Study On The Degradation Effect Of Levofloxacin By Hydrodynamic Cavitation And Its Enhanced System

In recent years,the process of industrialization has been gradually accelerated.The industrial production of pharmaceuticals and the antibiotic residues produced in the medical field have caused serious harm to water resources.Due to the great increase in the demand and usage of antibiotics,coupled with the lagging technology in the pharmaceutical field,the utilization rate of antibiotic raw materials is low,and the discharge rate of antibiotic wastewater is increasing year by year.However,a large amount of antibiotic wastewater is directly discharged into the environment without timely treatment,which not only threatens the stability of the ecological environment.It also causes human and animal health damage to long-term exposure to antibiotics in the environment.Therefore,it is urgent to develop effective treatment technology for antibiotic wastewater.Hydraulic cavitation has a good technical advantage in the field of water treatment.Moreover,it is also wide range of application in the fields of chemical industry,biological engineering,pharmaceutical synthesis and food engineering.The combined treatment of hydraulic cavitation and other technologies can greatly improve the removal rate of pollutants and increase its energy utilization rate.Therefore,this provides theoretical basis and guiding significance for further research in the future,and has broad development prospects in the field of water treatment.In this paper,the effects of inlet pressure,orifice number,circulation time,initial concentration and p H value on degradation of levofloxacin under the effect of hydraulic cavitation alone were studied.The construction of hydraulic cavitation strengthening system and its influence on degradation of levofloxacin were discussed,and the relevant exploration and analysis of H₂O₂addition level,UV lamp power,temperature and other influencing factors were discussed.Finally,the effects of different active free radicals under cavitation strengthening system were investigated by free radical scavenging experiment.The main results are as follows:（1）Under the action of hydraulic cavitation alone,the inlet pressure was 3 bar,the initial concentration of levofloxacin was 5 mg/L,the initial p H value was 3,the number of holes in the orifite plate was 4,and the cycle time was 2.5 hours.Under this condition,the degradation effect of levofloxacin was average.In order to reduce the loss of apparatus and reagent,the initial parameters were optimized to the appropriate value.The initial p H value was 6,and other initial parameters remained unchanged,and the degradation rate reached 29.3%.（2）In order to further strengthen the hydraulic cavitation effect,an experimental device of the hydraulic cavitation strengthening system was constructed,which was composed of two parts:a hydraulic cavitation circulation device and a photochemical strengthening device.When the levofloxacin solution flows through the experimental device,it is mostly degraded due to the synergistic effect of cavitation effect,ultraviolet lamp irradiation and oxidation of H₂O₂.Under the action of the hydraulic cavitation strengthening system,the addition amount of H₂O₂is 0.5 mmol/L,the temperature is 39.1℃,and the power of the UV lamp is 8 W,and the hydraulic cavitation combined UV/H₂O₂strengthening system is adopted.At this time,the degradation effect of levofloxacin is better at the hydraulic cavitation strengthening system.In order to save energy during the experiment,the initial parameters were optimized to the appropriate value,the temperature was controlled at 35℃,the power of the UV lamp was 4 W,and the degradation rate reached 80.6%.（3）The effects of superoxide free radicals and hydroxyl free radicals on levofloxacin degradation in the cavitation enhanced system were investigated by free radical scavenging experiments.When levofloxacin flows through the hydraulic cavitation strengthening device,a large number of superoxide free radicals and hydroxyl free radicals,which have strong oxidation ability,can react with levofloxacin and then decompose it.In this study,benzoquinone（BQ）were used as the scavenger of superoxide free radical（·O₂^-）and tert-butanol（TBA）as the scavenger of hydroxyl free radical（·OH）.When BQ and TBA were added,the degradation rates of levofloxacin were reduced from 80.6%to 60.2%and 19.8%,respectively,indicating that under the action of hydraulic cavitation enhancement system,Both superoxide free radicals（·O₂^-）and hydroxyl free radicals（·OH）play a role in the degradation of levofloxacin,among which hydroxyl free radicals（·OH）play a major role,followed by superoxide free radicals（·O₂^-）.