Degradation Of RB5 And Phenol By Persulfate Activated By Core-shell Carbon-based Zero-valent Iron Materials

With the rapid development of society and economy,the water pollution problem has become increasingly prominent.Most of the industrial wastewater has complex components,high concentration,poor biodegradability,and toxicity.Due to the existence of these characteristics in refractory organic wastewater,the traditional wastewater treatment technology effluent using simple physical and chemical plus biological treatment methods is widely used.It is difficult to stably meet the discharge standard,so it is an imminent problem to find efficient,energy-saving,green and reasonable means to treat refractory organic wastewater.The advanced oxidation technology of persulfate（PS）activated by heterogeneous materials is recognized as a good solution for the treatment of wastewater containing toxic and refractory organic pollutants.Carbon-supported transition metal composite materials can improve the effect of activating persulfate.Among the raw materials for preparing composite catalyst materials,transition metal or transition metal compounds have the properties of low cost,good operation,and easy availability,and are used as persulfate activation materials.,Carbon materials have the advantages of high stability,acid and alkali resistance,and abundant surface functional groups.Nitrogen and boron,as elements adjacent to carbon in the periodic table,have the atomic radius closest to the carbon atomic radius,so they become doped carbon materials.of choice.As a type of carbon material,carbon microspheres are doped with other elements to activate persulfate due to their uniform particle size,high strength,and enhanced feasibility in practical applications.Based on this,the research plans to use FeCl₃·6H₂O and xylose hydrothermal carbonization to prepare a composite intermediate material（Fe O@XC）with a zero-valent iron core and a carbon shell on the surface,and use potassium borohydride to modify the intermediate material to prepare iron-carbon microspheres The composite（Fe@XB）,or the iron-containing carbonaceous microsphere composite（Fe@XC）modified with a high-temperature calcined intermediate,the two modified composites were used to activate persulfate for the treatment of organic wastewater,experimental selection Two typical refractory organic pollutants-organic azo dye wastewater RB5,organic phenol wastewater phenol.By means of material characterization,the degradation experiment phenomenon was analyzed,the decolorization effect of RB5,the destruction efficiency of naphthalene ring,and the degradation effect of phenol were evaluated,and the mechanism of the two composite materials activated persulfate to degrade organic pollutants was discussed.The specific conclusions are as follows:（1）Characterized by means of SEM,BET,XRD,XPS,EDS and FTIR,it is found that the three materials are spherical structures,the two modified materials are well compounded,and there are no other impurities except C,O,Fe,N,etc.It is also confirmed that the composite material is a carbon shell-wrapped zero-valent iron core structure,which proves that the surface has the redox effect of Fe3+,many oxygen-containing functional groups and unsaturated graphitic carbon,which provide active sites for the material to activate PS and provide pollutants.adsorption degradation and redox possibilities.The morphology and structure of the two modified materials changed little before and after the reaction,indicating that the prepared materials are very stable and will not easily disintegrate and deform.（2）The decolorization efficiency and naphthalene ring destruction efficiency of Fe@XB prepared by potassium borohydride reduction were over 95%and 48%,respectively;the degradation rate of Fe@XC activated PS to remove phenol was99.5%,when degrading dye RB5,the decolorization rate reached 99.2%,and the naphthalene ring destruction rate reached 74.3%,indicating that Fe@XC activated PS had better degradation effect than Fe@XB system,and degraded a wider range of pollutants and was more universal.（3）In the mechanism experiment analysis,it is concluded that the main active species in the degradation of RB5 by Fe@XB+PS system are ¹O₂,SO₄·^–and·OH,and the order of their influence on the reaction is ¹O₂>SO₄·^–>·OH,Fe The main active species in the degradation of phenol by Fe@XC+PS are·O₂^-,¹O₂,·OH and SO₄·^–,the relationship between active species and free radicals should be·O₂^->¹O₂>·OH>SO₄·^–,The reactions of both systems are dominated by non-radical reactions.And the two composite materials can maintain good recycling efficiency after repeated use for 2-3 times.