Study On The Optimization And Mechanism Of Fenton For Degradation Of Fourth-generation Fluoroquinolones

With the large-scale use of third-generation fluoroquinolones,the use of fourth-generation fluoroquinolones will become the future development trend.The existing sewage treatment process cannot effectively remove the fluoroquinolones in the wastewater,but highly efficient degradation methods are essential to control the contamination of fluoroquinolones.The Fenton method can degrade most difficult-to-treat organic pollutants,and has the advantages of wide application range,strong anti-interference ability,simple operation and rapid pollutant degradation.In this study,response surface optimization method was used to optimize the operating conditions of Fenton oxidation of three fourth-generation fluoroquinolones:gatifloxacin,pazufloxacin mesylate and moxifloxacin hydrochloride(initial p H value,Fe²⁺concentration and H₂O₂concentration),obtained the best operating conditions of the three antibiotics,determined that the initial p H value has the most obvious effect on the efficiency of Fenton oxidation,and simulated the model equations between the three antibiotics Fenton oxidation efficiency and operating conditions.The intermediate products in the Fenton oxidation process of three kinds of antibiotics were determined,and seven kinds of gatifloxacin Fenton oxidation products were obtained and three degradation pathways,seven kinds of pazufloxacin Fenton mesylate oxidation products and seven kinds of Fenton oxidation products were inferred.Three possible degradation pathways,four degradation products of moxifloxacin hydrochloride and two degradation pathways.The common reactions of the three targets during Fenton oxidation are defluorination,decarboxylation,and cyclopropyl shedding.The products are simultaneously determined piperazinyl cleavage and oxazinyl cleavage were also observed.In addition,the reaction rate constants of the three antibiotics were determined through competition kinetic experiments with acetophenone.Among them,pazufloxacin mesylate has the fastest reaction with·OH.This may be because it has more CH₂RX structure and is easily attacked by·OH.At the same time,the positive charge on the carbon atom is less,resulting in·OH is highly reactive.This study provides theoretical basis and technical support for the subsequent degradation of fourth-generation fluoroquinolones.