Study On Performance And Mechanism Of N/B Co-Doped Carbon-Based Catalyst Activating Persulfate To Degrade Ofloxacin

Ofloxacin（OFX）is a commonly used quinolone antibiotic that induces bacterial resistance genes and disrupts ecological balance.It has been detected to varying degrees in numerous water bodies throughout China,necessitating the development of an efficient removal method.Persulfate advanced oxidation is one of the most effective methods for removing such pollutants.The co-doping strategy has the potential to synergistically enhance the catalytic activity of carbon-based catalysts by exploiting the benefits of multiple dopants,yet there remains a dearth of relevant investigations.Therefore,in this study,N/B co-doped carbon-based persulfate catalysts were synthesized using polyaniline as a precursor.The co-doping elements of N and B with similar atomic radii but significant electronegativity differences were employed.The performance of activated peroxodisulfate（PDS）was investigated for the degradation of OFX,and the mechanism of action was clarified through catalyst characterization,performance investigation,identification of active species,contribution studies,and theoretical calculations.It enriches our comprehension of the PDS activation mechanism by N/B co-doped carbon materials,offers an efficient approach to boost the catalytic activity of carbon materials,and provides theoretical and technical support for practical wastewater treatment applications using carbon materials.The primary research contents and findings are outlined as follows:（1）A series of N/B co-doped carbon-based catalysts were synthesized through boronic acid-doped polyaniline which was used as a precursor for carbonization at different temperatures.A nitrogen-doped control material was obtained by de-doping to remove B.Various characterization techniques were employed to investigate the morphological structure,chemical composition,and properties of the prepared catalysts.XRD and Raman analyses revealed the extent and type of defects in the catalysts,while BET results indicated that higher carbonization temperatures led to a reduction in specific surface area.Additionally,it was found that the pore structure of the catalysts was predominantly mesoporous and macropores.（2）The performance of each catalyst prepared to activate PDS for the degradation of OFX was investigated.Among them,the CNB-1000/PDS system exhibited superior OFX degradation performance,achieving complete degradation of OFX within 45 min with a reaction rate constant of 0.12 min^-1,demonstrating the beneficial effects of higher carbonization temperature and B co-doping on catalytic activity.The impact of various reaction conditions on the degradation efficiency of the CNB-1000/PDS system and its potential for practical applications were also investigated.The system demonstrated a broad pH range（pH=5.00-9.00）,excellent degradation performance towards a diverse array of pollutants,and remarkable reusability with 82.90%OFX degradation after three cycles.Moreover,the analysis of the generated intermediates revealed that the system can degrade OFX through diverse pathways encompassing demethylation,decarboxylation,ring-opening of piperazine groups and dehydrogenation reactions.（3）The main active species involved in the CNB-1000/PDS system were identified as CNB-1000-PDS*and singly linear oxygen（¹O₂）through quenching experiments,EPR analysis,probe experiments,and electrochemical analysis.Competitive kinetics further determined that CNB-1000-PDS*played a dominant role with a contribution ratio of 96.18%.By comparing the changes in functional groups before and after the CNB-1000 reaction,structure-function relationship and theoretical calculations,it was determined that the sp² hybridized carbon network in the catalyst effectively facilitated electron transfer,with the BN3 structure serving as the primary active site.