Synthesis Of Magnetic Metal-Organic Frameworks And Their Applications In Solid Phase Extraction

The increasing contamination of organic dyes not only deteriorates the water quality,but also has a significant impact on human health due to its toxic,carcinogenic,and mutagenic effects.Therefore,it is crucial to develop simple,rapid and efficient methods for the treatment of dye-containing effluents before they are discharged into the environment.In this paper,three kinds of magnetic metal-organic framework materials were synthesized:Fe3O4@SiO2/HKUST-1,Fe3O4@SiO2-Cu-BTC,ZIF-8@CoFe2O4,respectively.As extraction agents,they can be used to extract dye molecules from aqueous solution and they are easily to be separated by applying extra magnet.The magnetic Fe3O4 particles are prepared by hydrothermal method and firstly modified by SiO2,the magnetic particles were then added into the precursor solution of synthesizing HKUST-1.The Fe3O4@SiO2/HKUST-1 composites are obtained by hydrothermal synthesis method.The as-prepared Fe3O4/HKUST-1 composites were characterized and applied to the removal of Congo Red dye from aqueous solution.Under the condition of pH 7,the Fe3O4@SiO2/HKUST-1 shows good adsorption activities towards CR,with maximum adsorption capacity of 49.5 mg·g-1 and removal efficiency of 98%when 10 mg of composites and 5 ml CR(32 mg·L-1)were used.Also,Fe3O4@SiO2/HKUST-1 not only has a high stability in pure water and ethanol,but also exhibits high removal efficiency of above 90%towards Congo Red for at least four cycles of desorption-adsorption experiments,indicating its reusability during magnetic solid phase extraction process.The magnetic Fe3O4 particles are prepared by hydrothermal method and modified by SiO2,then mixed with the as-prepared Cu-BTC material to obtain the magnetic Fe3O4@SiO2-Cu-BTC adsorbent after ultrasonic treatment.The adsorption of Congo red dye on Fe3O4@SiO2-Cu-BTC was studied in detail,including the effects of the amount of adsorbent,time of reaction,concentration of dye,ionic strength and pH.The isothermal adsorption models,adsorption kinetics and thermodynamics are simulated to investigate the potential adsorption mechanism.The CoFe2O4 particles prepared by hydrothermal method was firstly modified by poly(N-vinyl-2-pyrrolidone)(PVP),and then used to fabricate ZIF-8@CoFe2O4 through layer-bylayer method.The adsorption behaviors of ZIF-8@CoFe2O4 toward Congo red and Basic Red 2 dye were studied systematically,including the effects of the time of reaction,concentration of dye and pH.In order to investigate the adsorption mechanism,the isothermal adsorption models,adsorption kinetics and thermodynamics are simulated,respectively.This study provides an effective approach for the design and synthesis of the other stable magnetic core-shell materials.