98
M. H. Köhler et al.
instance, glutaraldehyde accelerates the cross-linking process between PDA-coated
GO sheets and polyethyleneimine, resulting in a 3D hydrogel that is formed within
only 3 min. This membrane can efficiently adsorb anionic dyes and organic solvents
from water [62]. Also, the addition of 1H, 1H, 2H, 2H-perfluorodecanethiol to the
PDA-rGO structure can create a sponge for water–oil separation [63].
GO/rGO hydro and aerogels containing bacterial cellulose (BC-GO/rGO) have
also been investigated. They can effectively adsorb distinct heavy metals from water,
exhibiting high structural stability [64]. Desorption/readsorption experiments with
BC/GO demonstrated their excellent recyclability [65]. Additionally, these structures have shown underwater superoleophobicity and underoil superhydrophobicity
[66, 67], which is a desirable characteristic for the removal of oils and organic
solvents from water. Cellulose acetate nanofibers can be employed to prevent
GO nanosheets from self-assembly after reduction. This increases the connectivity
between nanopores, creating aerogels able to retain oils and organic dyes [68].
The combination of different reducing agents can lead to unique properties. For
instance, a specific adsorbent agent is able to remove either cationic or anionic dyes.
However, combining GO with polyvinyl alcohol and using L-cysteine as the reducing
agent makes an ultralight aerogel that is able to absorb both species [69], increasing
the membrane’s scope.
Chitosan is a biopolymer extensively employed to functionalize 3D-GO/rGO
hydro and aerogels, leading to materials with high adsorption of heavy metals,
neutral and charged dyes, and oils [70–72]. Additionally, GO, chitosan, and cellulose composites can be combined to create porous nanospheres. These structures
have been used as an alternative for removing heavy metals from water solutions and
even directly from the soil, which broadens their use in environmental treatments
[73, 74]. Also, chitosan and activated carbon-functionalized GO flakes have demonstrated promising removal of pharmaceuticals and personal care products from water
[75].
The combination of GO/rGO with other biopolymers also leads to interesting
adsorption properties. GO/silk fibroin hybrid aerogel has been designed for dye and
heavy metal adsorption [76], while carbon nanofiber/GO composite aerogels were
used in highly efficient oil absorption prototypes [77].
The hydrothermal polymerization of lignin and sodium alginate (SA) in the presence of GO in an aqueous system was used to create a hydrogel with high adsorption of heavy metals [78]. On the other hand, SA/rGO composite hydrogel crosslinked by Fe
3+ exhibited an improved dye adsorption performance [79], especially
for cationic dyes. The efficient removal is achieved due to a synergetic interaction
between GO/rGO and SA. Another advantage of SA is to create 3D printable and
mechanically robust hydrogels, as recently obtained from a GO and amino-GO (aGO)
non-covalently functionalized with SA [80].
The functionalization is not restricted to carbon-based molecules. Many other
materials can be used to get improved properties. Cadmium sulfide (CdS)functionalized aerogels showed an enhanced absorption of ionic dyes [81], while
adding iron nanoparticles to GO hydrogels make it highly efficient to remove organic
pollutants [82]. N-doped rGO aerogels showed excellent catalytic degradation of
M. H. Köhler et al.
instance, glutaraldehyde accelerates the cross-linking process between PDA-coated
GO sheets and polyethyleneimine, resulting in a 3D hydrogel that is formed within
only 3 min. This membrane can efficiently adsorb anionic dyes and organic solvents
from water [62]. Also, the addition of 1H, 1H, 2H, 2H-perfluorodecanethiol to the
PDA-rGO structure can create a sponge for water–oil separation [63].
GO/rGO hydro and aerogels containing bacterial cellulose (BC-GO/rGO) have
also been investigated. They can effectively adsorb distinct heavy metals from water,
exhibiting high structural stability [64]. Desorption/readsorption experiments with
BC/GO demonstrated their excellent recyclability [65]. Additionally, these structures have shown underwater superoleophobicity and underoil superhydrophobicity
[66, 67], which is a desirable characteristic for the removal of oils and organic
solvents from water. Cellulose acetate nanofibers can be employed to prevent
GO nanosheets from self-assembly after reduction. This increases the connectivity
between nanopores, creating aerogels able to retain oils and organic dyes [68].
The combination of different reducing agents can lead to unique properties. For
instance, a specific adsorbent agent is able to remove either cationic or anionic dyes.
However, combining GO with polyvinyl alcohol and using L-cysteine as the reducing
agent makes an ultralight aerogel that is able to absorb both species [69], increasing
the membrane’s scope.
Chitosan is a biopolymer extensively employed to functionalize 3D-GO/rGO
hydro and aerogels, leading to materials with high adsorption of heavy metals,
neutral and charged dyes, and oils [70–72]. Additionally, GO, chitosan, and cellulose composites can be combined to create porous nanospheres. These structures
have been used as an alternative for removing heavy metals from water solutions and
even directly from the soil, which broadens their use in environmental treatments
[73, 74]. Also, chitosan and activated carbon-functionalized GO flakes have demonstrated promising removal of pharmaceuticals and personal care products from water
[75].
The combination of GO/rGO with other biopolymers also leads to interesting
adsorption properties. GO/silk fibroin hybrid aerogel has been designed for dye and
heavy metal adsorption [76], while carbon nanofiber/GO composite aerogels were
used in highly efficient oil absorption prototypes [77].
The hydrothermal polymerization of lignin and sodium alginate (SA) in the presence of GO in an aqueous system was used to create a hydrogel with high adsorption of heavy metals [78]. On the other hand, SA/rGO composite hydrogel crosslinked by Fe
3+ exhibited an improved dye adsorption performance [79], especially
for cationic dyes. The efficient removal is achieved due to a synergetic interaction
between GO/rGO and SA. Another advantage of SA is to create 3D printable and
mechanically robust hydrogels, as recently obtained from a GO and amino-GO (aGO)
non-covalently functionalized with SA [80].
The functionalization is not restricted to carbon-based molecules. Many other
materials can be used to get improved properties. Cadmium sulfide (CdS)functionalized aerogels showed an enhanced absorption of ionic dyes [81], while
adding iron nanoparticles to GO hydrogels make it highly efficient to remove organic
pollutants [82]. N-doped rGO aerogels showed excellent catalytic degradation of