Study On The Performance Of Coal-based Activated Coke Loaded With Magnesium Ferrite Activated Persulfate To Remove Phenols From Semi-coke Wastewater

In recent years,the national standards for enterprise wastewater discharge have become more and more stringent,which makes the requirements for the treatment process of semi-coke wastewater and coal chemical wastewater higher and higher.The effluent of the original process must be treated in depth to reach the national sewage discharge standard.At present,the mainstream treatment processes are adsorption,biochemical treatment,chemical oxidation and their combination processes,which are widely used in enterprises.Advanced oxidation technology attribution and chemical oxidation method based on SO₄^-·are widely used in the field of water treatment because of its high reaction efficiency and no secondary pollution compared with other treatment methods.In this study,phenol in aqueous solution was used as a model compound,coal-based activated coke was used as a carrier,and Mg Fe₂O₄ composite metal oxide was used as a key active material to prepare a low-cost,environmentally friendly and sustainable coal-based activated coke supported magnesium ferrite（Mg Fe₂O₄/AC）composite material（MFA）for activating persulfate（PS）to stimulate free radicals to degrade refractory organic macromolecules in water.The structure,morphology and composition of MFA composites were analyzed by XRD,SEM,TEM,BET,FTIR and XPS.SEM,TEM and XRD characterization methods show that there is a uniformly dispersed spherical convex structure on the surface of MFA,and its diffraction peak is consistent with the characteristic peak of Mg Fe₂O₄.BET and pore size analysis showed that the specific surface area of the material was 397.51 m²·g^-1,and most of them were mesoporous.The characterization results of SEM-EDS and XPS showed that the MFA composites included four elements:C,O,Fe and Mg.In addition,this paper cleverly designed hysteresis loop experiment and magnet recovery MFA experiment to explore the recyclability of materials.The results show that the composites have good magnetic properties,high recovery rate and reusability.MFA was used as an activator to activate PS,and a MFA-activated PS persulfate system was constructed.By comparing the activation performance of MFA at different pyrolysis temperatures,it was found that the experimental results of the reaction system showed that when the pyrolysis temperature was 800^oC and the reaction pyrolysis time was kept at 2 h,the MFA composite material（MFA-800）activated persulfate PS system to degrade and remove phenol.The effect was significantly stronger than that of other pyrolysis temperature composites（MFA-600,MFA-700,MFA-900）activated persulfate PS system.The effects of MFA-800 dosage,PS concentration,reaction temperature and initial p H on phenol removal were investigated by single factor experiments.The results showed that when the phenol concentration was 50 mg·L^-1,the MFA dosage was 0.6 g·L^-1,the PS concentration was 1.44g·L^-1,the reaction temperature was 25^oC,and the initial p H of the solution was 5,the phenol removal effect was the best,and the removal rate could reach 92.87%.After optimizing the reaction conditions by single factor experiment,the experimental results showed that the removal rate of phenol could reach 92.87%when the phenol concentration was 50 mg·L^-1,p H=5,MFA dosage was 0.6 g·L^-1 and PS concentration was 1.44 g·L^-1.In addition,the morphology and structure of MFA-800 composite did not change significantly after repeated use for 3 times,which indicated that the material had good stability.In order to explore the mechanism of phenol removal,this paper confirmed the existence of·OH and SO₄^-·in the advanced oxidation system by combining electron spin resonance experiment and quenching experiment,and found that the dominant free radical was SO₄^-·.