Electrochemical Degradation Of Ceftazidime On Modified Carbon Nanotube Electrode

In recent years, the production and consumption of PPCPs become more and more and a large number of PPCPs were discharged into water environment, which affected human health and safety seriously. So it is necessary to deal with such pollutants. In this paper, the method of electrochemical catalytic was uses to degrade ceftazidime. The main research content is as follows:1. Carbon nanotubes electrodes were prepared after purifying with Smol·L-1 HNO3. Modified electrode doped with earth element Ce was obtained by electrodeposition. The characterization of unpurified electrode, purified electrode and unmodified electrode, modified electrode was analyzed by SEM、FTIR、XRD、XPS、tafel curves and cyclic voltammetry. It showed that the existing form of Ce in the modified electrode surface was CeO2. Modified electrodes have better catalytic activity.2. The ceftazidime solution was electrolyzed using CeO2/MWCNT electrode as anode. Investigation of effect of current density, electrode spacing, pH, supporting electrolyte concentration and initial concentration on the removal rate of ceftazidime was finished and was compared with the removal rate of ceftazidime on unmodified electrode. The results indicated that the removal rate of ceftazidime was almost close to 100% after 60 min electrolysis at initial 1 mg·L-1 initial concentration at current density of 3 mA·cm-2 in 1 g·L-1 Na2SO4 supporting electrolyte solution under electrode spacing of 1 cm on CeO2/MWCNT electrode, while it was 34.6% on unmodified electrode. The possible degradation path of ceftazidime was analyzed by LC-MS. Amino and carboxyl was fractured at first and then C-C keys and C-N keys were fractured and then amide was generated. Then the intermediates were degraded to organic acids and ketones. At last, the intermediate were degraded to H2O and CO2.3. It was studied the current efficiency of the two electrodes under different influencing factors and found that the higher current efficiency was obtained in the first 5 min and it decreased rapidly after 5 min. The current efficiency of CeO2/MWCNT electrode was higher than that of unmodified electrode.4. The dynamic model of the two electrodes under different influencing factors was studied. It was found that the dynamic model of CeO2/MWCNT electrode under different current density, electrode spacing, pH, supporting electrolyte concentration was secondary order reaction while unmodified electrode was zero order reaction. When the initial concentration of ceftazidime was changed, the dynamic model of unmodified electrode was still accords with zero order reaction, while the CeO2/MWCNT electrode showed the characteristics of the first order reaction.