particles also exhibit high selectivity for the target pollutants from the environment
besides enabling ease of operation for reducing the particle separation steps from the
flowing stream. A comprehensive and systematic understanding of synthesis and
surface modifications of magnetic particles is significant to enhance their practicability in environmental technology. Although high removal performance and reactivity can be achieved by smaller particle size, the stability, toxicity, and recovery of
the particles magnetically could be challenging.
In contrast, the active surface of magnetic particles may be forfeited, while
surface modifications stabilize and reduce the toxicity of the particles. Reliable
surface modifications are necessarily needed for the increment of the number of
active sites to remove the heavy metals. For successful environmental applications of
the magnetic particles, modification on the magnetic particles is principally crucial to
balance the effects on their reactivity, capacity, and reusability.
Keywords Heavy metal ions · Magnetic particles · Contaminants · Heavy metal ·
Adsorbent · Pollution · Removal · Separation · Magnetic sorption technology
Nomenclature
ɣ-Fe 2 O 3
Maghemite
Ag
Silver
BH max
Highest energy product
B r
Remanence
Ca
Calcium
Cd
2+
Cadmium cation
CdS
Cadmium sulfide
CdSe
Cadmium selenide
Cu
Copper
Cu
2+
Copper cation
Co
Cobalt
Cr
4+
Chromium cation (4+)
Fe
Iron
FeO
À
Negative charge iron oxide
Fe 3 O 4
Magnetite
Fe 3 S 4
Greigite
Gd
Gadolinium
Hc
Coercive force
Hg
2+
Mercuric cation
HGMS
High-gradient magnetic separation
Mg
Magnesium
MIEX
Magnetic ion exchange resin
Mn
Manganese
MnFe 2 O 4 Manganese iron oxide
MnO
Manganese(II) oxide
Mn-Zn
Manganese-zinc
394
S.-F. Lim et al.