| Fe3O4-based magnetic materials have wide application in dye effluent treatment because of their low-toxicity, super-ferromagnetism and the diversity of their synthesis procedures. Various functional organic/inorganic molecules are used to modify Fe3O4. In the research about porous polymer functionalized Fe3O4 magnetic materials, to enhance the uniformity of the blending between the polymer and Fe3O4is the top task. In another aspect, the facile hydro/solvothermal method is also a hot topic in the synthesis of magnetic materials as the product of this method often permits the merits like low density and good mono-dispersity. We have studied the synthesis, characterization and the adsorption ability to cationic dye, Rhodamine B of the synthesized Fe3O4-based porous/hollow magnetic spheres.(1) Nine kinds of magnetic porous Fe3O4/poly(MMA-co-DVB) were synthesized using modified suspension polymerization with oleic acid modified Fe3O4 as the magnetic fluent, methyl methacrylate (MMA) and DVB (divinylbenzene) as the monomer and different small molecules as porogens. Specifically, toluene was used as the example of good solvent and cyclohexane was used as the example of bad solvent. The effect of the monomer ratio, the type and concentration of porogens to the pore structure of the synthesized spheres was investigated. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the structure of the synthesized spheres. Mercury intrusion method was used to test the pore structure of the product; X-ray powder diffraction (XRD) was used to characterize the crystallinity of the product and thermogravimetry (TGA) was used to characterize the amount of Fe3O4 in the product. The product was used as the adsorbent of cationic dye, Rhodamine B and the adsorption capacity was characterized using ultraviolet (UV) analyse to detect the concentration of un-treated and post-treated Rhodamine B solution. It was found that the type of porogens had a complex and dramatic influence of the pore structure of the synthesized spheres. When the good solvent, toluene was used as the porogen, the synthesized spheres tended to have higher surface area. The amount of porogens and the crosslinker, DVB also had significant influence to the pore structure. Decreasing the concentration of porogen and increasing the concentration of crosslinker are helpful to form integrated crosslinking structure and also it is helpful to include more Fe3O4. The XRD result showed that the coating of the polymer didn’t affect the crystallinity of the Fe3O4. SQUID result showed that the synthesized spheres possessed superparamagnetism. The adsorption experiment of the synthesized spheres showed that the synthesized spheres can adsorb as much as 90% of the initial Rhodamine B and the adsorption capacity of the spheres to Rhodamine B was 0.81mg/g.(2) Ten kinds of hollow magnetic Fe3O4/polyacrylic acid (PAA) spheres were synthesized using FeCl3·6H2O as the iron source, urea as the alkaline medium, sodium citrate as the reducing agent, PAA as the structure conducting agent and water as the solvent via hydrothermal synthesis method at 200℃. The effect of the reaction time and that of the amount of PAA to the synthesized spheres were investigated using SEM, TEM, XRD, vibration sample magnetometer (VSM) and N2 adsorption-desorption method. Furthermore, the hollow spheres synthesized under a standard situation were used as the model to adsorb Rhodamine B solution. It was found that the synthesis of the hollow spheres underwent an Ostwald ripening process, which means that with the increasing of time, firstly the primary particles were formed and then they aggregated into the secondary structure and formed hollow cavity. PAA acted as the structure directing and protecting agent in the reaction system and with the increasing of the amount of PAA, the hollow structure became clearer. The adsorption capacity of the synthesized hollow spheres to Rhodamine B was 2-4mg/g.(3) Eight kinds of magnetic hollow Fe3O4/PAA spheres were synthesized using FeCl3.6H2O as the iron source, PAA as the structure directing agent, water as the solvent via a hydrothermal synthesis under 200℃ and different alkaline conditions. We investigated the effect of different alkalines to morphology, chemical composition, crystallinity and magnetism of the synthesized spheres. Sodium carbonate, sodium hydroxide and sodium malonate were used as the alkaline sources, specifically. It was found that the pore structure of the spheres synthesized under different alkaline conditions varied. The spheres synthesized using sodium hydroxide possessed most clear hollow structure and the smallest particle size; the spheres synthesized using sodium malonate possessed smaller cavity and bigger particle size. The spheres synthesize using sodium carbonate appeared in solid form instead of hollow structures. All the spheres synthesized under different alkaline conditions possessed clear Fe3O4 crystallinity. The magnetism of the spheres synthesized under different alkaline conditions varied and the spheres synthesized using sodium malonate possessed highest saturated magnetization. The pore structure and distribution of the synthesized spheres varied with the change of the alkaline types. |
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