Preparation And Property Evaluation Of Metal-free Doped Carbon Encapsulated Metal Nanoparticles Loaded With PVDF Mebmrane

This paper is focused on the scientific issues such as the structure control and synergistic mechanism of the functionality composite membrane for catalytic reaction.Based on the strong biological toxicity and poor biodegradation of persistent organic pollutants.To solve these issues,this article provides the strategy for optimizing the surface structure and electronic transport of combining active metal nanoparticles and PVDF membrane for improving the catalytic activity.The novel nonmetallic doped carbon encapsulating metal nanoparticles loaded with polyvinylidene fluoride(PVDF)were designed and prepared combining with the compsite material forming mechanism.The movel catalytic reaction systems were established for pollutants removal,the structure activity relationship among the composition,structure and catalytic performance were further clarified.The following studies were carried out:(1)Iron nanoparticles(NPs)embedded in S,N-codoped carbon were prepared by one-step pyrolysis of ahomogeneous mixture consisting of Fe,S,N,C precursors,and then immobilized in poly(vinylidenefluoride)membranes as a multifunctional catalytic system(NSC-Fe@PVDF)to effectively activate perox-ymonosulfate(PMS)and oxidize organic compounds in water.The surface morphology and the structure of the compsite membrane was characterized by a series of microscopic techniques,the results indicated that a uniform distribution of the NSC-Fe nanoparticles on the PVDF scaffold.The excellent catalytic was mainly ascribed to the synergistic effects between the metal iron NPs and nitrogen-doped carbon nanotubes.And the effects of several operational factors,such as reaction temperature,solution pHs as well as PMS dosage were extensively evaluated.Besides,high surface area and porous structure of composite membrane enable facile transport and penetration of catalytic reactants to the active surface without suffering high mass-transfer resistance,which led to the enhancement of catalytic performance.It can avoid the loss and aggregation of the metal nanoparticles,and solve the drawbacks about the secondary pollution of deactivated catalyst.In addition,the cycle experiments revealed that the catalyst had excellent stability and recyclability.Moreover,Inhibition experiments and the electron spin resonance spectrometer(ESR)proved that SO4·-and ·OH were generated in the Fenton-like reaction,and thus,the catalytic degradation mechanism was proposed.(2)MoxNiy@N-C catalysts were fabricated conveniently using melamine,oxalic acid,ammonium molybdate tetrahydrate and nickel chloride hexahydrate as raw materual,and then loaded on poly(vinylidene fluoride)film to obtain the MoxNiy@N-C/PVDF catalytic membranes(where x and y represented the amounts of molybdenum source and nickel source).The membranes effectively catalyzed the reduction of toxic Cr? to benign Cr? by employing formic acid(HCOOH)as the reducing agent.Owing to the synergistic effects amongst Ni0,MoxC,aoped nitrogen,and oxygen groups as catalytic active sites,and carbon shell protection of metal NPs from leaching out,MoxNiy@N-C/PVDF catalysts exhibited excellent catalytic activity and recyclable capability for Cr? reduction.The membrane's unique porous structure and large chemically active surface area not only minimize the NPs agglomeration,but also allow the facile transport of catalytic reactants to the active surface without suffering from high mass-transfer resistance.The catalytic experiments revealed that Mo0.27Ni0.4@N-C/PVDF/HCOOH system had the best removal efficiency.Therefore,the effects of several reaction conditions,such as initial Crvl concentration,inorganic anions,initial pH reaction temperature were investigated using Mo0.27Ni0.4@N-C/PVDF/HCOOH system.This study demonstrates catalytic membrane with the morphological and structural features provide a green,economic,and fast method for the treatment of Cr? containing wastewaters.