| Polycyclic aromatic hydrocarbons(PAHs)are a common organic contaminant,and humans produce many organic pollutants like polycyclic aromatic hydrocarbons in production and life.This organic substance has certain carcinogenicity and difficult to be degraded,so researchers have conducted extensive research on the removal of such organic matter.It is a simple and effective method to select a suitable adsorbent for adsorption elimination of polycyclic aromatic hydrocarbons.The ability to develop adsorbents with high specific surface area,adjustable morphology,conducive to separation after adsorption,and high-efficiency regeneration has become a hot concern.Two magnetic metal-organic framework composites with magnetic properties were synthesized herein.One is CuFe2O4/Cu-organic framework(HKUST-1)synthesized in situ with copper ferrite,and the other is directly loaded onto the copper metal organic skeleton by Fe3O4 to form Fe3O4/Cu-organic framework composite.The two materials are CuFe2O4 and HKUST-1 as the main adsorbing materials.Firstly,CuFe2O4 has a large specific surface area,and copper can provide metal active sites,which is beneficial to the adsorption of polycyclic aromatic hydrocarbons.Because of its excellent magnetic properties,it is easy to magnetically separate and improve the reproducibility.However,nano-sized CuFe2O4 is very easy to agglomerate.Therefore,CuFe2O4 releases part of Cu2+ to directly form HKUST-1,while HKUST-1 supports unreacted CuFe2O4.In addition to CuFe2O4 agglomeration,HKUST-1 and organic pollutants easily form ?-? hydrophobic bonds,which is beneficial to capture organic pollutants in water.Secondly,we synthesized Fe3O4/HKUST-1,which is a good adsorbent because HKUST-1 has strong ability to capture organic matter in water and provides active metal sites.However,it is easy to cause structural damage during the recycling process,which is not conducive to its separation and recycling.Therefore,this paper loads Fe3O4 to HKUST-1,which improves the separation ability and increases its regenerability.The main research contents are as follows:Firstly,the preparation methods of these two magnetic composite materials were studied,and two magnetic composite materials were successfully synthesized.(1)CuFe2O4/HKUST-1 was synthesized by in-situ solvothermal method.Pre-synthesized copper ferric acid is used as a raw material for the synthesis of HKUST-1.At a certain temperature,CuFe2O4 releases copper ions,and copper ions react with organic ligands to form a copper organic framework(HKUST-1),while copper and iron The acid is directly loaded on the surface of HKUST-1.(2)During the formation of HKUST-1,Fe3O4 was added to form Fe3O4/HKUST-1 magnetic composite at a certain temperature and pressure.A series of analyses of XRD,SEM,TEM,IR,etc.It was carried out on the two composites,and it was thus proved that we successfully synthesized two magnetic metal organic framework.Secondly,the adsorption of naphthalene in aqueous solution by CuFe2O4/HKUST-1 was studied.The adsorption performance and mechanism were explored from the perspective of kinetics and thermodynamics.According to the kinetic model results,the magnetic composite is suitable for the quasi-second-order kinetic model for different initial concentrations of naphthalene solution.It is indicated that the naphthalene molecule is extracted by two functional sites,and its adsorption is predictable.Through the thermodynamic isotherm model,the adsorption of naphthalene by the composite conforms to the Freundlich,Temkin and D-R equations.The Freundlich adsorption model demonstrates that the adsorption of naphthalene by the material is heterogeneous and belongs to multi-molecular layer adsorption.The Temkin model shows that the adsorption of naphthalene by this material is an endothermic process.In subsequent thermodynamic studies,?H0 greater than zero verified its endothermic process.The D-R equation mainly indicates whether the adsorption process is physical adsorption or chemical adsorption.It is proved by experiments that the adsorption of naphthalene by CuFe2O4/HKUST-1 is a physical process.Through the exploration of the adsorption mechanism,it was found that the material is copper ferric acid as a main adsorption active material,and HKUST-1 acts as a substrate to uniformly disperse copper ferrite on the surface,thereby avoiding the aggregation of copper ferrite.The adsorption of this material is mainly because the copper ions in the ferroferric acid can provide active metal sites.In addition,HKUST-1 can form a ?-? interaction with naphthalene,thereby increasing the capture ability of naphthalene.Third,the adsorption properties and research mechanism of magnetic HKUST-1 were explored.The adsorbent is mainly based on HKUST-1,testing the adsorption performance and mechanism of HKUST-1,and the synergistic effect of magnetic material Fe3O4,and elucidating the adsorption effect of magnetic material on HKUST-1.Through performance test,it was found that the adsorbent adsorbed naphthalene conformed to the quasi-second-order kinetic model and accorded with three adsorption models of Freundlich,Temkin and D-R.It is indicated that Fe3O4/HKUST-1 magnetic composite is multi-molecular layer adsorption,which belongs to physical adsorption and is an endothermic process.However,compared with pure HKUST-1,its adsorption amount is obviously improved,indicating that HKUST-1 supports Fe3O4 to naphthalene.The adsorption has a synergistic effect.At the same time,Fe3O4/HKUST-1 has magnetic properties,which improves the adsorption regeneration performance and reduces the adsorption cost. |
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