Preparation And Application Of Graphitic Carbon Nitride

Increasing attention has been paid to graphitic carbon nitride?g-C₃N₄?due to its wide range of composition,excellent electrochemical properties and suitable band gap,which offer a range of potential application in the fields of battery,photocatalysis,photodegradation and environmental protection.g-C₃N₄ contains large amount of amino,oxazine ring structure and carries a positive charge under acid condition,thus it can be used as a heavy metal ion and organic pollutants adsorbent to treat industrial contaminants.And the lamellar structure of g-C₃N₄ is similar to the lamellar structure of TATB crystal,this might affect TATB crystal growth.In this paper,using g-C₃N₄ materials as the research object,its preparation methods and application properties in the industrial contaminants treatment and TATB crystal growth were explored.The main contents of the paper are as follows:?1?Using melamine and lithium chloride as raw material,the porous g-C₃N₄ was prepare by a two-steps thermal polymerization method.The composition,morphology,internal structure,specific surface area and pore volume of the prepared samples were characterized by the means of XRD,FTIR,XPS,SEM,TEM and BET.The specific surface area and average pore diameter of the prepared porous graphitic carbon nitride?P-g-C₃N₄?are 86.7m2/g and 7nm respectively.Compared with the bulk g-C₃N₄ prepared by simple thermal polymerization,the specific surface area of porous g-C₃N₄ is greatly improved.?2?The adsorption properties of g-C₃N₄ on the Pb???and methylene blue?MB?were studied by using as-prepared P-g-C₃N₄ and mass g-C₃N₄ as adsorbents.The adsorption capacity was tested by inductive coupling plasma emission spectrograph?ICP?and UV-Vis spectrophotometer.The adsorption kinetics,adsorption isotherms of P-g-C₃N₄ on Pb???were studied and Langmuir and Freundlich adsorption models were fitted to the adsorption isotherms.The effect of p H on the equilibrium adsorption capacity was studied and its recycling performance was explored.At the same time,the adsorption kinetics of P-g-C₃N₄ and mass g-C₃N₄ on MB were studied.The adsorption kinetic model of porous g-C₃N₄ on Pb???and the adsorption kinetic parametersof P-g-C₃N₄ and mass g-C₃N₄ on MB were obtained.?3?The TATB crystals with spiral structure were prepared by the solvent/non-solvent method with concentrated H2SO4 as solvent.The phase,morphology and surface composition of the crystals were characterized by XRD,SEM and Raman.The effects of supersaturation and crystallization time on the formation of TATB helical structure and the morphology of TATB were studied.The formation mechanism of TATB helical structure was explored.The TATB crystals obtained in the experiment were grown in a helical dislocation driven growth mode,and the formation of helical dislocations was due to defects caused by low lattice matching of g-C₃N₄ and TATB.