| The main purpose of this research is fabricating of novel composite material with high adsorption performance toward a wide range of pollutants in wastewater.Recently,Metal Organic Frameworks（MOFs）as organic porous materials attracted more attention since these materials have high surface area,adjustable pore size and structure,and is easy to modify and functionalize its surface.There are various types of MOFs,among them MIL-101（Materials of Institute Lavoisier-101）due to its excellent physical and chemical properties,stable structure,outstanding adsorption performance,etc.,is considered as a suitable adsorbent to remove various pollutants in water.For this reason.In this study,MIL-101（Fe）was selected as basic material which was modified with Cu to fabricate a bimetallic MOFs material named MIL-101（Fe,Cu）with two metal centers,large specific surface area and good adsorption capacity.Then graphene oxide（GO）was synthesized with MIL-101（Fe,Cu）/GO to compose a new adsorbent with abundant active sites for adsorption of pollutants.The influencing parameter such as the molar ratio of iron and copper and the amount of added GO were discussed on the removal of phosphate,hexavalent chromium（Cr（Ⅵ））and dyes including anionic dye（Congo Red,CR）,cationic dye（Methylene Blue,MB）from stimulated wastewater.XRD,SEM,N2adsorption-desorption isotherm analysis,FT-IR,XPS and zeta potential analysis were conducted to analyze the characterization of the composite material and its adsorption capacity.the contents of this research are mainly as following:（1）The characterization experiment results showed that the MIL-101（Fe,Cu）/GO composite material has been successfully synthesized with uniform arrangement,and clear structure.The addition of Cu can cause lattice distortion of the original MIL-101（Fe）crystal,increasing the specific surface area of the material by 31.72%;and the addition of GO connects the MIL-101（Fe,Cu）crystal and its lamellae to each other.A dense and compacted structure is formed,with high specific surface area and pore volume.The incorporation of Cu and the addition of GO respectively solved the problems of unsatisfactory adsorption capacity of MIL-101（Fe）and easily suspension of light particles in the aqueous solution.（2）According to the experimental results the best molar ratio for iron-copper was 4,and addition of GO ratio was 2%for the satisfactory adsorption of phosphate by MIL-101（Fe,Cu）/GO composite material.But adding excessive copper and GO will cause certain negative effects.The equilibrium contact time for adsorption of phosphate in three different samples were120 minutes,and the adsorption effect was better under acidic conditions,while high temperature was not favorable to adsorption processes.The maximum adsorption capacity of MIL-101（Fe,Cu）/GO toward phosphate was 204.60mg·g-1.Based on experimental results the adsorption kinetic data was fitted more with the second-order kinetic model,and the adsorption isotherm is similar to the Langmuir model,and the adsorption thermodynamic model displayed that the adsorption process is self-emitting.The composite materials showed a good recyclability and its adsorption mechanism was mainly via electrostatic and formation of coordination bonds for phosphate removal.（3）The adsorption experiment results of MIL-101（Fe,Cu）/GO for the removal of Cr（Ⅵ）showed that the adsorption reached at equilibrium point within 180 min,the lower the pH and temperature the better the adsorption performance of the composite material.The maximum adsorption capacity of MIL-101（Fe,Cu）/GO on Cr（Ⅵ）is 67.82mg·g-1.The main adsorption mechanism of MIL-101（Fe,Cu）/GO on Cr（Ⅵ）was via electrostatic interaction.（4）The adsorption experiment results of MIL-101（Fe,Cu）/GO showed that the adsorption of MIL-101（Fe,Cu）/GO on CR and MB reached at equilibrium within 120 minutes.The adsorption of CR was favorable at low pH condition while MB adsorption was better under high pH condition.The maximum adsorption capacity of MIL-101（Fe,Cu）/GO for CR and MB is724.71mg·g-1 and 543.59mg·g-1,respectively.In contrast,the composite material had a better adsorption effect on anionic dyes.The main adsorption mechanism of MIL-101（Fe,Cu）/GO on CR and MB was via electrostatic andπ-πstacking.In summary,the MIL-101（Fe,Cu）/GO composite adsorbent synthesized in this study has an ideal removal effects on several types of pollutants in water,and basically meets the research goals.This composite material provides the chance for the development of new adsorbent material for wastewater treatment. |
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