**1. Introduction**

The adsorption of heavy metals on the differently charged surfaces has been widely studied; on the one hand, mineral surfaces such as oxides, clays, soils, and activated carbons; and on the other hand, organic surfaces and biological surfaces.

Mineral surfaces: the most commonly used adsorbent is activated carbon, which has become a potential absorbent for wastewater [1–5]. Huang [1] studied the adsorption of Cd on activated carbon, which showed that the elimination efficiency increases when the pH increases; Ku [2] studied the coupling between two techniques adsorption on the CA and precipitation by hydroxides, which showed that the percentage of adsorption of Zn (II) increases with pH; and the same study was carried out on Cd, which found that the maximum adsorption of Cd is at pH = 9.5. Saito [6] used CA and sulphonated cottons for the removal of Cu and Cd from wastewater. The percentage of elimination reaches 98%. Most studies done on the CA have been undertaken for water treatment. However, most of the studies carried out on oxide surfaces have been undertaken to assimilate the behavior of heavy metals in the soil or the mechanism of transport and fixation

of metals by these types of surfaces. Swallow [7] studied the adsorption of Cu and Pb on the hydrous ferric oxide, he noted that this support shows a great affinity toward Pb and Cd. Anjana [8] showed that the adsorption of Zn on Fe (III) hydroxide increases with increasing pH. Spark [9] studied the adsorption of heavy metals on oxides and oxyhydroxides, which has shown that this adsorption is very dependent on pH. The study of Cd adsorption on Fe (OH)2, δ Al2O3, and Fe2O3 showed that the percentage of removal exceeds 80%. The hydroxide aluminosilicates were used for the adsorption of Zn (II) in alkaline medium [10]. Benjamin [11] studied the adsorption of Cd2+ on four oxide surfaces in the presence of certain complexing agents such as SO4 <sup>2</sup><sup>−</sup>, Cl<sup>−</sup>, and S2O3 <sup>2</sup><sup>−</sup>, and concluded that the interaction between metal ions and the complexing ligands in the presence of adsorbent surfaces can be divided into three categories based on the origin and the interaction force.


With regard to the clays, among the studies carried out, the adsorption of Cd on illite by Comans [12]. Schindler [13] showed that the importance of Cu, Cd, and Pb adsorption on kaolinite increases with increasing pH. Cadena [14] studied the adsorption of Pb on bentonite, which showed that the percentage of adsorption is 35%. There are also comparative adsorption studies between clay and sand, such as the study by El Khatib [15], which found that the amount of adsorbed Pb is very important in the case of clay as in the case of sand. Petersen [16] showed that the percentage of Cu adsorption on kaolinite exceeds 90%. Spark [17] found that the concentration of kaolinite has a small effect on the pH at which the adsorption process of Cd, Zn, Cu, and Co begins. Mrad [18] showed that the adsorption of Cd on montmorillonite is accompanied by a proton departure.

Biological surfaces: the most used adsorbents are active sludge and seaweed; indeed, many studies have been carried out for the removal of heavy metals by biological surfaces. Filip [19] studied the adsorption of Cu and Cd synthetic solutions and the elimination reached was 98% Cu and 100% Cd. Sloan [20] exploited different kinds of algae to eliminate Pb, Cd, Cu, and Zn at different concentrations. Nicolas [21] studied adsorption of heavy metals on active sludge. Roy [22] carried out the adsorption of the heavy metals, Cd, Co, Cr, Pb, Ni, and Zn, on two types of biomass, and found that the green alga Chlorella minutissima adsorbs more than 90% of the initial quantity of Pb, while Rice Hulls has an adsorption efficiency of more than 99%. However, Brown [23, 24] showed that the main constituents of active sludge surfaces are polysaccharides and proteins, while the dewaxed sludge mainly consists of lipopolysaccharides and proteins.

Organic surfaces: several studies on the fate of heavy metals in nature have shown that organic surfaces are primarily responsible for the transport, fixation, and distribution of heavy metals in nature. Thus, Lester [25, 26] found that adsorption of metal ions from wastewater is mainly due to organic matter consisting of polysaccharides, nucleic acids, and polypeptides. Among the most important adsorbents are cellulose and polysaccharides. Thus, Irwin [27] showed that wood cedar flours mixed with a base reduce the Cd concentration from 8.7 to 0.4 mg/l of

**239**

lobsters).

incineration.

other metals.

very effective for the elimination of Cu.

*Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan*

a synthetic solution with a 95.4% removal rate. Recently, Deans and Dixon [28] carried out a comparative study of the adsorption of heavy metals on several organic surfaces, cellulose, alginic acid, chitin, chitosan, carrageenan, carboxymethyl, hydroxamic acid, terephthalic acid, and its hydroxamic, which showed that the hydroxamic acid is the most effective adsorbent for the removal of metals under different conditions. Among the polysaccharides is chitin, which plays an important

The applications of chitin are diverse and numerous [30], which is used in the treatment of water, for its flocculating properties or for its retention properties of heavy metals. The importance of chitin as an unused resource has increased in recent years, due to its unique structure and numerous properties. Among them is the ability of this chelating polysaccharide, which seems to be the most promising property of chitin. Chitin is prepared in the form of a flocculant for the purification of municipal water [31, 32]. It was exploited in the Cu assay by adsorptionelution on a column [33]. It has also been exploited for the collection of heavy metals in seawater and these metals are then recovered by an appropriate washing of chitin [34]. Muzzarelli [35, 36] and Yang [37] also used chitin for the removal of heavy metals from wastewater and natural waters. Finally, Later Melchor [38, 39] studied the adsorption of Cu, Pb, and Cd on pure chitin extracted from crab shells as a function of pH, temperature, and salinity of the medium, which showed that this adsorption is very efficient and very fast and is not affected by the presence of

In parallel, it is found that chitin derivatives are used for selective removal of metal ions [35]. Thus chitosan, which is only deacetylated chitin, has been known especially as the most powerful adsorbent of natural origin [40]. Chitosan is very effective for the elimination of uranium [41]. Muzzarelli [42] also studied the elimination of Co and Cu from water using three chitin derivatives: serine glucan, aspartate glucan, and glycine glucan. Kurita [43] showed that chitin derivatives are

Studies on the raw chitin adsorption are few and concern in general the crude chitin extracted from the mushrooms. Huang [44, 45] tried to eliminate Cd by several species of chitin-rich fungi such as *Aspergillus oryzae*, *Aspergillus. clavatus*, and *Candida utilis*, showing an adsorption capacity according to the model of Langmuir, it has also studied the adsorption of Cu, Cd, Zn, and Ni on 12 species of fungi. Boukhlifi et al. [46, 47] studied the elimination of metals ions Zn, Pb, Cu, and Cd by raw chitin from different sources. The affinity of each metal for the adsorbent depends on the source used. A study on the competitive adsorption of metal ions on crude chitin showed that the retention of an ion is strongly influenced by the number and nature of the other ions present in the wastewater [48]. Boukhlifi et al. [49–51] applied the raw chitin shrimp for the treatment of real industrial discharges. Wales [52] also recovered Zn, Pb, Cu, and Cd by chitin/ chitosan micro fungi. Until now, the work on the raw chitin from shellfish, which represents 75% of fisheries waste are rare. From then, we were interested in this study to the valuation of gross chitin some crustaceans (shrimp, crabs, and

This chapter studied the behavior and adsorbent properties of raw chitin against Cd, Cu, Pb, and Zn metal ions. First of all, we will study the kinetic and isothermal study of the adsorption of metal ions on the raw chitin of different origins namely shrimp (Ccre), lobster (Clan), and crab (Ccra), then the study of series adsorption of metal ions, and finally, the study of sludge recovery generated from treatment by trying to study the regeneration of the adsorbent support by several cations or by

*DOI: http://dx.doi.org/10.5772/intechopen.88998*

role in the transport of heavy metals to sediments [29].

#### *Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan DOI: http://dx.doi.org/10.5772/intechopen.88998*

a synthetic solution with a 95.4% removal rate. Recently, Deans and Dixon [28] carried out a comparative study of the adsorption of heavy metals on several organic surfaces, cellulose, alginic acid, chitin, chitosan, carrageenan, carboxymethyl, hydroxamic acid, terephthalic acid, and its hydroxamic, which showed that the hydroxamic acid is the most effective adsorbent for the removal of metals under different conditions. Among the polysaccharides is chitin, which plays an important role in the transport of heavy metals to sediments [29].

