Magnetic nanoparticles (MNPs) are currently being intensively
investigated because of their extensive applications such
as drug release [1–4], magnetic resonance imaging [5–8], biological
separation [9,10] and water purification [11,12]. Among
them, water purification with magnetic materials is a new
research subject, which was reported by only a few papers.
For example, the work by Yavuz et al. reported successful
removal of arsenic from wastewater using monodisperse superparamagnetic
nanoparticles [11]. But it is difficult to reuse
superparamagnetic nanoparticles because the interaction between
iron oxides and arsenic is strong and irreversible. Zhao et al.
[12] employed superparamagnetic microspheres with Fe3O4@SiO2
core and porous SiO2 shell as a reusable absorbent to remove
microcystins from eutrophic water, however, silica is susceptible
to be corroded in harsh environment such as strong base
media.