3.3 Waste Water Decontamination by Metal Oxide
Nanomaterials
Development of nanotechnology in the field of waste water decontamination continuously emerges as one of important area of research. The main pollutants namely
toxic metal ions, organic pollutants and microorganisms in water treatment process
can be removed by different nanomaterials in particular by metal oxide
nanomaterials. Recently, metal oxide nanomaterials are on its way to develop an
efficient and economical reagent to clean the waste water pollutants (Fei and Li
2010). Remediation of water by metal-oxide nanomaterials is due to their variable
properties and stable valences, high surface area and variable electronic configuration. This chapter includes the current advances on the use of metal-oxide based
nanomaterials (TiO 2 , Fe 2 O 3 , ZnO, CeO 2 and Al 2 O 3 ) in waste water decontamination. Some of the important metal oxide nanomaterials and their derivatives as
adsorbents have been discussed below with the improving adsorbent properties in
detail.
3.3.1 Titanium Dioxide (TiO 2 ) Nanomaterials
Titanium dioxide (TiO 2 ) is one of the important and widely used photocatalyst for
water treatment (Nolan et al. 2009; Hu et al. 2013; Oh et al. 2003). Titanium dioxide
is important decontaminating agent for the degradation and removal of organic dyes
and other organic contaminants because of its high photo-catalytic activity, cheap,
non-toxicity and high stability (Zhou et al. 2011; Akpan and Hameed 2009; LydakisSimantiris et al. 2010; Shinde et al. 2017). Among the three different polymorph
anatase, rutile, and brookite, the Degussa P- 25 photocatalyst (mixture of anatase and
rutile titanium dioxide) exhibited high photocatalytic activity for the degradation of
organic dyes compared to other forms of titanium dioxide, uses commercially (Zhou
et al. 2012a, b; Hou et al. 2015). Titanium dioxide nanoparticles exhibits low
selectivity and are able to degrade various pollutants, like chlorinated compounds
(Ohsaka et al. 2008), polycyclic aromatic hydrocarbons (Guo et al. 2015), dyes (Lee
et al. 2008), phenolic compounds (Nguyen et al. 2016), pesticides (Alalm et al.
2015), arsenic (Moon et al. 2014), cyanide (Kim et al. 2016), and heavy metals
(Chen and Guoetal 2016).
Recently, efficiency of photocatalytic activity of titanium dioxide nanomaterials
for waste water treatment is continuously improving either by modifying the morphology with increase in surface area and porosity or by modifying chemically with
the incorporation of various semiconductor, doping of metal ion/non-metal ion
(Jiang et al. 2006), co-doping with foreign ion (Li et al. 2012) and noble metal
deposition and combination with electron acceptor materials (Pelaez et al. 2012).
Degradation of phenol is achieved by Fe(III)-doped titanium dioxide nanoparticles
under solar light irradiation (Nahar et al. 2006). Noble metals like Ag, Au, Pt and Pd
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M. Tauqeer et al.
Nanomaterials
Development of nanotechnology in the field of waste water decontamination continuously emerges as one of important area of research. The main pollutants namely
toxic metal ions, organic pollutants and microorganisms in water treatment process
can be removed by different nanomaterials in particular by metal oxide
nanomaterials. Recently, metal oxide nanomaterials are on its way to develop an
efficient and economical reagent to clean the waste water pollutants (Fei and Li
2010). Remediation of water by metal-oxide nanomaterials is due to their variable
properties and stable valences, high surface area and variable electronic configuration. This chapter includes the current advances on the use of metal-oxide based
nanomaterials (TiO 2 , Fe 2 O 3 , ZnO, CeO 2 and Al 2 O 3 ) in waste water decontamination. Some of the important metal oxide nanomaterials and their derivatives as
adsorbents have been discussed below with the improving adsorbent properties in
detail.
3.3.1 Titanium Dioxide (TiO 2 ) Nanomaterials
Titanium dioxide (TiO 2 ) is one of the important and widely used photocatalyst for
water treatment (Nolan et al. 2009; Hu et al. 2013; Oh et al. 2003). Titanium dioxide
is important decontaminating agent for the degradation and removal of organic dyes
and other organic contaminants because of its high photo-catalytic activity, cheap,
non-toxicity and high stability (Zhou et al. 2011; Akpan and Hameed 2009; LydakisSimantiris et al. 2010; Shinde et al. 2017). Among the three different polymorph
anatase, rutile, and brookite, the Degussa P- 25 photocatalyst (mixture of anatase and
rutile titanium dioxide) exhibited high photocatalytic activity for the degradation of
organic dyes compared to other forms of titanium dioxide, uses commercially (Zhou
et al. 2012a, b; Hou et al. 2015). Titanium dioxide nanoparticles exhibits low
selectivity and are able to degrade various pollutants, like chlorinated compounds
(Ohsaka et al. 2008), polycyclic aromatic hydrocarbons (Guo et al. 2015), dyes (Lee
et al. 2008), phenolic compounds (Nguyen et al. 2016), pesticides (Alalm et al.
2015), arsenic (Moon et al. 2014), cyanide (Kim et al. 2016), and heavy metals
(Chen and Guoetal 2016).
Recently, efficiency of photocatalytic activity of titanium dioxide nanomaterials
for waste water treatment is continuously improving either by modifying the morphology with increase in surface area and porosity or by modifying chemically with
the incorporation of various semiconductor, doping of metal ion/non-metal ion
(Jiang et al. 2006), co-doping with foreign ion (Li et al. 2012) and noble metal
deposition and combination with electron acceptor materials (Pelaez et al. 2012).
Degradation of phenol is achieved by Fe(III)-doped titanium dioxide nanoparticles
under solar light irradiation (Nahar et al. 2006). Noble metals like Ag, Au, Pt and Pd
70
M. Tauqeer et al.