| Graphene has been widely used in the fields of adsorption and extraction due to its high mechanical strength,large surface area and good stability.Magnetic graphene combines the merit of easy to separate of magnetic nanoparticles and ideal adsorption capacity of grapheme,becoming a hot spot.In recent years,the residual of antibiotics in environment has attracted much attention.In this study,magnetic graphene nanocomposites were prepared by a chemical coprecipitation method.The morphology and crystal structure of the prepared samples were characterized.The adsorption experiments were carried out by adsorping two typical tetracycline antibiotics(including oxytetracycline hydrochloride and tetracycline hydrochloride)from water.Experimental results show:(1)Through a chemical coprecipitation method,magnetic grapheme was prepared.Scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR)and Magnetic properties measurement system(MPMS)show the material has a pleated structure,which can provide a rich locus for adsorption,and the magnetic particles are evenly distributed on graphene.The surface area of the material is 232 m~2/g,the pore volume is 0.24 cm~3/g,and the average pore size is 5.85 nm,which belongs to the mesoporous material.The saturation magnetization of material is 26 emu/g,which can be used in magnetic solid-liquid separation.(2)Adsorption of two typical tetracycline antibiotics,oxytetracycline and tetracycline hydrochloride,were studied by using magnetic graphene adsorbent.The effects of the dosage of adsorbent,the concentration of initial antibiotics,the pH of solution,temperature,ionic strength and other factors on the adsorption process were investigated in batch experiments.The results showed that the best adsorption effect was obtained when the dosage of adsorbent was 10 mg,the initial concentration of antibiotics was 10 mg/L,the pH was 7,the temperature was 40?.(3)Adsorption isotherm,adsorption kinetics,adsorption thermodynamics analysis showed that showed that the adsorption process was in accordance with the Langmuir isotherm equation and the pseudo-first-order kinetic equation.The adsorption process was endothermic and increasing of temperature is conducive to occurrence of adsorption from30?to 40?.The adsorption mechanism is mainly?-?interaction and electrostatic interaction.At the same time,the adsorbent was desorbed and reused,and it was proved that the removal efficiency only decreased 9%after 5 cycles.(4)The magnetic graphene nanomaterials were applied to the adsorption of the actual water.Under the condition of the amount of adsorbent 60 mg,pH of 7,contact time of 60 min,temperature of 40?,the removal efficiencies of magnetic graphene to oxytetracycline hydrochloride and tetracycline hydrochloride in tap water,pool water and lake water were81.3~96.4%and 80.7~99.5%,93.9~98.3%and 97.8~98.8%,90.5~98.2%and 97.9~99.5%,respectively.The experimental results show that the nanocomposites have great potential in the adsorption of tetracycline antibiotics in water. |
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