydrated.The reaction products were used to analyze the effect of different electrode materials on the reduction mechanism of chloramphenicol: Co3O4 materials have a catalytic effect on nitro reduction and intramolecular dehydration,and metal or metal oxides modified on the electrode surface promote the dechlorination reaction. |
PDF Full Text Request