definite dimension and geometry. Porous silica nanostructures might be classified on
the basis of the shape and size of their pores. Silica nanoparticles with pore sizes
ranging from 2 to 5 nm are regarded as 2D hexagonal p6m (MCM-41), 3D cubic
Ia3d (MCM-48), and lamellar p2 (MCM-50) (Fig. 18.1b and c). Silicas with larger
pore sizes, i.e., in the range of 6 to 20 nm, are called SBA-15, and the shape
specification of their pores is 2D-hexagonal-p6mm. Additional 3D cubic silicas
with even larger pores are also known, such as IBN-2 (Fm3m) (Han and Ying 2005).
During the past few years, significant attention has been paid to the use of
MCM-41 to trap some volatile organic moieties via physisorption or chemisorption
after structural and compositional modifications. It has also been effectively
employed to confiscate toxic heavy metals and dissolve dyes from polluted water
(Yoshitake et al. 2003). Functionalization of silicas with organic functional groups,
such as amino, malonamide, imidazole, carbonyl, carboxyl, humic acid, and dithiocarbamate, can lead to a material having a much improved capacity for the degradation of aqueous dyes. In comparison with MCM-41, SBA-15 possesses bigger
pores with a tunable size that permits targeted pollutants to easily access the inner
surface of the nanoparticles. This leads to swift kinetics and non-equilibrium adsorption, and SBA-15 exhibits improved ability of adsorption than MCM-41. Furthermore, the ultrathin (around 4 nm) pore walls provide remarkable mechanical
stability. Even though such materials behave as promising adsorbents, as compared
with other conventional absorbents, such as active carbon, the lack of surface
functionalities greatly limits their adsorption utilizations, particularly in case of
high adsorption selectivity and capacity. This limitation can be overcome simply
by chemical modification of its surface. Surface modifications have been achieved
by using dodecylamine, tetrakis(4-carboxyphenyl)porphyrin, 2-mercaptopyridine,
and 3-aminopropyltrimethoxy silane. These surface-modified mesoporous silicas
were than employed to eliminate dyes and toxic heavy metal species from wastewater (Benhamou et al. 2013; Davarpanah and Kiasat 2014; Pérez-Quintanilla et al.
2006).
18.2.2 Iron-Based Magnetic Materials
The ability of nanomaterials to recycle carbon coated Fe3O4 nanoparticles must be
considered while choosing the best agent to treat wastewater from textile industries.
Magnetism helps in water purification by effecting the physical characteristics of
contaminants. Best adsorption ability along with easy magnetic separation has been
widely employed in the treatment of wastewater and environmental remediation.
During the past few years, magnetic iron oxide nanomaterials have been extensively
investigated in large-scale treatment of wastewater owing to their enhanced adsorption capability, easy recyclability, and superior stability (Xu et al. 2012). The use of
Fe 3 O 4 materials in both lab scale and industrial scale has revealed that such magnetic
responsive nanomaterials possess more improved ability to treat huge quantities of
effluents discharged from a textile industry than carbon-based materials and atomic
18 Nanomaterials for Textile Waste Treatment
667
the basis of the shape and size of their pores. Silica nanoparticles with pore sizes
ranging from 2 to 5 nm are regarded as 2D hexagonal p6m (MCM-41), 3D cubic
Ia3d (MCM-48), and lamellar p2 (MCM-50) (Fig. 18.1b and c). Silicas with larger
pore sizes, i.e., in the range of 6 to 20 nm, are called SBA-15, and the shape
specification of their pores is 2D-hexagonal-p6mm. Additional 3D cubic silicas
with even larger pores are also known, such as IBN-2 (Fm3m) (Han and Ying 2005).
During the past few years, significant attention has been paid to the use of
MCM-41 to trap some volatile organic moieties via physisorption or chemisorption
after structural and compositional modifications. It has also been effectively
employed to confiscate toxic heavy metals and dissolve dyes from polluted water
(Yoshitake et al. 2003). Functionalization of silicas with organic functional groups,
such as amino, malonamide, imidazole, carbonyl, carboxyl, humic acid, and dithiocarbamate, can lead to a material having a much improved capacity for the degradation of aqueous dyes. In comparison with MCM-41, SBA-15 possesses bigger
pores with a tunable size that permits targeted pollutants to easily access the inner
surface of the nanoparticles. This leads to swift kinetics and non-equilibrium adsorption, and SBA-15 exhibits improved ability of adsorption than MCM-41. Furthermore, the ultrathin (around 4 nm) pore walls provide remarkable mechanical
stability. Even though such materials behave as promising adsorbents, as compared
with other conventional absorbents, such as active carbon, the lack of surface
functionalities greatly limits their adsorption utilizations, particularly in case of
high adsorption selectivity and capacity. This limitation can be overcome simply
by chemical modification of its surface. Surface modifications have been achieved
by using dodecylamine, tetrakis(4-carboxyphenyl)porphyrin, 2-mercaptopyridine,
and 3-aminopropyltrimethoxy silane. These surface-modified mesoporous silicas
were than employed to eliminate dyes and toxic heavy metal species from wastewater (Benhamou et al. 2013; Davarpanah and Kiasat 2014; Pérez-Quintanilla et al.
2006).
18.2.2 Iron-Based Magnetic Materials
The ability of nanomaterials to recycle carbon coated Fe3O4 nanoparticles must be
considered while choosing the best agent to treat wastewater from textile industries.
Magnetism helps in water purification by effecting the physical characteristics of
contaminants. Best adsorption ability along with easy magnetic separation has been
widely employed in the treatment of wastewater and environmental remediation.
During the past few years, magnetic iron oxide nanomaterials have been extensively
investigated in large-scale treatment of wastewater owing to their enhanced adsorption capability, easy recyclability, and superior stability (Xu et al. 2012). The use of
Fe 3 O 4 materials in both lab scale and industrial scale has revealed that such magnetic
responsive nanomaterials possess more improved ability to treat huge quantities of
effluents discharged from a textile industry than carbon-based materials and atomic
18 Nanomaterials for Textile Waste Treatment
667