| Recently, the frequent occurrence of heavy metal contamination makes it urgent for us to prepare a novel adsorbent material which can be low-cost, easily separated, high adsorption performance and reusable, magnetic composites, which may be a combination of adsorbent materials and magnetic nanoparticles, not only can effectively take up heavy metal ions in water, but also can use magnetic separation technology to recycle the adsorbents. This paper successfully prepared several kinds of the magnetic composites by simple, green and low toxicity methods, and explored the adsorption behavior for Pb(Ⅱ). It mainly included the following details:(1)First, Fe3O4 magnetic nanoparticles were prepared by hydrothemal method. And then a novel Fe3O4@PPy/PPy magnetic composites, grafting core-shell structure Fe3O4@PPy magnetic nanoparticles on the polypyrrole films, has been successfully synthesized via in situ polymerization of pyrrole monomer in the presence of Fe3O4. The article investigated the effect of the amount of Fe3+ and APS on the structure of final materials. The magnetic hysteresis measurement reveals the superparamagnetic character of Fe3O4@PPy/PPy, and its saturation magnetization is 17.27 emu/g.(2)Fe3O4@PPy/PPy was used as an adsorbent for Pb(Ⅱ) removal, and the influences of experimental parameters, including the initial pH value, initial concentration, contact time and temperature, were investigated in detail. The adsorption mechanism was studied by adsorption kinetics, adsorption isotherms and adsorption thermodynamic, and the reuse ability of Fe3O4@PPy/PPy was also investigated. The results indicated that the adsorption capacity was closely related to pH. The adsorption process of Fe3O4@PPy/PPy for Pb(Ⅱ), which was spontaneous and endothermic, could be well fitted to the pseudo-second-order model and Langmuir model. After five adsorption-desorption recycle experiments, there was no obvious loss in the adsorption capacity of Fe3O4@PPy/PPy for Pb(Ⅱ). Together, it is demonstrated that Fe3O4@PPy/PPy is a potential low-cost,reusable and eco-friendly adsorbent for Pb(Ⅱ) removal from wastewater.(3)ZnFe2O4/PAA, ZnFe2O4/rGO and ZnFe2O4/rGO/PAA composites were successfully prepared through a facile and effective one-pot solvothermal method. Their hysteresis loop reveals the ferromagnetic behavior of ZnFe2O4/PAA, ZnFe2O4/rGO and ZnFe2O4/rGO/PAA composites at room temperature, their saturation magnetization are 53.70,45.67 and 41.22 emu/g, respectively.(4)The adsorption behavior of Pb(II) on ZnFe2O4/PAA, ZnFe2O4/rGO and ZnFe2O4/rGO/PAA composites were investigated, and Influencing factors for Pb(II) adsorption, such as pH value, contact time, initial concentration and temperature, were mainly discussed. The adsorption mechanism was investigated by adsorption kinetic, adsorption isotherm and adsorption thermodynamics. The resluts showed that it is best for the adsorption efficiency of ZrFe2O4/rGO/PAA composites in the three kinds of adsorbents. By exploring five recycling experiment of ZnFe2O4/rGO/PAA, it is found that the adsorption efficiency is still more than 90%, indicating that ZnFe2O4/VrGO/PAA composites is a potential reusable, effective and green adsorbent. |
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