A facile method for synthesis of the magnetic Fe

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nanoparticles was introduced. Magnetic nanoparticles were prepared via co-precipitation method with (PMF) and without (AMF) 0.15 T static magnetic field. The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD

TEM

SEM

VSM and BET. The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe

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nanoparticles but improved the crystallinity. The morphology of Fe

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nanoparticles was varied from random spherical particles to rod-like cluster structure. The VSM results indicated that the saturation magnetization value of the Fe

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nanoparticles was significantly improved by the magnetic field. The BET of Fe

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nanoparticles prepared with the magnetic field was larger than the control by 23.5%. The batch adsorption experiments of Mn(II) on the PMF and AMF Fe

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nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased. At pH 8

th

e Mn(II) adsorption capacity for the PMF and AMF Fe

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was reached at 36.81 and 28.36 mg·g

-1

respectively. The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe

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. The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(II) from aqueous solution.