Study On The Removal Of Antibiotics By Persulfate Activated By Metal Phosphide-supported Carbo

With the rapid development of industrialization,water pollution has become a serious environmental problem.Antibiotics are the main organic pollutants in wastewater due to their hard-to-biodegrade nature.Advanced oxidation processes（AOPs）are seen as an effective way to solve these pollutants because of their highly oxidizing reactive oxygen species that can efficiently degrade them,among them,persulfate activation is of interest because of its ease of operation and gentle reaction conditions.At present,the metal-based catalysts have high activation efficiency for activating persulfate but easy deactivation of active sites as well as poor structural stability,while the non-metallic carbon-based catalysts are green and stable but have low activation efficiency.Considering these,in this work,metal phosphide is combined with carbon material to prepare carbon-encapsulated metal phosphide catalyst,where metal phosphide is used as the main active sites and carbon material provides stability to achieve efficient removal of antibiotic pollutants,mainly as follows:（1）N,P-doped carbon encapsulated Fe₂P nanoparticles（Fe/P-NPGC）were prepared by a one-pot reduction method for constructing the organic wastewater purification system of Fe/P-NPGC/PMS.Through optimization of process parameters,the Fe/P1-NPGC/PMS system could finally remove 91.8%of tetracycline hydrochloride（TCH）.The initial p H,inorganic anions,and water matrixes had insignificant effects on the removal of TCH,showing a high ability to resist environmental disturbance.Based on the quenching experiments and characterization,it was found that Fe₂P activates peroxymonsulfate to generate reactive oxygen species,but also promotes the regeneration of Fe（II）,thus improving the activation efficiency of PMS and generating an efficient non-radical pathway dominated by singlet oxygen.Finally,according to the identified intermediates,the degradation pathway of TCH was proposed.（2）N,P-doped carbon nanotube encapsulated Co₂P catalysts were successfully synthesized by a strategy of simultaneous phosphorylation and carbonization using phytate as a phosphorus source.The characterizations showed that the phytic acid results in more structural defects and increases the specific surface area of the material,which contributes to persulfate activation.The Co/P-CNTs-0.3/PMS system had optimal performance with the removal rate of 97%of norfloxacin（NOR）within 60 minutes.The system had good anti-interference ability and environmental adaptability,and could degrade many kinds of pollutants.Electron paramagnetic resonance tests,quenching experiments,chemical probe experiments and reaction kinetics were combined to investigate the contribution ratio of reactive oxygen species and the steady-state concentration of free radicals in the system.The results indicated that Co₂P activated PMS to produce more SO₄^·–,the coexisting H₂PO₄^–promoted the generation of free radicals.Finally,we proposed NOR degradation pathways by product analysis and evaluated the ecotoxicity of intermediates.