Study On Hollow Prismatic Metal-Organic Frameworks Prussian Blue Analogue Derivatives In Activation Of Peroxymonosulfate For Organic Pollutants Degradation In Wastewater

Persulfate advanced oxidation process（SR-AOPs）is a new type of advanced oxidation process that has received a lot of attentions because of its potential for efficient degradation of refractory organics due to the higher oxidation potential of the persulfate compared to the hydrogen peroxide normally used in advanced oxidation process and the higher oxidation potential of the in situ generated sulfate radical than the hydroxyl radical.Developing efficient,stable,and easily recyclable persulfate advanced oxidation process catalysts and the investigation of persulfate activation mechanism are the current research hotspots.In this study,hollow prismatic Co-Fe Prussian blue analogue（Co-Fe PBA（Prism））was prepared by self-sacrificial template method.It was further transformed into cobalt-iron bimetallic oxides with hollow structures（Co-Fe Oxide（Hollow Prism）,CoFeO-Prism）and magnetic nitrogen-doped carbon-coated CoFe bimetallic alloys（Co₇Fe₃@C-Prism）.Both catalysts were used to activate peroxymonosulfate（PMS）in refractory organic pollutants degradation.The mechanism of activation of PMS was speculated and studied by free radical quenching and characterization.The main research contents and results are as follows:（1）By using the prismatic cobalt salt modified by cobalt（II）acetate as the template,the hollow prismatic bimetallic PBAs were synthesized by the self-sacrificial template method.The hollow prismatic PBAs were slowly heated to 250℃in air and calcined to prepare hollow prismatic bimetallic oxide derivatives.The metal oxide derivatives were characterized and analyzed for their morphology,structure,phase,element valence and thermal stability,and the catalytic performance was investigated by degradation of rhodamine B（RhB）and tetracycline hydrochloride（TC-HCl）.The analysis of experimental data shows that the CoFeO-Prism catalyst has good catalytic activity,to degrade 200 m L RhB solution of 50 ppm within 30 min,and degrade 200 m L 85%of the 50 ppm TC-HCl solution within 50 min,showing excellent performance.It showed better catalytic performance than solid cubic PBAs derivative catalysts prepared in the same way,and similar catalysts in other literatures.It also has the advantages of lower PMS consumption,higher catalytic activity,and shorter reaction time.The catalyst maintained stable catalytic performance after four cycles with good recyclability.Finally,through the free radical quenching experiment,it was found that the main active substances in the reaction after the activation of PMS by bimetallic oxides were ¹O₂ and SO₄^·-.（2）By using prismatic cobalt salts which modified from cobalt acetates as the templates,PBAs were prepared by the self-sacrificial template method and then slowly heated to 650°C and calcinated in a nitrogen atmosphere to prepare the nitrogen-doped carbon-coated Co-Fe bimetallic alloys derivative with hollow prismatic morphology（Co₇Fe₃@C-Prism）.The morphology and structure,phase,element valence,thermal stability and magnetic properties of the material were characterized and analyzed.RhB and TC-HCl were used as target degradation substances to investigate the catalytic performance.The experimental results show that the catalytic performance of bimetallic alloys derivatives is better than that of bimetallic oxide derivatives with excellent catalytic activity.It can completely degrade 200 m L 50 ppm RhB solution within 10min,and the degradation rate of 200m L 50 ppm TC-HCl solution reaches 92%within 30min.It also shows better catalytic performance than solid cubic CoFe alloys prepared by the same method,and other catalysts in literatures with shorter reaction time,less PMS dosage,and less catalyst dosage.According to the free radical quenching experiment and X-ray photoelectron spectroscopy analysis before and after the reaction,the main active substances in the system are ¹O₂ and SO₄^·-.The catalyst has strong magnetic properties and can be easily separated from the reaction system by magnet.It also maintains stable catalytic performance after four cycles,which means good recyclability and usability.