Synthesis And Environmental Purification Properties Of Iron And Carbon/Graphite Phase Carbonitride Composites

In this thesis,carbon/graphite phase carbon nitride（C/g-C₃N₄）with visible light catalytic activity and ferric oxide/carbon/graphite phase carbon nitride with magnetic separation performance（Fe₃O₄-C/g-C₃N₄）were designed and synthesized.Two major types of composite materials for the treatment of organic pollutants and trivalent arsenic pollution in water Environment.The specific research contents are as follows:Partially hydroxylated melamine（MF）was synthesized from formaldehyde and melamine,and C/g-C₃N₄ composite was prepared by simple one-pot roasting method with MF as precursor.The prepared materials were subjected to Fourier transform infrared spectroscopy（FT-IR）,thermogravimetric（TG）,X-ray diffraction（XRD）,photoluminescence spectroscopy（PL）,scanning electron microscopy（SEM）and transmission electron microscopy（TEM）,electrochemical impedance（EIS）and specific surface area and pore size analysis（BET）were characterized.The effects of the molar ratio of formaldehyde to melamine on the carbon content,specific surface area and photocatalytic properties of the materials were investigated.The research shows that when the molar ratio between formaldehyde and melamine is 1:0.5,the carbon content and specific surface area of the obtained composite materials are 3.5%and 62.74 m²g^-1,respectively,and the photocatalytic degradation rate constant of methylene blue（MB）is 1.9 times higher than that of pure g-C₃N₄.At the same time,the results of the mechanism study indicate that the hydroxyl radical（·OH）is the main oxidation active group.The C/g-C₃N₄ composite prepared in the first part and FeCl₃·6H₂O and FeCl₂·4H₂O were used as the main raw materials.Fe₃O₄-C/g-C₃N₄ with visible light activity and magnetic separation performance was synthesized by solvothermal reaction.The synthesized Fe₃O₄-C/g-C₃N₄ was characterized by TEM,TG,XRD,VSM,high power transmission electron microscopy（HRTEM）and BET.The effects of Fe₃O₄ loading on the photocatalytic performance and arsenic removal efficiency of the composites were investigated.The results show that Fe₃O₄-C/g-C₃N₄ can achieve synergistic photocatalytic oxidation and adsorption of As（III）under visible light conditions.When the Fe₃O₄ mass fraction is 12.90,he removal rates of total arsenic and trivalent arsenic reach 81.98%and 84.86%.The mesoporous mp-C/g-C₃N₄ was prepared by using silica as a hard template and MF as a precursor,and Fe₃O₄ was coprecipitated again to obtain a mesoporous high specific surface area mp-Fe₃O₄-C/g-C₃N₄ material.The materials were characterized by TEM,TG,XRD,VSM,HTEM,BET and so on.The results show that when the C content in the composite is 3.47wt%and Fe₃O₄ is 12.50wt%,the removal rates of total arsenic and trivalent arsenic reach 96.87%and 98.07%,respectively.The photocatalytic oxidation mechanism indicates that the pores（h⁺）and superoxide anion radicals(·O^2-)are the main active oxidants.