Study On Degradation Of Ciprofloxacin In Water By Graphene Oxide Matrix Composites

Ciprofloxacin（CIP）,a third-generation quinolone antibiotic,is widely used in the treatment of various bacterial infections.The mass production and use of CIP will cause a large amount of residue in water,which will affect the safety of ecological environment.CIP has typical characteristics of difficult biodegradation,which is difficult to be removed by the traditional biochemical water treatment process.Therefore,advanced oxidation technology is often used for pretreatment or advanced treatment of CIP wastewater.In this paper,heterogeneous catalytic activation monopersulfate was used to treat CIP containing wastewater,and good treatment results were obtained.In this paper,graphene oxide（GO）was prepared by improved Hummers method.Magnetic graphene oxide（MGO）and magnetic graphene oxide aluminum oxide（MGO-Al₂O₃）composites were prepared by ultrasonic assisted chemical coprecipitation with GO as carrier.The performance and related reaction mechanism of MGO and MGO-Al₂O₃composites adsorbing and activating PMS to degrade CIP were systematically studied,and the recycling performance of the composites was explored.The main research results are summarized as follows:（1）GO was successfully prepared by improved Hummers method,and GO had good adsorption on CIP.When the dosage of GO was 2.0 g/L,CIP with an initial concentration of 20 mg/L was almost completely removed after 120 min adsorption.However,it is difficult to separate GO from the solution,which is easy to cause secondary pollution while wasting materials.（2）MGO composites were successfully prepared after nano Fe₃O₄particles were loaded into GO.MGO composite has good adsorption performance for CIP,and the adsorption reaction reaches equilibrium after 480 min.When the dosage of MGO is 1.0g/L and the adsorption reaction is 480 min,the removal rate of CIP can reach 95.0%.At the same time,the adsorption of CIP by MGO conforms to the pseudo second-order kinetic model,and the isothermal adsorption process conforms to the Langmuir model.The adsorption thermodynamics shows that the reaction is a spontaneous endothermic reaction.The degradation of CIP by MGO/PMS system was studied,and the synergistic activation of PMS by Fe₃O₄and go was proved.Comparing the CIP adsorption by MGO alone with the CIP degradation by MGO/PMS system,under the same experimental conditions,when the dosage of MGO is 1.0 g/L and the time is 60min,the CIP removal rate of the former is 59.5%,and the CIP degradation rate of the latter is 87.6%.MGO can activate PMS efficiently.The experimental results show that the dosage of MGO,the dosage of PMS and the p H value of the solution affect the removal of CIP.When p H value is 7,MGO dosage is 2.0 g/L and PMS dosage is 2.0g/L,the highest removal rates of CIP and TOC can reach 96.5%and 63.4%respectively.（3）MGO-Al₂O₃composites were successfully prepared after nano Al₂O₃and Fe₃O₄particles were successfully loaded into GO.Compared with GO and MGO,MGO-Al₂O₃has larger specific surface area and more active sites.The experimental results show that MGO-Al₂O₃has good adsorption performance for CIP,and the adsorption reaction reaches equilibrium after 480 min.When MGO-Al₂O₃is 1.0 g/L and 480 min,the removal rate of CIP can reach 93.0%.The results show that the adsorption of CIP by MGO-Al₂O₃is a spontaneous endothermic reaction,which conforms to the pseudo second-order kinetic model,and the isothermal adsorption process conforms to the Langmuir model.The degradation of CIP by MGO-Al₂O₃/PMS system was studied.Under the same experimental conditions,when the dosage of MGO-Al₂O₃is 1.0 g/L and the time is 10 min,the CIP removal rate of the former is29.3%and the CIP degradation rate of the latter is 88.1%.MGO-Al₂O₃can activate PMS efficiently.In the process of catalytic activation PMS degradation of CIP,MGO-Al₂O₃dosage,PMS dosage and solution p H have a great influence on the degradation rate.When the p H value is 7,the dosage of MGO-Al₂O₃is 2.0 g/L and the dosage of PMS is 2.0 g/L,the removal rates of CIP and TOC can reach 99.2%and65.5%respectively after 180 minutes of reaction.Compared with MGO/PMS system,MGO-Al₂O₃/PMS system has better removal effect on CIP.（4）MGO and MGO-Al₂O₃/PMS composites can be regenerated by dilute hydrochloric acid and deionized water.As adsorbent and catalyst,they have good recycling performance,and the stability of MGO-Al₂O₃is slightly better than MGO.