Study On The Typical Antibiotics Degredation In Circulation DBD Plasm Water Treatment System Coupled With Cu-CeO₂@Cellulose Acetate Films

The antibiotics in water environment have unpredictable harm to human health and the growth of aquatic organisms.Hence it is necessary to develop efficient and eco-friendly technology to alleviate the problem of antibiotic pollution in water.As one of the advanced oxidation processes,dielectric barrier discharge plasma（DBDP）has the advantages of simple operation,high efficiency and no secondary pollution,and accordingly has good application potential in wastewater treatment.However,the DBDP technology also has the problems of insufficient utilization of active substances（O₃ and H₂O₂）and physical effects（ultraviolet light）,which result in the energy loss of the system.In this study,a cyclic DBDP system based on the volume surface composite DBD（V-SDBD）was set up,and then the Cu-CeO₂@CA/DBDP coupling system was established by combing the DBDP with the Cu-CeO₂@cellulose acetate（CA）to improve the treatment efficiency of the antibiotic wastewater as well as the energy utilization efficiency of the system.In the study,the cyclic V-SDBD water treatment system was firstly established by using the V-SDBD structure and the stainless-steel metal mesh was used as the high-voltage electrode.The degradation of sulfadiazine（SDZ）and the generation of active species was reviewed to determine the optimal electrode parameters and solution circulation flow rate of the system.Secondly,the Cu-CeO₂@CA film was prepared and characterized,and the Cu-CeO₂@CA/DBDP coupling water treatment system was set up.In the synergistic system,the ciprofloxacin（CIP）was chosen as the target pollutant,and the effects of different films’addition and solution conditions on the degradation efficiency of CIP in the coupling system were investigated.Thirdly,the change of physicochemical properties of the CIP solutions during the degradation in the coupling system was examined,the generation of active substances,the influence of collectors’addition,the generation of intermediates,and the possible degradation pathways of the CIP,the mechanism of the CIP degradation in the Cu-CeO₂@CA/DBDP coupling system was comprehensively summarized.The main research results are concluded as follows:（1）A cyclic V-SDBD water treatment system was built.The electrode parameters and solution circulation flow rate of the system were optimized.The research results indicate that the 10-mesh electrode and the 333 ml L^-1circulating flow rate were the optimal operating conditions for the SDZ degradation.Under the reaction conditions,the removal rate,reaction rate constant,and energy utilization rate of SDZ were 95.5%,0.05016 min^-1,and 3.309 g k Wh^-1,respectively,which were higher than the results obtained in the other three mesh（14,20,and 40 mesh）electrode systems;The results of relative emission spectra,discharge characteristics and active species generation analysis indicate that the 10 mesh electrode system had a higher field strength during the discharge process,which could generate a large number of current pulses,and then resulted in the more O₃(0.113 mg L^-1)and H₂O₂(0.52 mg L^-1)being formation.The biodegradability of the SDZ solution after treatment were improved and the toxicity reduced.（2）The Cu-CeO₂@CA composite film was prepared and characterized,and the Cu-CeO₂@CA/DBDP coupling system was then established to treat the CIP solutions.The obtained results showed that the CIP removal in the coupling system with the 5%Cu-CeO₂@CA films addition increased from 79.2%to 89.5%（40 min）compared with the sole DBDP system.The corresponding synergic factor was 1.4.Neutral solution was conducive to the CIP degradation in the coupling system.The addition of Cu-CeO₂@CA film did not change the discharge characteristics of the DBDP system,indicating that the increase of the CIP degradation and the energy utilization efficiency in the coupling system were due to the catalytic effect of the composite film.After four cycles of use,the structure of the Cu-CeO₂@CA film was stable and it still maintained a relatively good catalytic effect.（3）The mechanism of CIP degradation show that the p H of the CIP solution gradually decreased and the conductivity gradually increased under the action of the sole DBDP.The addition of 5%Cu-CeO₂@CA film could strengthen the trend.The biodegradability of the CIP solution treated by Cu-CeO₂@CA/DBDP process was further increased.The H₂O₂concentration in the reaction system increased and,and promoted the transformation of O₃ into other reactive oxygen species（ROS）.¹O₂,·O₂ˉand·OH formed in the coupling system of played a main role to the CIP degradation,with ¹O₂ and·O₂ˉhad the biggest contribution.According to the LC-MS analysis and identification for the byproducts formed from the CIP degradation,three possible degradation pathways were speculated.The toxicity of CIP solution was reduced after the treatment.The mechanism of CIP degradation by the DBDP coupled the Cu-CeO₂@CA film were summarized as:on the one hand,the active sites on the composite film catalyze the decomposition of O₃ into various ROS;on the other hand,the composite film was excited by UV light to produce electron-hole pairs,while the Cu ions doping could inhibit the electron-hole recombination and then improved the utilization rate of the photo generated carriers,thus the photocatalytic effect of the composite film was enhanced and more ROS was generated.In conclusion,the synergistic catalysis of the Cu-CeO₂@CA composite film could promote the active substances generation in the DBDP system,thereby improve the CIP degradation.