by an external magnetic field. The ferromagnetic property of Fe 3 O 4 nanoparticles
makes them appropriate for grafting these nanoparticles to other oilsorbents for easy
and quick reusability after sorption. Then ultrasonic washing treatment was used as
reuse method and indicated the reusability of magnetic sorbents.
Coating with organic and inorganic compounds, inserting iron oxide into the fiber
and membrane and other porous materials, and combining with activated carbon are
the familiar and useful techniques for protection and improvement of naked iron
oxide. The organic materials like surfactants, polymers, macro-molecules, and biomolecules could physically or chemically passivate the iron oxide nanoparticles.
Oleic acid as a surfactant uses the chemical precipitation to coat the ferrite. The –
COOH group of oleic acid reacts with the Fe atoms and its hydrophobic tail
fabricates a nonpolar coat. The sorption efficiency of oleic molecule-Fe 3 O 4 hybrid
nanomaterials was reported at about 95 wt% for crude oil. The appropriate surface
area, density, and chemical stability make the polymeric materials excellent coating
materials. The rich functional group of polymer is connected to iron oxide
nanoparticles by ligand exchange reaction. According to reported literature, polymer
coated with polyvinylpyrrolidone could adsorb oil 100%. The starch, chitosan, and
alginic acid are the common macromolecules that are used to modify iron oxide due
to their biodegradability, high stability in various pHs, and nontoxicity. Moreover,
the protein as biomolecule has good performance in ferrite modification. Nevertheless, the organic coating materials have some disadvantages like leaching by acidic
solution, low intrinsic stability at higher temperature, and negative effect of thick
shell on the saturation magnetization.
Inorganic materials such as silica, metal oxide, and carbon were used to improve
the stability of uncovered iron oxide nanoparticles. The carbon covered iron oxide
enhances the chemical and thermal stability of modified iron oxide. The water angle
contact of carbon-coated magnetic nanoparticles was reported near
superhydrophobic structure (> 150
). But silica-coated magnetic nanoparticles
have a significant sorption capacity and reusability. The inorganic-coated iron
oxide nanoparticles processes have not been developed and understood completely.
As mentioned in Sect. 1.5.2.1, electrospinning is a facile method to produce
nanofibers, especially magnetic nanofibers like polystyrene/Fe 3 O 4 , polyvinyl alcohol/Fe 3 O 4 , polyacrylonitrile/Fe 3 O 4 , and polyvinyl pyrrolidone/Fe 3 O 4 . High
oleophilicity, selective adsorption, quick removal, and high saturation magnetization
value are the advantages of this type of nanofibers. Other porous sorbents like
aerogels, foams, and sponges can be modified by magnetic nanoparticles to achieve
higher sorption capacity and easy collection.
Activated carbon is applied as inorganic oil sorbent due to its high specific surface
area and porosity. The magnetic activated carbon has the desirable benefits of
activated carbon and the magnetic property of magnetic materials (Qiao et al.
2019). Table 12.10 presents the summary of magnetic sorbents’ properties and
their sorption capacities. Although there are many different methods to fabricate
magnetic sorbents, still this field needs more investigation.
Zhu et al. (2010) used a thermal decomposition method to coat
Fe 3 O 4 nanoparticles with a carbon layer and modified the surface of as-prepared
nanoparticles with polysiloxane layers to achieve superhydrophobic and
436
M. Fatehi et al.
makes them appropriate for grafting these nanoparticles to other oilsorbents for easy
and quick reusability after sorption. Then ultrasonic washing treatment was used as
reuse method and indicated the reusability of magnetic sorbents.
Coating with organic and inorganic compounds, inserting iron oxide into the fiber
and membrane and other porous materials, and combining with activated carbon are
the familiar and useful techniques for protection and improvement of naked iron
oxide. The organic materials like surfactants, polymers, macro-molecules, and biomolecules could physically or chemically passivate the iron oxide nanoparticles.
Oleic acid as a surfactant uses the chemical precipitation to coat the ferrite. The –
COOH group of oleic acid reacts with the Fe atoms and its hydrophobic tail
fabricates a nonpolar coat. The sorption efficiency of oleic molecule-Fe 3 O 4 hybrid
nanomaterials was reported at about 95 wt% for crude oil. The appropriate surface
area, density, and chemical stability make the polymeric materials excellent coating
materials. The rich functional group of polymer is connected to iron oxide
nanoparticles by ligand exchange reaction. According to reported literature, polymer
coated with polyvinylpyrrolidone could adsorb oil 100%. The starch, chitosan, and
alginic acid are the common macromolecules that are used to modify iron oxide due
to their biodegradability, high stability in various pHs, and nontoxicity. Moreover,
the protein as biomolecule has good performance in ferrite modification. Nevertheless, the organic coating materials have some disadvantages like leaching by acidic
solution, low intrinsic stability at higher temperature, and negative effect of thick
shell on the saturation magnetization.
Inorganic materials such as silica, metal oxide, and carbon were used to improve
the stability of uncovered iron oxide nanoparticles. The carbon covered iron oxide
enhances the chemical and thermal stability of modified iron oxide. The water angle
contact of carbon-coated magnetic nanoparticles was reported near
superhydrophobic structure (> 150
). But silica-coated magnetic nanoparticles
have a significant sorption capacity and reusability. The inorganic-coated iron
oxide nanoparticles processes have not been developed and understood completely.
As mentioned in Sect. 1.5.2.1, electrospinning is a facile method to produce
nanofibers, especially magnetic nanofibers like polystyrene/Fe 3 O 4 , polyvinyl alcohol/Fe 3 O 4 , polyacrylonitrile/Fe 3 O 4 , and polyvinyl pyrrolidone/Fe 3 O 4 . High
oleophilicity, selective adsorption, quick removal, and high saturation magnetization
value are the advantages of this type of nanofibers. Other porous sorbents like
aerogels, foams, and sponges can be modified by magnetic nanoparticles to achieve
higher sorption capacity and easy collection.
Activated carbon is applied as inorganic oil sorbent due to its high specific surface
area and porosity. The magnetic activated carbon has the desirable benefits of
activated carbon and the magnetic property of magnetic materials (Qiao et al.
2019). Table 12.10 presents the summary of magnetic sorbents’ properties and
their sorption capacities. Although there are many different methods to fabricate
magnetic sorbents, still this field needs more investigation.
Zhu et al. (2010) used a thermal decomposition method to coat
Fe 3 O 4 nanoparticles with a carbon layer and modified the surface of as-prepared
nanoparticles with polysiloxane layers to achieve superhydrophobic and
436
M. Fatehi et al.