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efficient sorbents for dyes wastewaters treatment; even the dye concentration is
small (at ppb or ppm levels). The main natural sources of chitin and chitosan are
fungi, insects, annelids, crustaceans, and mollusks, but chitin are usually isolated
from exoskeleton of crustaceans (crab, crayfish, krill) widely available by-product
of food processing, whereas chitosan is prepared during the N-deacetylation of chitin using a cheap chemical reagents. These materials are abundant, versatile, environmentally friendly, renewable, and biodegradable, and due to the way of their
production, they contribute to industrial solid wastes utilization. Moreover, they are
hydrophilic in character of high reactivity possessing cationic charge in acidic
pH. On the other hand, they possess some limitations such as variability in the polymer characteristics, nonporous structure, non-effectivity for cationic dyes (except
after derivatization), and strongly pH dependence. Additionally, they possess limited application in the column treatment due to hydrodynamic limitation and column fouling (Crini 2006; Crini and Badot 2011). Chitin contains
2-acetamido-2-deoxy-β-d-glucose through a β (1 → 4) linkage, whereas chitosan is
a nitrogenous (amino-based) polysaccharide containing chitosan 2-amino-2-deoxyβ- d-glucopyranose and 2-acetamido-2-deoxy-β-d-glucopyranose. Chemical stability of chitosan, high reactivity and selectivity, and excellent chelation behavior
make it competitive adsorbent to other biomaterials (Kyzas et al. 2017). Many studies proved that biosorbents of chitosan origin show high affinity for many classes
of dyes.
Chiou et al. (2004) and Chiou and Li (2002) applied cross-linked chitosan for
dyes: reactive blue 2, reactive red 2, reactive yellow 2, reactive yellow 86, reactive
red 189, acid orange 12, acid red 14, acid orange 7, and direct red 81. The adsorption capacities were in the range from 1911 to 2498 (g/kg) and were much higher
than those of commercial activated carbon (3.4–15.0 times) and chitin (2.7–27.4
times). Moreover the adsorption capacity of cross-linked chitosan is largely dependent of pH and biosorbent mass. Temperature and the cross-linking factor do not
play an important role.
The variability of chitosan was proved by Wu et al. (2000). Reactive red 222
removal efficiency using chitosan in form of flakes and bead obtained from fishery
wastes were paralleled. The uptake of reactive red 222 by chitosan (in form of
beads) was higher than that on flake-type (1037 mg/g for chitosan, bead-type, from
lobster; 1106 mg/g for chitosan, bead-type, from crab; 398 mg/g for chitosan, flaketype, from lobster; 293 mg/g for chitosan, flake-type, from crab). The reactive red
222 removal was faster for bead-type chitosan compared to flake-type chitosan.
Such acid dyes as green 25, orange 10, orange 12, red 18, and red 73 were
removed by chitosan obtained from crab shell. The adsorption capacities were in the
range from 645.1 mg/g to 973.3 mg/g (orange 12 (973.3 mg/g) > orange 10
(922.9 mg/g) > red 73 (728.2 mg/g) > red 18 (693.2 mg/g) > green 25 (645.1 mg/g))
(Wong et al. 2004).
Peat is a sedimentary rock consisting of organic matter in different stages of
decomposition. Moss, woody, herbaceous, and sedimentary peat can be distinguish.
It is abundant, cheap, and widely accessible sorbent, which has excellent adsorption
properties. The main ingredients of raw peat are lignin, cellulose, humic, and fulvic
A. Wołowicz and M. Wawrzkiewicz
efficient sorbents for dyes wastewaters treatment; even the dye concentration is
small (at ppb or ppm levels). The main natural sources of chitin and chitosan are
fungi, insects, annelids, crustaceans, and mollusks, but chitin are usually isolated
from exoskeleton of crustaceans (crab, crayfish, krill) widely available by-product
of food processing, whereas chitosan is prepared during the N-deacetylation of chitin using a cheap chemical reagents. These materials are abundant, versatile, environmentally friendly, renewable, and biodegradable, and due to the way of their
production, they contribute to industrial solid wastes utilization. Moreover, they are
hydrophilic in character of high reactivity possessing cationic charge in acidic
pH. On the other hand, they possess some limitations such as variability in the polymer characteristics, nonporous structure, non-effectivity for cationic dyes (except
after derivatization), and strongly pH dependence. Additionally, they possess limited application in the column treatment due to hydrodynamic limitation and column fouling (Crini 2006; Crini and Badot 2011). Chitin contains
2-acetamido-2-deoxy-β-d-glucose through a β (1 → 4) linkage, whereas chitosan is
a nitrogenous (amino-based) polysaccharide containing chitosan 2-amino-2-deoxyβ- d-glucopyranose and 2-acetamido-2-deoxy-β-d-glucopyranose. Chemical stability of chitosan, high reactivity and selectivity, and excellent chelation behavior
make it competitive adsorbent to other biomaterials (Kyzas et al. 2017). Many studies proved that biosorbents of chitosan origin show high affinity for many classes
of dyes.
Chiou et al. (2004) and Chiou and Li (2002) applied cross-linked chitosan for
dyes: reactive blue 2, reactive red 2, reactive yellow 2, reactive yellow 86, reactive
red 189, acid orange 12, acid red 14, acid orange 7, and direct red 81. The adsorption capacities were in the range from 1911 to 2498 (g/kg) and were much higher
than those of commercial activated carbon (3.4–15.0 times) and chitin (2.7–27.4
times). Moreover the adsorption capacity of cross-linked chitosan is largely dependent of pH and biosorbent mass. Temperature and the cross-linking factor do not
play an important role.
The variability of chitosan was proved by Wu et al. (2000). Reactive red 222
removal efficiency using chitosan in form of flakes and bead obtained from fishery
wastes were paralleled. The uptake of reactive red 222 by chitosan (in form of
beads) was higher than that on flake-type (1037 mg/g for chitosan, bead-type, from
lobster; 1106 mg/g for chitosan, bead-type, from crab; 398 mg/g for chitosan, flaketype, from lobster; 293 mg/g for chitosan, flake-type, from crab). The reactive red
222 removal was faster for bead-type chitosan compared to flake-type chitosan.
Such acid dyes as green 25, orange 10, orange 12, red 18, and red 73 were
removed by chitosan obtained from crab shell. The adsorption capacities were in the
range from 645.1 mg/g to 973.3 mg/g (orange 12 (973.3 mg/g) > orange 10
(922.9 mg/g) > red 73 (728.2 mg/g) > red 18 (693.2 mg/g) > green 25 (645.1 mg/g))
(Wong et al. 2004).
Peat is a sedimentary rock consisting of organic matter in different stages of
decomposition. Moss, woody, herbaceous, and sedimentary peat can be distinguish.
It is abundant, cheap, and widely accessible sorbent, which has excellent adsorption
properties. The main ingredients of raw peat are lignin, cellulose, humic, and fulvic
A. Wołowicz and M. Wawrzkiewicz