| The harm of industrial wastewater to human health and ecosystems is becoming more and more serious.Wastewater treatment has become a challenge that we have to face today and is a hot topic of research now.Therefore,development functionalized magnetic materials with highly absorption ability is the most important target in this paper.In this paper,the new adsorption material is preparedusing chitosan,Fe3O4 and dopamine as raw materials.The obtained Fe3O4/polydopamine/chitosan magnetic microspheres?Fe3O4/PDA/CS?as adsorbents are used in batch experiments to remove metal ions and dye from aqueous solutions.?1?The Fe3O4 magnetic microsphere is prepared by co-precipitation method.Fe3O4/polydopamine magnetic microsphere?Fe3O4/PDA?is prepared by using an in situ self-polymerization method.Finally the Fe3O4/PDA/CS is prepared by combing chitosanon and Fe3O4/PDA using 3-?triethoxysilyl?propyl isocyanateas the crosslinking agent.The obtained magnetic microspheres are characterized by means of scanning electron microscope?SEM?,transmission electronmicroscope?TEM?,fourier transform infrared spectra?FI-IR?,dynamic light scattering?DLS?,vibrating sample magnetometer?VSM?,X-ray diffraction?XRD?,energy dispersive spectrometer?EDS?,and X-ray photoelectron spectroscopy?XPS?,respectively.The results show that the XRD data of the synthesized Fe3O4 are in good agreement with the files for Fe3O4?PDF01-071-6336?.The coating of dopamine and chitosan does not change the crystal type of the Fe3O4.The average diameter of Fe3O4/PDA/CS is about 970 nm.The size distribution is more uniform.The thickness of coated chitosan is about 86.5nm.The saturation magnetization of the Fe3O4/PDA/CS is 38.2emu/g.Fe3O4/PDA/CS has good magnetic response.It can be separated with the water solution in a shorttime under an applied magnetic field.?2?The obtained Fe3O4/PDA/CS was used in batch experiments to remove metal ions(Cu2+,Hg2+,Pb2+)and dyes?rhodamineB,basic fuchsin and methylene blue?from aqueous solutions.The effects of adsorption time,adsorbent dosage,initial concentration of solution,pH of solution on adsorption were investigated.At the optimum adsorption conditions,the maximum adsorbance is 419.6mg/g,42.6mg/g,12.2mg/g,2.9mg/g,2.34mg/g,3mg/g and the maximum removal rate is 26%,85.2%,81.5%,70%,97.4%,99% for Cu2+,Hg2+,Pb2+,rhodamineB,basic fuchsin,andmethylene blue,respectively.?3?The adsorption isotherm and adsorption kinetics are investigated and analyzed.The results show that the adsorption process can be well fitted by the Langmuir equation and Freundlich equation and belongs to the monolayer-based mixed adsorption.The adsorption process can be well fitted by the pseudo-second-order model.Adsorption of magnetic microspheres is mainly attributed to the complexation ofamino and hydroxyl groups on dopamine and chitosan.?4?The regeneration and reusability of Fe3O4/PDA/CS is investigated.The Fe3O4/PDA/CS loaded with metal ions or dyes was desorbed using NaCl and ethanol,respectively,and then washed thoroughly with water for using in next adsorption to the correspondingmetal ions and dyes.The results show that the Fe3O4/PDA/CS has ahigher repeatability and can be used again. |
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