300
11.4.6 Composites, Nanocomposites,
and Miscellaneous Adsorbents
Composites and nanocomposites are defined as inclusions in the matrix; they consist of two phases (dispersed and scattering), one of which is dispersed in another
(matrix) thus creating a three-dimensional network. Other interesting materials are
also starch and cyclodextrins. Starches consist of two polyglucans (highly branched
amylopectin, nearly unbranched amylose), and they contain α-d-glucose units
linked together. Starch is frequently used for food applications but due to its abundance, cost, availability in many countries, polyfunctionality, biodegradability, and
adsorptive properties, there is a growing interest in its application for wastewater
treatment. The main drawback of starch is its hydrophilic nature that seriously limits the development of new sorbents based on starch, but its chemical derivatization
results in water-resistant sorbent production (Crini 2006; Raval et al. 2017). Some
examples of above mentioned materials for different type of dyes removal are the
following: methyl green and methylene blue removal by Fe/Ni/Zn/O/polyacrylamide nanocomposite (Kant et al. 2014); methyl green and methylene blue removal
by polyaniline/ZnO nanocomposite (Eskizeybek et al. 2012); methyl green removal
by magnetic Pycnoporus sanguineus-loaded alginate composite beads (Yang et al.
2014); different types of dye removal by cross-linked gels with starch derivatives,
polymers prepared by reticulation of starch-enriched flour, as a cross-linking agent
epichlorohydrin was applied in the presence of NH 4 OH (Delval et al. 2001); dyes
removal by β-cyclodextrin polymers (Crini 2003); and textile dyes removal by gels
of β-cyclodextrin, hydroxypropyl β-cyclodextrin, poly(vinylalcohol) with epichlorohydrin (Shao et al. 1996), etc. More interesting examples of composites, nanocomposites, starch, and cyclodextrin derivates for malachite green and other textile
dyes are collected in review papers (Crini 2006; Raval et al. 2017).
11.4.7 Ion-Exchange Resins
Ion-exchange resins (cation exchangers and anion exchangers) are popular materials for purification of industrial effluents. Ion exchangers reduce the bulk of toxic
load and convert it into a form in which it is less toxic. Very important feature of
ion-exchange reactions is separation and preconcentration of pollutants. Not only
anionic but also cationic resins can be applied for anionic (acid, direct, reactive) and
cationic type dyes (basic dyes), respectively. There are numerous literature reports
on the use of the polystyrene, polyacrylic, and phenol-formaldehyde ion-exchange
resins in the sorption of dyes from both aqueous solutions and wastewater
(Wawrzkiewicz 2010, 2011a, b, 2012a, b, 2013, 2014). Among the commercially
available anion exchangers and cation exchangers, the following resins Lewatit SP
112, Amberlite IRA 67, Amberlite FPA 51, Lewatit MP 62, Amberlyst A 23, Lewatit
MP 64, Lewatit MP 68, Amberlite IRA 478RF, Amberlite IRA 910, Amberlite IRA
A. Wołowicz and M. Wawrzkiewicz
11.4.6 Composites, Nanocomposites,
and Miscellaneous Adsorbents
Composites and nanocomposites are defined as inclusions in the matrix; they consist of two phases (dispersed and scattering), one of which is dispersed in another
(matrix) thus creating a three-dimensional network. Other interesting materials are
also starch and cyclodextrins. Starches consist of two polyglucans (highly branched
amylopectin, nearly unbranched amylose), and they contain α-d-glucose units
linked together. Starch is frequently used for food applications but due to its abundance, cost, availability in many countries, polyfunctionality, biodegradability, and
adsorptive properties, there is a growing interest in its application for wastewater
treatment. The main drawback of starch is its hydrophilic nature that seriously limits the development of new sorbents based on starch, but its chemical derivatization
results in water-resistant sorbent production (Crini 2006; Raval et al. 2017). Some
examples of above mentioned materials for different type of dyes removal are the
following: methyl green and methylene blue removal by Fe/Ni/Zn/O/polyacrylamide nanocomposite (Kant et al. 2014); methyl green and methylene blue removal
by polyaniline/ZnO nanocomposite (Eskizeybek et al. 2012); methyl green removal
by magnetic Pycnoporus sanguineus-loaded alginate composite beads (Yang et al.
2014); different types of dye removal by cross-linked gels with starch derivatives,
polymers prepared by reticulation of starch-enriched flour, as a cross-linking agent
epichlorohydrin was applied in the presence of NH 4 OH (Delval et al. 2001); dyes
removal by β-cyclodextrin polymers (Crini 2003); and textile dyes removal by gels
of β-cyclodextrin, hydroxypropyl β-cyclodextrin, poly(vinylalcohol) with epichlorohydrin (Shao et al. 1996), etc. More interesting examples of composites, nanocomposites, starch, and cyclodextrin derivates for malachite green and other textile
dyes are collected in review papers (Crini 2006; Raval et al. 2017).
11.4.7 Ion-Exchange Resins
Ion-exchange resins (cation exchangers and anion exchangers) are popular materials for purification of industrial effluents. Ion exchangers reduce the bulk of toxic
load and convert it into a form in which it is less toxic. Very important feature of
ion-exchange reactions is separation and preconcentration of pollutants. Not only
anionic but also cationic resins can be applied for anionic (acid, direct, reactive) and
cationic type dyes (basic dyes), respectively. There are numerous literature reports
on the use of the polystyrene, polyacrylic, and phenol-formaldehyde ion-exchange
resins in the sorption of dyes from both aqueous solutions and wastewater
(Wawrzkiewicz 2010, 2011a, b, 2012a, b, 2013, 2014). Among the commercially
available anion exchangers and cation exchangers, the following resins Lewatit SP
112, Amberlite IRA 67, Amberlite FPA 51, Lewatit MP 62, Amberlyst A 23, Lewatit
MP 64, Lewatit MP 68, Amberlite IRA 478RF, Amberlite IRA 910, Amberlite IRA
A. Wołowicz and M. Wawrzkiewicz