Activation Of Persulfate By Fe-N-C@mSiO₂:study On Degradation Of Bisphenol A Under High Salt Condition

Bisphenol A(BPA)is an endocrine disruptor,which is highly biotoxic and difficult to degrade.It is widely found in A variety of industrial wastewater and is very harmful to human health.Due to the influence of the high salt condition in the industrial wastewater,the biological method and the advanced oxidation technology based on free radicals have obvious inhibition.In this paper,Bisphenol A as the target pollutant,through the development of A new activated material named Fe-N-C@mSiO₂.The factors affecting the degradation of bisphenol A by activated persulfate with new materials were studied under high salt condition.The morphology,crystal structure,pore volume and specific surface area of Fe-N-C@mSiO₂were characterized and analyzed by means of SEM,XRD,XPS,FT-IR,Raman spectroscopy and BET.The mechanism of the treatment system was preliminarily analyzed,and the degradation path of bisphenol A was speculated.The main research contents and conclusions are as follows:(1)On the basis of Fe-N-C material,Fe-N-C@mSiO₂material was successfully prepared by alkaline catalytic hydrolysis of silicon through the guide hole template method.The material is a rhomboid dodecahedron mesoporous material in the microscopic state,and has no nanoparticle formation and agglomeration phenomenon.(2)When the initial concentration of bisphenol A is 80mg/L,the concentration of sodium chloride is 50g/L,the initial p H is 7,the dosage of Fe-N-C@mSiO₂material is 0.5g/L,and the concentration of persulfate is 5mmol/L;The system can achieve the complete degradation of bisphenol A in 40 minutes.(3)Fe-N-C@mSiO₂material has good stability,after 4 cycle experiments,the system degradation rate of bisphenol A within 30 minutes can still reach 78%;The crystal structure of the material did not change.The metal leaching amount of Fe is0.0033mg/L,which is lower than the national emission standard.(4)Under the condition of high salt,free radical activation and non-free radical activation coexist in the process of peroxide sulfate oxidation of bisphenol A by Fe-N-C@mSiO₂;Singlet oxygen(¹O₂),sulfate radical(SO4^?-)and hydroxyl radical(?OH)are the main active oxidizing species.Moreover,¹O₂plays a dominant role.(5)The degradation of bisphenol A by Fe-N-C@mSiO₂activated persulfate under high salt conditions can be divided into two stages:adsorption and degradation.The adsorption process is in line with the pseudo-second-order reaction kinetics model,the equilibrium adsorption capacity is 63.743mg/g,and the adsorption reaction rate constant is 0.176min^-1.The degradation process conforms to the pseudo-first-order kinetics model,and the rate constant of degradation reaction is 0.1409min^-1.(6)The intermediate substances produced during the degradation of bisphenol A by activated persulfate from Fe-N-C@mSiO₂under high salt conditions were analyzed by GC-MS.It was speculated that the degradation path of bisphenol A was that the?fracture of carbon atoms connecting the two phenyl ring formed phenol and4-isophenyl phenol.The ring is then opened through dehydrogenation,oxidation and ring cracking reactions to form intermediate products such as 4-isopropylphenol,4-hydroxy-acetophenone and small molecular organic matter,and finally mineralized into carbon dioxide and water.