Research Of Phosphate Removal Adsorbent Based On Metal Organic Framework Materials

In recent years,metal-organic frameworks（MOFs）,as a new type of porous material,have attracted much attention because of its good performances in adsorption,sensing,catalysis,hydrogen storage and separation.In this paper,a variety of metal organic frameworks were prepared to study the adsorption behavior of phosphate removal.The main research results are as follows:（1）The MIL-101（Fe）and Fe₃O₄@MIL-101（Fe）were synthesized by hydrothermal method and characterized by X-ray diffraction（XRD）,Fourier transform infrared（FTIR）,Scanning electron microscopy（SEM）.The results showed that MIL-101（Fe）was successfully coated on Fe₃O₄,and synthesized a core-shell structure Fe₃O₄@MIL-101（Fe）.The removal of phosphate by Fe₃O₄@MIL-101（Fe）was deeply studied,including the influences of adsorption dosage,pH and adsorption time on the adsorption process,and the adsorption kinetics and adsorption isotherm were fitted.The results showed that the adsorption kinetics fit the pseudo-second-order kinetic and the isotherms correspond to Langmuir model.Compared with other common adsorbent,Fe₃O₄@MIL-101（Fe）has good adsorption effect.Meanwhile,the adsorbents with adsorbed phosphate can be separated quickly under magnetic field after adsorption which a simple and effective method for the removal of phosphate were developed（2）The La-MOFs were synthesized by hydrothermal method and characterized by XRD,FTIR,SEM and Zeta potential.The results showed that the La-MOFs were successfully synthesized.The effects of adsorbent dosage,pH value and adsorption time on the adsorption of phosphate were investigated.The experimental data showed that the adsorption of phosphate by La-MOFs was more in accordance with the pseudo-second-order kinetics model and Langmuir isotherm model,and the adsorption mechanism was deduced as electrostatic attraction and ligand exchange.In addition,the adsorption capacity of La-MOFs on phosphate was greatly improved compared with Fe₃O₄@MIL-101（Fe）,which indicated that La-MOFs had great potential for phosphate adsorption.（3）NH2-La-MOFs were prepared via hydrothermal synthesis and characterized by XRD,FTIR,SEM,energy dispersive X-ray spectroscopy（EDX）and Zeta potential.The removal ofphosphate by NH2-La-MOFs was deeply studied.Adsorption experiments were carried out as a function of adsorption dosage,pH and adsorption time.The results showed that the adsorption effect of the material was good,and the adsorption rate was fast.The adsorption kinetics was in accord with the pseudo-second-order kinetic model,and the thermodynamics accorded with the Langmuir model.Based on the ATR-FTIR of NH2-La-MOFs,it is proved that the adsorption of NH2-La-MOFs on phosphate is chemically adsorbed.