Preparation Of Zeolite Loaded Cobalt Ferrite And Study On Its Activated Persulfate Degradation Of Eriochrome Black T

Azo dye wastewater has the characteristics of difficult degradation,high chroma and strong toxicity,and the deterioration of water resources caused by it has attracted worldwide attention.The persulfate advanced oxidation technology is widely used to treat various refractory organics,and the exploration of efficient catalysts is the focus of research.In this study,the azo dye eriochrome black T was selected as the target pollutant and cobalt ferrite-zeolite（Co Fe₂O₄-zeolite）composite was prepared.The latter was used to activate persulfate（PMS）to degrade eriochrome black T.The results obtained are as follows:（1）Co Fe₂O₄was successfully prepared by solvothermal method,and different solvothermal preparation conditions were adjusted.The results showed that the optimal preparation conditions were 50 m L ethylene glycol as solvent,and the dosage of sodium acetate was 2.46 g.The composite standard pattern of Co Fe₂O₄crystal structure was prepared,with a crystal size of 10.647 nm.74.0%eriochrome black T could be degraded by activated PMS reaction for 30 minutes.In order to further improve the catalytic performance,different mass ratios of Co Fe₂O₄-zeolite composite materials were synthesized by solvothermal method under the optimal preparation conditions.The composite material with a mass ratio of 1:1 had the best catalytic effect and could degrade 90.0%eriochrome black T in 30 minutes.Using scanning electron microscopy,energy dispersive spectroscopy,X-ray diffraction,Fourier transform infrared spectroscopy,and hysteresis loop characterization,the results showed that the crystal structure of Co Fe₂O₄:zeolite-1:1 was stable,and granular Co Fe₂O₄was uniformly loaded on the surface of cubic zeolite.Co Fe₂O₄:zeolite-1:1 contained functional groups of Co Fe₂O₄and zeolite,and could be recycled through magnets.（2）The influencing factors and optimal process conditions for the degradation of eriochrome black T in the Co Fe₂O₄:zeolite-1:1/PMS system were investigated.The results showed that the optimal degradation rate of eriochrome black T was 90.0%when the dosage of Co Fe₂O₄:zeolite-1:1 was 0.20 g/L,the dosage of PMS was 0.15 g/L,the initial p H was 5.8,the mass concentration of eriochrome black T was 200 mg/L,and the reaction temperature was 25℃.At a concentration of 1 mmol/L to 10 mmol/L,inorganic anions such as CI^-,NO₃^-and HCO₃^-had inhibitory effects on the system,with CI^-and NO₃^-having weaker inhibitory effects and HCO₃^-having stronger inhibitory effects.High concentrations of humic acid（50mg/L～150 mg/L）significantly inhibited the degradation of eriochrome black T.Experiments on the degradation of different dyes had shown that the system had the applicability for the degradation of different dye wastewater.（3）The quenching test showed that there were free radical(·OH andSO₄^?-)and non-free radical(¹O₂andO₂^?-)pathways in the Co Fe₂O₄:zeolite 1:1/PMS system,and the free radical pathway was dominant.The electron paramagnetic resonance test further showed that the system produced a large amount of·OH andSO₄^?-in a short time,and various active substances could effectively destroy the chemical structure of eriochrome black T.X-ray photoelectron spectroscopy analysis showed that in Fe（II）/Fe（III）,Co（II）/Co（III）on the surface of the composite material,there were valence state cycles which provided electrons forSO₄^?-generation by PMS.The·OH andSO₄^?-in the system was generated by further decomposition;The reduction of lattice oxygen and the surface hydroxyl groups provided by zeolite for the composite material contributed to the production of ¹O₂andO₂^?-.