the importance and possible scope of upgrading the conventional arsenic treatment
systems with newly developed nanoadsorbets are reviewed, and might be considered
for future application in real-world scenario (Kumar et al. 2020).
2.6
Scope of Nanotechnology-Based Treatment Systems
The above-mentioned removal methods have been reported to have the
disadvantages in terms of generating highly toxic waste that causes its easy mobilization in the living ecosystems. Arsenic removal through coagulation/flocculation
requires addition of chemicals and thereafter removal in the form of precipitates after
the completion of process. This serves as one of the drawbacks of this technology.
Also, there are the possibilities of generation of secondary pollutants in treated
water, which may cause diseases related to these pollutants. Moreover, the
technologies such as ion-exchange and membrane processes have limitations in
terms of their higher energy consumption, higher costs and complex removal
mechanisms.
Among the above-mentioned removal methods, arsenic removal by adsorption
has still gained considerable attention even considering its limitation in handling
toxic waste after the exhaustion of adsorbed material. It is widely acceptable
technology as on today due to its easy operation, less maintenance cost and costeffectiveness (Grassi et al. 2012). The literature is widely replete in cases of
development of different nanoadsorbents, which have been explored for arsenic
removal (Lata and Samadder 2016). From the past two decades, several metallic
nanoadsorbents, including oxides of iron, aluminium, cerium, copper, zirconium and
titanium, have been reported to developed for arsenic removal (Ali 2012). Metallic
iron-based nanoadsorbents have been widely explored due to their strong affinity
towards arsenic and ecological-friendly nature. Therefore, the development of its
polymorphs, such as nZVI, iron
III oxides (α-Fe 2 O 3 , β- Fe 2 O 3 , γ- Fe 2 O 3 ), iron
III (oxy)
hydroxides (α-FeOOH, β-FeOOH, γ-FeOOH) and iron
II,III oxides (magnetite), are
being reported in literature for arsenic removal. Among these, nZVI (nanoscale zerovalent iron) has been extensively explored in the literature both at laboratory- and
pilot-scale studies. These nanoparticles are unstable in natural environmental
conditions and prone to oxidize into iron oxides/hydroxides after oxidation which
limit its application for pilot-scale studies significantly (Nurmi et al. 2005).
The literature is also replete in providing a number of adsorbents for arsenic
removal in groundwater, which involve the use of naturally originated, synthetic
adsorbent materials and low cost materials (Zhang and Selim 2005; Genc-Fuhrman
et al. 2004; Gu et al. 2005; Elizalde-Gonzalez et al. 2001; Gillman 2006; Malik et al.
2009; Sullivan et al. 1997). In recent years, a number of nanoadsorbents, such as
nZVI alone (Yin et al. 2012) supported on clay, tea waste, polyaniline and starch
(Tandon et al. 2013; Bhaumik et al. 2014; Mosaferi et al. 2014); oxides of iron
(De et al. 2009; Wang et al. 2011; Lin et al. 2014); titania as anatase (Özlem
Kocabaş-Atakli and Yürüm 2013; Danish et al. 2013); cerium (IV) oxide (Sun
et al. 2012); copper (Reddy et al. 2013); and polymer-based adsorbents (Davodi
2 Nanotechnology-Based Treatment Systems for Arsenic Sequestration in. . .
43
systems with newly developed nanoadsorbets are reviewed, and might be considered
for future application in real-world scenario (Kumar et al. 2020).
2.6
Scope of Nanotechnology-Based Treatment Systems
The above-mentioned removal methods have been reported to have the
disadvantages in terms of generating highly toxic waste that causes its easy mobilization in the living ecosystems. Arsenic removal through coagulation/flocculation
requires addition of chemicals and thereafter removal in the form of precipitates after
the completion of process. This serves as one of the drawbacks of this technology.
Also, there are the possibilities of generation of secondary pollutants in treated
water, which may cause diseases related to these pollutants. Moreover, the
technologies such as ion-exchange and membrane processes have limitations in
terms of their higher energy consumption, higher costs and complex removal
mechanisms.
Among the above-mentioned removal methods, arsenic removal by adsorption
has still gained considerable attention even considering its limitation in handling
toxic waste after the exhaustion of adsorbed material. It is widely acceptable
technology as on today due to its easy operation, less maintenance cost and costeffectiveness (Grassi et al. 2012). The literature is widely replete in cases of
development of different nanoadsorbents, which have been explored for arsenic
removal (Lata and Samadder 2016). From the past two decades, several metallic
nanoadsorbents, including oxides of iron, aluminium, cerium, copper, zirconium and
titanium, have been reported to developed for arsenic removal (Ali 2012). Metallic
iron-based nanoadsorbents have been widely explored due to their strong affinity
towards arsenic and ecological-friendly nature. Therefore, the development of its
polymorphs, such as nZVI, iron
III oxides (α-Fe 2 O 3 , β- Fe 2 O 3 , γ- Fe 2 O 3 ), iron
III (oxy)
hydroxides (α-FeOOH, β-FeOOH, γ-FeOOH) and iron
II,III oxides (magnetite), are
being reported in literature for arsenic removal. Among these, nZVI (nanoscale zerovalent iron) has been extensively explored in the literature both at laboratory- and
pilot-scale studies. These nanoparticles are unstable in natural environmental
conditions and prone to oxidize into iron oxides/hydroxides after oxidation which
limit its application for pilot-scale studies significantly (Nurmi et al. 2005).
The literature is also replete in providing a number of adsorbents for arsenic
removal in groundwater, which involve the use of naturally originated, synthetic
adsorbent materials and low cost materials (Zhang and Selim 2005; Genc-Fuhrman
et al. 2004; Gu et al. 2005; Elizalde-Gonzalez et al. 2001; Gillman 2006; Malik et al.
2009; Sullivan et al. 1997). In recent years, a number of nanoadsorbents, such as
nZVI alone (Yin et al. 2012) supported on clay, tea waste, polyaniline and starch
(Tandon et al. 2013; Bhaumik et al. 2014; Mosaferi et al. 2014); oxides of iron
(De et al. 2009; Wang et al. 2011; Lin et al. 2014); titania as anatase (Özlem
Kocabaş-Atakli and Yürüm 2013; Danish et al. 2013); cerium (IV) oxide (Sun
et al. 2012); copper (Reddy et al. 2013); and polymer-based adsorbents (Davodi
2 Nanotechnology-Based Treatment Systems for Arsenic Sequestration in. . .
43