281
adsorbents in organic as well as mineral contaminants removal (Pyrzyńska 2008;
Ryczkowski 2012).
Active carbons are substances partly composed of graphite fine crystalline, from
elemental carbon in an amorphous form and various substances which are noncarbon, such as mineral substances and heteroatoms, e.g., hydrogen, oxygen, sulfur,
and nitrogen or phosphorus. Carbon as a major constituent of active carbons is present in the range 85–95%. The quantity and type of heteroatoms depend on the raw
materials used in the production process, production processes, as well as the procedure of their activation (heteroatoms introduced during the activation process).
Active, surface functional groups and the delocalized electrons result in acidic or
basic surface of active carbons (Shafeeyan et al. 2010; Wołowicz 2013). Good
adsorptive properties of carbonaceous materials are associated with their surface
chemical and porous structures (Bansal and Goyal 2005; Crini et al. 2019; Wołowicz
2013). They possess a large surface area which is usually in the range from 800 to
1500 m
2
/g (for the most widely applied active carbons) which is a result of existence
of internal porous structure (micropores, mesopores) and pore volume from 0.2 to
0.6 m
2
/g (in many cases pore volume is as large as 1 cm
3
/g) (Wołowicz 2013). The
examples of surface area of active carbons can be found in Katheresan et al. (2018).
The active carbons are often modified in order to improve their sorptive properties
using physical activation (two steps, (1) carbonization of the carbonaceous precursors (raw materials) by the pyrolysis process, (2) activation using the agents – air,
stream, carbon dioxide, mixture of oxidizing gases, high temperature 600–1200 °C)
or chemical activation (one or two steps conducted at the same time, (1) impregnation of the precursor (raw material) by chemicals, (2) heating in the flow of nitrogen
gases, low temperature 450–900 °C), e.g., introduction of nitrogen functional
groups into the surface of carbon (nitrogen functionalities) by the reaction
with reagents containing nitrogen (amines, ammonium, nitric acid) or activation
precursors containing nitrogen, oxidation by gases in order to introduce acidic
groups containing oxygen such as carboxylic, phenol, lactone, carbonyl, carboxylic
anhydride, quinone, pyrone, chromene etc. the acidic, basic and neutral ones etc.
(Foo and Hameed 2010; Shafeeyan et al. 2010; Yagub et al. 2014). Active carbons
(obtained by combustion, thermal decomposition, or partial combustion) are prepared usually in granular, powder, fibrous, and cloth forms (Bansal and Goyal
2005). The advantages and disadvantages of active carbons are presented in Fig. 11.6.
Active carbons can be successfully applied in dye removal from waters and
wastewaters (Crini et al. 2019) but such technology also possesses a few disadvantages. The commercial activated carbons are quite expensive materials and their
price increases with developing quality. They can be nonselective and ineffective
toward vat and disperse dyes, varied in quality; they create problems with their
removal after the use of spent active carbons. They are characterized by rapid saturation and difficulty with regeneration (high cost, loss of the adsorbent, not straightforward) (Crini et al. 2019; Yagub et al. 2014).
Dai (1998) applied commercial activated carbons (powder, 781-A type, the solution pH at zero-point charge = 6.2) for cationic dyes such as methyl green and
methyl violet as well as anionic dyes such as phenol red, carmine, and titan yellow
11 Characteristics and Adsorptive Treatment of Wastewaters Containing Dyes
adsorbents in organic as well as mineral contaminants removal (Pyrzyńska 2008;
Ryczkowski 2012).
Active carbons are substances partly composed of graphite fine crystalline, from
elemental carbon in an amorphous form and various substances which are noncarbon, such as mineral substances and heteroatoms, e.g., hydrogen, oxygen, sulfur,
and nitrogen or phosphorus. Carbon as a major constituent of active carbons is present in the range 85–95%. The quantity and type of heteroatoms depend on the raw
materials used in the production process, production processes, as well as the procedure of their activation (heteroatoms introduced during the activation process).
Active, surface functional groups and the delocalized electrons result in acidic or
basic surface of active carbons (Shafeeyan et al. 2010; Wołowicz 2013). Good
adsorptive properties of carbonaceous materials are associated with their surface
chemical and porous structures (Bansal and Goyal 2005; Crini et al. 2019; Wołowicz
2013). They possess a large surface area which is usually in the range from 800 to
1500 m
2
/g (for the most widely applied active carbons) which is a result of existence
of internal porous structure (micropores, mesopores) and pore volume from 0.2 to
0.6 m
2
/g (in many cases pore volume is as large as 1 cm
3
/g) (Wołowicz 2013). The
examples of surface area of active carbons can be found in Katheresan et al. (2018).
The active carbons are often modified in order to improve their sorptive properties
using physical activation (two steps, (1) carbonization of the carbonaceous precursors (raw materials) by the pyrolysis process, (2) activation using the agents – air,
stream, carbon dioxide, mixture of oxidizing gases, high temperature 600–1200 °C)
or chemical activation (one or two steps conducted at the same time, (1) impregnation of the precursor (raw material) by chemicals, (2) heating in the flow of nitrogen
gases, low temperature 450–900 °C), e.g., introduction of nitrogen functional
groups into the surface of carbon (nitrogen functionalities) by the reaction
with reagents containing nitrogen (amines, ammonium, nitric acid) or activation
precursors containing nitrogen, oxidation by gases in order to introduce acidic
groups containing oxygen such as carboxylic, phenol, lactone, carbonyl, carboxylic
anhydride, quinone, pyrone, chromene etc. the acidic, basic and neutral ones etc.
(Foo and Hameed 2010; Shafeeyan et al. 2010; Yagub et al. 2014). Active carbons
(obtained by combustion, thermal decomposition, or partial combustion) are prepared usually in granular, powder, fibrous, and cloth forms (Bansal and Goyal
2005). The advantages and disadvantages of active carbons are presented in Fig. 11.6.
Active carbons can be successfully applied in dye removal from waters and
wastewaters (Crini et al. 2019) but such technology also possesses a few disadvantages. The commercial activated carbons are quite expensive materials and their
price increases with developing quality. They can be nonselective and ineffective
toward vat and disperse dyes, varied in quality; they create problems with their
removal after the use of spent active carbons. They are characterized by rapid saturation and difficulty with regeneration (high cost, loss of the adsorbent, not straightforward) (Crini et al. 2019; Yagub et al. 2014).
Dai (1998) applied commercial activated carbons (powder, 781-A type, the solution pH at zero-point charge = 6.2) for cationic dyes such as methyl green and
methyl violet as well as anionic dyes such as phenol red, carmine, and titan yellow
11 Characteristics and Adsorptive Treatment of Wastewaters Containing Dyes