Performance And Mechanism Of Metal-Organic Framework Derived Carbon-Based Catalyst For Pollutant Removal From Water

Exploring highly stable and efficient non-precious metal catalysts for decontamination of various non-biodegradable contaminants is a major challenge.In this paper,metal organic framework-derived carbon-based catalysts(Fe-Cu@N-C and FeS2/C@PVDF)were designed and prepared.Fe-Cu@N-C/PMS,Fe-Cu@N-C/HCOOH and FeS2/C@PVDF/PMS systems were constructed systematically for revealing the reaction mechanisms of catalytic oxidation or catalytic reduction of carbon-based materials,elaborating the purification process,and exploring the relationship between material structure and performance.Thus,we have provided new treatment methods of organic pollution and heavy metal ion pollution in water bodies.(1)Fe,Cu-coordinated ZIF-derived bimetal encapsulated N-doped carbon nanotube(Fe-Cu@N-C)was prepared by the pyrolysis of Fe and Cu coordinated ZIF-8 at 950℃in the N2 atmosphere,which was used as a novel bifunctional catalyst for the oxidation of organic pollutants and the reduction of CrⅥ.In addition,series of composite catalysts were prepared by changing the calcination temperature and metal source types to optimize the preparation conditions of the catalysts.The experimental results show that Fe-Cu@N-C has excellent activity and stability,and can effectively degrade organic pollutants by activating PMS,and reduce toxic CrⅥ with formic acid(HCOOH,FA)as the inducible reductant.It is found that singlet oxygen(1O2)is the main active substance for mineralization of organic pollutants in Fe-Cu@N-C/PMS system,and atomic hydrogen(H*)adsorbed on the catalyst surface is the main active substance for effective reduction of CrⅥ.Compared with other metal-coordinated ZIF-8 derivatives such as Fe@N-C,Cu@N-C and N-C,Fe-Cu@N-C exhibits significant catalytic activity,which is attributed to bimetallic active sites(Fe-Nx and Cu-Nx),high nitrogen doping levels,large surface areas and porous carbon structure and its electrical conductivity,which promote rapid mass transfer and enhance efficient electron transfer.In addition,the magnetic Fe-Cu@N-C composite is easily separated from the aqueous solution with the help of an external magnet.This study provides a new modulation strategy for the design of Fe-Cu bimetallic carbon and nitrogen catalytic materials for the removal of various pollutants.(2)The powder catalyst(FeS2/C)was prepared by synchronous carbonization and vulcanization of the precursor of Fe-MOFs.And the composite catalytic membrane(FeS2/C@PVDF)was prepared by phase conversion method.FeS2/C@PVDF/PMS reaction system was constructed for exploring the role of catalytic membrane in the process of catalytic activation of PMS to degrade organic pollutants,and exploring the reaction mechanism.XRD,FE-SEM,FE-TEM,XPS and other characterization techniques were used to analyze the morphology,composition and structure of the catalytic materials.Through free radical inhibitor experiment and electron paramagnetic resonance technology,the active species in the Fenton-like reaction system were identified,and the main species were SO4·-、HO· and 1O2.A series of characterization results and catalytic performance of FeS2/C and the FeS2/C@PVDF membrane show that the catalytic membrane has excellent catalytic capacity and high cycling stability.