Preparation Of Magnetic Straw/graphene Composites And Their Adsorption Properties For Pollutants In Water

In this paper,corn straw（CS）and graphene oxide（GO）were selected as raw materials,and straw/graphene composite（CS/GO）was prepared by solution blending method.On this basis,Fe₃O₄nanoparticles were loaded by hydrothermal method,and magnetic straw/reduced GO aerogel（m-CS/rGO）was prepared.The adsorption performance of these two adsorbents in various wastewater treatment was studied,such as the respectively adsorption of metal ions,dyes and antibiotics in sewage,the main contents and conclusions of this topic are as follows:（1）Corn straw was pretreated and cellulose was obtained from it,and then the cellulose and GO were used to prepare the straw/GO composite material（CS/GO）by blending method.The optimal preparation conditions of the straw/GO were investigated.Its structure was confirmed and analyzed by characterizations as SEM,BET,XRD,FT-IR and TGA.The adsorption properties of CS/GO adsorbent on metal ion Cr（Ⅵ）and organic cationic dye crystal violet（CV）were studied.The effects of different influencing factors on the adsorption of Cr（Ⅵ）and CV by CS/GO were investigated with the adsorption capacity as the index.The adsorption isotherm models of Cr（Ⅵ）and CV are in line with Langmuir isotherm model and Freundlich isotherm model,respectively.The maximum adsorption capacity is 235.79 mg/g and 239.17 mg/g,respectively,which is basically consistent with the experimental results.The straw/GO composite material in this study has the advantages of simple preparation,low cost and good adsorption effect.（2）Magnetic straw/reduced GO aerogel（m-CS/rGO）was prepared by the compositing Fe₃O₄nanoparticles with straw/GO.The structure of Fe₃O₄nanoparticles was analyzed by SEM,BET,XRD,FT-IR and TGA,and the loading of Fe₃O₄nanoparticles was confirmed.The effects of non-influencing factors on the adsorption of organic anion dye Congo red（CR）by m-CS/rGO were investigated.It is found that the adsorption process accords with the quasi-first-order kinetic model and Langmuir isothermal model.The maximum adsorption capacity of m-CS/rGO for CR is 128.52 mg/g,which is basically consistent with the experimental results.The addition of Fe₃O₄nanoparticles makes the adsorbent magnetic,which is conducive to recovery and adsorption of organic dye pollutants in the form of anionic ions.High adsorption efficiency can still be maintained after 6 cycles of retreatment.Compared with CS/GO,m-CS/rGO has better thermal stability and can be easily recycled under the action of external magnetic field,which expands its application range.（3）More application scenarios of the two adsorbents were explored.The adsorption properties of the quinolone antibiotic ofloxacin（OFL）were studied by using two adsorption materials respectively.The adsorption of OFL by CS/GO and m-CS/rGO conforms to the quasi-first-order kinetic model and the quasi-second-order kinetic model,respectively.The adsorption isotherm model of the two adsorbents conforms to the Langmuir isotherm model.The maximum adsorption capacity of CS/GO and m-CS/rGO for OFL was 533.60 mg/g and 499.93 mg/g,respectively.