3.2 Metal Based Nanomaterials in Water Treatment
Modernization and industrialization cause serious and harmful effect on human
society mainly by contaminating the water. Different pollutants used for the contamination are heavy metal ions like Pb
2+ , Cd
2+ , Zn
2+ , Ni
2+ and Hg
2 , organic
compounds like, phenols, dyes, benzene and bacteria, viruses, and so on. These
pollutants are mostly eliminated by adsorption technology because of its low cost,
high efficiency, and easy removal of pollutants. To enhance the absorption process,
improvement in adsorption capacity of nanomaterials is taken into consideration by
using various doping phenomenon which ultimately are used to remove various
contaminants from wastewater. Metal based nanomaterials emerge as one of the
beneficial agents for the effective waste water decontamination of pollutants. This
part briefly explains different types of metal based nano adsorbents mainly gold
nanomaterials, silver nanomaterials, iron nanomaterials, palladium nanomaterial,
platinum nanomaterials and zinc nanomaterials along with their hybrid adsorbents
for the decontamination of various pollutants.
3.2.1 Gold (Au) Based Nanomaterials
Among the various metal-based nanomaterials, gold nanomaterials are one of the most
widely used nanomaterials for the decontamination of different pollutant from waste
water (Tiwari and Paul 2015; Pantapasis and Grumezescu 2017). Interest in gold
nanoparticles (AuNPs) to be used as nanoprobes for the different pollutants like heavy
metals, organic pollutants and other pathogenic pollutants is continuously increasing
because of their high selectivity and high binding capacity (Koedrith et al. 2015;
Tamer et al. 2013). Jimoh et al. (2015) reported the selectivity for iron ion (Fe
3+
)
using nanogold-Schiff base chemosensor (l-thiolated Schiff base coating on gold
nanoparticles) in a mixture of water. Determination of cobalt ion (Co
2+
) in aqueous
solution is achieved using gold nanoparticles stabilized with S 2 O 3
2À and
ethylenediamine (en) (Zhang et al. 2012a, b).
Gold nanomaterials for the decontamination of organic compounds are important
because of high toxicity of organic pollutants which affects the human badly.
Phenols are considered to be the most toxic organic contaminants in the environments (CDC 2011). Gold nanoparticles is used to reduce the p-nitrophenol to
4-aminophenol by excess of borohydride (Lin et al. 2013) and another study
(Lerma-García et al. 2014) uses Au/Al 2 O 3 for this reduction in presence of NaBH 4 .
Gold nanoparticles (AuNPs) are known to exhibit good antibacterial effect
against both gram positive and gram-negative bacteria. As we have seen in literature
the biosynthesized gold nanoparticles are found to inhibit the growth of
Staphylococcus aureus, Basilus subtilus and E.coli (Khan et al. 2016). Without
external excitations, amine-functionalized gold and titanium dioxide nanoparticles
have shown excellent antibacterial excellent antibacterial effect for waste water
66
M. Tauqeer et al.
Modernization and industrialization cause serious and harmful effect on human
society mainly by contaminating the water. Different pollutants used for the contamination are heavy metal ions like Pb
2+ , Cd
2+ , Zn
2+ , Ni
2+ and Hg
2 , organic
compounds like, phenols, dyes, benzene and bacteria, viruses, and so on. These
pollutants are mostly eliminated by adsorption technology because of its low cost,
high efficiency, and easy removal of pollutants. To enhance the absorption process,
improvement in adsorption capacity of nanomaterials is taken into consideration by
using various doping phenomenon which ultimately are used to remove various
contaminants from wastewater. Metal based nanomaterials emerge as one of the
beneficial agents for the effective waste water decontamination of pollutants. This
part briefly explains different types of metal based nano adsorbents mainly gold
nanomaterials, silver nanomaterials, iron nanomaterials, palladium nanomaterial,
platinum nanomaterials and zinc nanomaterials along with their hybrid adsorbents
for the decontamination of various pollutants.
3.2.1 Gold (Au) Based Nanomaterials
Among the various metal-based nanomaterials, gold nanomaterials are one of the most
widely used nanomaterials for the decontamination of different pollutant from waste
water (Tiwari and Paul 2015; Pantapasis and Grumezescu 2017). Interest in gold
nanoparticles (AuNPs) to be used as nanoprobes for the different pollutants like heavy
metals, organic pollutants and other pathogenic pollutants is continuously increasing
because of their high selectivity and high binding capacity (Koedrith et al. 2015;
Tamer et al. 2013). Jimoh et al. (2015) reported the selectivity for iron ion (Fe
3+
)
using nanogold-Schiff base chemosensor (l-thiolated Schiff base coating on gold
nanoparticles) in a mixture of water. Determination of cobalt ion (Co
2+
) in aqueous
solution is achieved using gold nanoparticles stabilized with S 2 O 3
2À and
ethylenediamine (en) (Zhang et al. 2012a, b).
Gold nanomaterials for the decontamination of organic compounds are important
because of high toxicity of organic pollutants which affects the human badly.
Phenols are considered to be the most toxic organic contaminants in the environments (CDC 2011). Gold nanoparticles is used to reduce the p-nitrophenol to
4-aminophenol by excess of borohydride (Lin et al. 2013) and another study
(Lerma-García et al. 2014) uses Au/Al 2 O 3 for this reduction in presence of NaBH 4 .
Gold nanoparticles (AuNPs) are known to exhibit good antibacterial effect
against both gram positive and gram-negative bacteria. As we have seen in literature
the biosynthesized gold nanoparticles are found to inhibit the growth of
Staphylococcus aureus, Basilus subtilus and E.coli (Khan et al. 2016). Without
external excitations, amine-functionalized gold and titanium dioxide nanoparticles
have shown excellent antibacterial excellent antibacterial effect for waste water
66
M. Tauqeer et al.