Separation of Fe3O4 Nanoparticles from Water by Sedimentation in a Gradient Magnetic Field


Sedimentation dynamics of magnetite (γ-Fe3O4) nanopowders (10 - 20 nm) in water in the presence of a gradient magnetic field was studied by optical and Nuclear Magnetic Resonance (NMR) relaxometry methods. The magnetic field B ≤ 0.3 T, dB/dz ≤ 0.13 T/cm was produced by the system of permanent strip magnets. The initial sedimentation rate of the nanoparticles in water and under magnetic fields is higher for less concentrated suspensions (c0 = 0.1 g/l) than for more concentrated ones (c0 = 1 g/l). This might be connected with the formation of gel structures due to strong magnetic attraction between ferromagnetic nanoparticles. In the gravitation field, the suspensions of the particles (10 - 20 nm) remain stable for over 20 hours. The sedimentation process can be greatly accelerated by the action of a vertical gradient magnetic field, reducing the sedimentation time down to several minutes. In a gradient magnetic field enhanced by a steel grid, sedimentation of the nanopowder (c0 = 0.1 g/l) for 180 minutes resulted in reduction of the iron concentration in water down to 0.4 mg/l. In flowing water regime, the residual iron concentration in water 0.3 mg/l is reached after 80 minutes.

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Medvedeva, I. , Bakhteeva, I. , Zhakov, S. , Revvo, A. , Uimin, M. , Yermakov, A. , Byzov, I. , Mysik, A. and Shchegoleva, N. (2015) Separation of Fe3O4 Nanoparticles from Water by Sedimentation in a Gradient Magnetic Field. Journal of Water Resource and Protection, 7, 111-118. doi: 10.4236/jwarp.2015.72009.

Conflicts of Interest

The authors declare no conflicts of interest.


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