280
porous structure are likewise important features of adsorptive materials. With
increase of surface area and using more porous material, higher adsorption efficiency is obtained. Not only an economical aspect but also the process duration is
important. Dyes should be removed with high efficiency as well as in the shortest
possible time. Additionally, adsorptive materials should be able to remove various
types of pollutants, to be reused and function in a broad range of pH, temperature,
as well as dye concentrations.
Solid materials used in wastewaters treatment such as sorbents can occur in different chemical forms and geometrical structure of the surface. Moreover, they are
classified in various ways depending on the adopted criterion. Some of them are
presented below. Sorbents could be divided into a few classes:
1. Natural materials (wood, peat, chitin, and chitosan, clays, natural zeolites, coal)
2. Modified natural materials with a developed structure and improved properties
(activated carbon, silica gel, activated alumina)
3. Manufactured materials (zeolites, aluminosilicates, polymeric resins)
4. Agriculture wastes and by-products
5. Biosorbents (Crini et al. 2019)
The other authors (Dąbrowski 2001) classified sorbents into three categories
such as (1) carbon adsorbents (activated carbons, fullerenes, carbonaceous materials, activated carbon fibers, molecular carbon sieves), (2) mineral adsorbents (activated alumina, metal hydroxide and oxide, silica gels, zeolites, clay minerals,
pillared clays), and (3) other adsorbents (synthetic polymers, mixed adsorbents,
composite adsorbents). Crini et al. (2019) presented classification of sorbents into
two categories: (1) conventional adsorbents, activated carbons, inorganic materials,
and ion-exchange resin, and (2) nonconventional adsorbents, activated carbons prepared from the solid wastes as well as miscellaneous ones. Activated carbons, silica
gels, zeolites, and activated alumina are the most frequently commercially applied
sorbents from the conventional adsorbents group for sorption processes.
11.4 Removal of Dyes from Waters and Wastewaters Using
Various Adsorbents
11.4.1 Commercial Activated Carbon
The term active carbons includes a wide range of carbonaceous materials (amorphous) that are characterized by a high degree of porosity and surface reactivity as
well as the extended interparticle surface area. Active carbons are known to be very
efficacious adsorbents. However their production costs are very high. This group
includes commercial activated carbons and active carbons produced from agricultural waste materials (Crini et al. 2019).
The commercial activated carbons are one of the oldest materials most widely
utilized in industry as adsorbents, catalysts, support for catalysts, or reducing agents.
Due to great capacity of commercial activated carbons, they are the most effective
A. Wołowicz and M. Wawrzkiewicz
porous structure are likewise important features of adsorptive materials. With
increase of surface area and using more porous material, higher adsorption efficiency is obtained. Not only an economical aspect but also the process duration is
important. Dyes should be removed with high efficiency as well as in the shortest
possible time. Additionally, adsorptive materials should be able to remove various
types of pollutants, to be reused and function in a broad range of pH, temperature,
as well as dye concentrations.
Solid materials used in wastewaters treatment such as sorbents can occur in different chemical forms and geometrical structure of the surface. Moreover, they are
classified in various ways depending on the adopted criterion. Some of them are
presented below. Sorbents could be divided into a few classes:
1. Natural materials (wood, peat, chitin, and chitosan, clays, natural zeolites, coal)
2. Modified natural materials with a developed structure and improved properties
(activated carbon, silica gel, activated alumina)
3. Manufactured materials (zeolites, aluminosilicates, polymeric resins)
4. Agriculture wastes and by-products
5. Biosorbents (Crini et al. 2019)
The other authors (Dąbrowski 2001) classified sorbents into three categories
such as (1) carbon adsorbents (activated carbons, fullerenes, carbonaceous materials, activated carbon fibers, molecular carbon sieves), (2) mineral adsorbents (activated alumina, metal hydroxide and oxide, silica gels, zeolites, clay minerals,
pillared clays), and (3) other adsorbents (synthetic polymers, mixed adsorbents,
composite adsorbents). Crini et al. (2019) presented classification of sorbents into
two categories: (1) conventional adsorbents, activated carbons, inorganic materials,
and ion-exchange resin, and (2) nonconventional adsorbents, activated carbons prepared from the solid wastes as well as miscellaneous ones. Activated carbons, silica
gels, zeolites, and activated alumina are the most frequently commercially applied
sorbents from the conventional adsorbents group for sorption processes.
11.4 Removal of Dyes from Waters and Wastewaters Using
Various Adsorbents
11.4.1 Commercial Activated Carbon
The term active carbons includes a wide range of carbonaceous materials (amorphous) that are characterized by a high degree of porosity and surface reactivity as
well as the extended interparticle surface area. Active carbons are known to be very
efficacious adsorbents. However their production costs are very high. This group
includes commercial activated carbons and active carbons produced from agricultural waste materials (Crini et al. 2019).
The commercial activated carbons are one of the oldest materials most widely
utilized in industry as adsorbents, catalysts, support for catalysts, or reducing agents.
Due to great capacity of commercial activated carbons, they are the most effective
A. Wołowicz and M. Wawrzkiewicz