Composites Containing Inorganic Ion Exchangers …
105
water. Silica-grafted GO demonstrates selectivity toward Pb
2+ [48]. The materials
containing heteropolyacids can be recommended for recovery of NH 4
+ ions [53].
The information regarding adsorption of heavy metal ions on GO and its
composites is summarized in [40, 74].
5 Adsorption of Organic Species
Hydrophobic regions of GO sheets provide adsorption of organic compounds on
the composites containing this carbon material. Despite depressed anion exchange
properties, the composite adsorbs phenol that is a weak acids [15]. When the initial
concentration of this compound is 5 mg dm
−3 , the composite based on hydrated
zirconium oxide removes it down to maximal allowable concentration for tap water
(1 μg dm
−3 ). In the case of pure inorganic ion exchanger, adsorption of phenol
is inconsiderable. Adsorption of p-cresol and p-tert-butylphenol on the composite
containing manganese oxide is accompanied by their oxidation [81]. The support,
which contains variable valence metal, is more effective compared with MnO 2 .
A number of works are devoted to adsorption of cationic dyes on composites,
for instance, Methylene Blue [39, 51, 82–84] or Malachite Green [44]. Adsorption
of anionic dyes, such as Congo Red [79, 85], Methyl Orange [79], and Eriochrome
Black T [44] on oxide-based materials, was also studied. It is stressed that electrostatic
attraction is dominating adsorption mechanism, which is strongly dependent on the
solution pH. When photocatalytic materials are used as a support, the dye adsorption
is accompanied by degradation [82]. Good photocatalytic performance of the TiO 2 –
GO composite could be attributed to a synergy effect including the increase in specific
surface area with GO amount as well as the formation of both π–π conjugations
between dye molecules and aromatic rings, and the interactions between the molecule
and functional groups of GO. This carbon material works as the adsorbent, electron
acceptor, and photosensitizer to efficiently enhance the dye photodecomposition.
The composites are also effective toward molecular substances: lactose [15],
aromatic compounds [49], such antibiotic as tetracycline [42, 43], and hormones
[41]. In the case of lactose removal from water using the composite based on hydrated
zirconium oxide, it is possible to reach the COD value that is lower than the maximal
allowable concentration for tap water (5 mg dm
−3 ) [15]. Conversely, pure zirconium
oxide shows no lactose adsorption. The material based on metal–organic framework
has been proposed for acetone adsorption [52].
The GO-Fe 3 O 4 nanocomposite has been tested against Gram-positive and Gramnegative bacterial strains including Staphylococcus aureus, Bacillus subtilis, Pseudomonas aerugino, and Salmonella typhimuriumupon [44]. As shown, the composite
demonstrates promising antimicrobial activity.
105
water. Silica-grafted GO demonstrates selectivity toward Pb
2+ [48]. The materials
containing heteropolyacids can be recommended for recovery of NH 4
+ ions [53].
The information regarding adsorption of heavy metal ions on GO and its
composites is summarized in [40, 74].
5 Adsorption of Organic Species
Hydrophobic regions of GO sheets provide adsorption of organic compounds on
the composites containing this carbon material. Despite depressed anion exchange
properties, the composite adsorbs phenol that is a weak acids [15]. When the initial
concentration of this compound is 5 mg dm
−3 , the composite based on hydrated
zirconium oxide removes it down to maximal allowable concentration for tap water
(1 μg dm
−3 ). In the case of pure inorganic ion exchanger, adsorption of phenol
is inconsiderable. Adsorption of p-cresol and p-tert-butylphenol on the composite
containing manganese oxide is accompanied by their oxidation [81]. The support,
which contains variable valence metal, is more effective compared with MnO 2 .
A number of works are devoted to adsorption of cationic dyes on composites,
for instance, Methylene Blue [39, 51, 82–84] or Malachite Green [44]. Adsorption
of anionic dyes, such as Congo Red [79, 85], Methyl Orange [79], and Eriochrome
Black T [44] on oxide-based materials, was also studied. It is stressed that electrostatic
attraction is dominating adsorption mechanism, which is strongly dependent on the
solution pH. When photocatalytic materials are used as a support, the dye adsorption
is accompanied by degradation [82]. Good photocatalytic performance of the TiO 2 –
GO composite could be attributed to a synergy effect including the increase in specific
surface area with GO amount as well as the formation of both π–π conjugations
between dye molecules and aromatic rings, and the interactions between the molecule
and functional groups of GO. This carbon material works as the adsorbent, electron
acceptor, and photosensitizer to efficiently enhance the dye photodecomposition.
The composites are also effective toward molecular substances: lactose [15],
aromatic compounds [49], such antibiotic as tetracycline [42, 43], and hormones
[41]. In the case of lactose removal from water using the composite based on hydrated
zirconium oxide, it is possible to reach the COD value that is lower than the maximal
allowable concentration for tap water (5 mg dm
−3 ) [15]. Conversely, pure zirconium
oxide shows no lactose adsorption. The material based on metal–organic framework
has been proposed for acetone adsorption [52].
The GO-Fe 3 O 4 nanocomposite has been tested against Gram-positive and Gramnegative bacterial strains including Staphylococcus aureus, Bacillus subtilis, Pseudomonas aerugino, and Salmonella typhimuriumupon [44]. As shown, the composite
demonstrates promising antimicrobial activity.