| The purpose of this work is to prepare a novel metal-organic framework（MOF）-derived magnetic mesoporous carbon material for the adsorption of dye wastewater.During the experiment,using 1,4-naphthalenedicarboxylic acid（1,4-H2NDC）rich in carboxyl groups as organic ligands,and Fe Cl3·6H2O and Zn（NO3）2·6H2O as metal sources,the bimetallic Fe/Zn-MOF precursor was synthesized by solvothermal method firstly,and then MOF-derived iron based magnetic mesoporous carbon materials（Fe-MPC）were prepared by calcination at high temperature.Moreover,in order to obtain the best preparation conditions of Fe-MPC,the influence of the solvent（type）,the addition amount of template agent,namely cetyltrimethylammonium bromide（CTAB）,the molar ratio of iron to zinc,and calcination temperature on the adsorption efficiency of Fe-MPC were investigated in detail by selecting malachite green as the target pollutant.In addition,the Fe-MPC prepared under optimal conditions was characterized by various modern analytical techniques.Based on these results,a quadratic polynomial regression model was established using the decolorization efficiency of malachite green in 90 min as the response value through single factor and response surface experiments,and the optimal adsorption parameters of malachite green by Fe-MPC were determined.Furthermore,the adsorption kinetics and thermodynamics of experimental data were analyzed,and the adsorption mechanism was discussed by combining the Raman and infrared spectra of the adsorbent before and after the reaction.Finally,the adsorption selectivity of Fe-MPC was examined by comparing the adsorption performance of the adsorbent to the other two dyes.The specific experimental results are as follows:（1）The Fe-MPC absorbent prepared under the conditions of water as solvent,the addition amount of CTAB as 1.5 mmol,the molar ratio of iron to zinc as 1:2 and the calcination temperature as 1000 oC had the best adsorption performance for malachite green.Its specific surface area and pore volume were 83.028 m2/g and 0.417 cm3/g,respectively,and the pore diameter was mainly between 3 and 7 nm.Magnetic particles of Fe3C were uniformly distributed inside the absorbent,and a large number of carboxyl and hydroxyl groups existed on its surface.（2）The order of the influence of various factors on the decolorization efficiency for malachite green was adsorbent dosage>initial concentration>initial pH>temperature,among which the interaction between the initial concentration and the amount of adsorbent as well as the initial pH and the amount of adsorbent on the adsorption of malachite green by Fe-MPC was the most significant.It was calculated that when the initial concentration was 308 mg/L,the dosage of Fe-MPC was 0.78 g/L,the pH was 7.6,and the temperature was 299 K,the maximal adsorption efficiency of malachite green was obtained,and the estimated value of decolorization efficiency was98.34%,which was basically consistent with the experimental value.（3）The adsorption of malachite green by Fe-MPC followed the quasi-second-order kinetics and Langmuir adsorption isotherm model.The saturated adsorption capacity of Fe-MPC for malachite green at room temperature was up to 840.37 mg/g.In addition,the thermodynamic parametersΔG,ΔH,ΔS and average free energy E were calculated to be-14.69～18.77 KJ/mol,24.48 k J/mol,136.02 J/（mol·k）,and 9.53～10.56KJ/mol,respectively.Combined with the effect of initial pH of solution on adsorption,and the Raman spectrum and Fourier infrared spectrum of FE-MPC before and after adsorption,it was concluded that the mechanisms of adsorption for malachite green onto Fe-MPC were attributed to a combination of electrostatic interaction,π-πstacking interaction,hydrogen bond and pore filling,among which electrostatic interaction played a leading role.（4）Fe-MPC had certain adsorption properties for the other two dyes,namely methylene blue and golden orange Ⅱ,but the adsorption efficiency of positively charged methylene blue was obviously better than that of negatively charged golden orange Ⅱ. |
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