The applications of chitin are diverse and numerous [30], which is used in the treatment of water, for its flocculating properties or for its retention properties of heavy metals. The importance of chitin as an unused resource has increased in recent years, due to its unique structure and numerous properties. Among them is the ability of this chelating polysaccharide, which seems to be the most promising property of chitin. Chitin is prepared in the form of a flocculant for the purification of municipal water [31, 32]. It was exploited in the Cu assay by adsorptionelution on a column [33]. It has also been exploited for the collection of heavy metals in seawater and these metals are then recovered by an appropriate washing of chitin [34]. Muzzarelli [35, 36] and Yang [37] also used chitin for the removal of heavy metals from wastewater and natural waters. Finally, Later Melchor [38, 39] studied the adsorption of Cu, Pb, and Cd on pure chitin extracted from crab shells as a function of pH, temperature, and salinity of the medium, which showed that this adsorption is very efficient and very fast and is not affected by the presence of other metals.

In parallel, it is found that chitin derivatives are used for selective removal of metal ions [35]. Thus chitosan, which is only deacetylated chitin, has been known especially as the most powerful adsorbent of natural origin [40]. Chitosan is very effective for the elimination of uranium [41]. Muzzarelli [42] also studied the elimination of Co and Cu from water using three chitin derivatives: serine glucan, aspartate glucan, and glycine glucan. Kurita [43] showed that chitin derivatives are very effective for the elimination of Cu.

Studies on the raw chitin adsorption are few and concern in general the crude chitin extracted from the mushrooms. Huang [44, 45] tried to eliminate Cd by several species of chitin-rich fungi such as *Aspergillus oryzae*, *Aspergillus. clavatus*, and *Candida utilis*, showing an adsorption capacity according to the model of Langmuir, it has also studied the adsorption of Cu, Cd, Zn, and Ni on 12 species of fungi. Boukhlifi et al. [46, 47] studied the elimination of metals ions Zn, Pb, Cu, and Cd by raw chitin from different sources. The affinity of each metal for the adsorbent depends on the source used. A study on the competitive adsorption of metal ions on crude chitin showed that the retention of an ion is strongly influenced by the number and nature of the other ions present in the wastewater [48]. Boukhlifi et al. [49–51] applied the raw chitin shrimp for the treatment of real industrial discharges. Wales [52] also recovered Zn, Pb, Cu, and Cd by chitin/ chitosan micro fungi. Until now, the work on the raw chitin from shellfish, which represents 75% of fisheries waste are rare. From then, we were interested in this study to the valuation of gross chitin some crustaceans (shrimp, crabs, and lobsters).

This chapter studied the behavior and adsorbent properties of raw chitin against Cd, Cu, Pb, and Zn metal ions. First of all, we will study the kinetic and isothermal study of the adsorption of metal ions on the raw chitin of different origins namely shrimp (Ccre), lobster (Clan), and crab (Ccra), then the study of series adsorption of metal ions, and finally, the study of sludge recovery generated from treatment by trying to study the regeneration of the adsorbent support by several cations or by incineration.

*Trace Metals in the Environment - New Approaches and Recent Advances*

ence of certain complexing agents such as SO4

and the interaction force.

metals.

properties of the surface.

of metals by these types of surfaces. Swallow [7] studied the adsorption of Cu and Pb on the hydrous ferric oxide, he noted that this support shows a great affinity toward Pb and Cd. Anjana [8] showed that the adsorption of Zn on Fe (III) hydroxide increases with increasing pH. Spark [9] studied the adsorption of heavy metals on oxides and oxyhydroxides, which has shown that this adsorption is very dependent on pH. The study of Cd adsorption on Fe (OH)2, δ Al2O3, and Fe2O3 showed that the percentage of removal exceeds 80%. The hydroxide aluminosilicates were used for the adsorption of Zn (II) in alkaline medium [10]. Benjamin [11] studied the adsorption of Cd2+ on four oxide surfaces in the pres-

that the interaction between metal ions and the complexing ligands in the presence of adsorbent surfaces can be divided into three categories based on the origin

• Metal-ligand complex can form in the solution and weakly adsorb.

on montmorillonite is accompanied by a proton departure.

mainly consists of lipopolysaccharides and proteins.

• Species can interact indirectly on the surface by altering the electrical

• Metal-ligand complex can be strongly adsorbed by improving the removal of

With regard to the clays, among the studies carried out, the adsorption of Cd on illite by Comans [12]. Schindler [13] showed that the importance of Cu, Cd, and Pb adsorption on kaolinite increases with increasing pH. Cadena [14] studied the adsorption of Pb on bentonite, which showed that the percentage of adsorption is 35%. There are also comparative adsorption studies between clay and sand, such as the study by El Khatib [15], which found that the amount of adsorbed Pb is very important in the case of clay as in the case of sand. Petersen [16] showed that the percentage of Cu adsorption on kaolinite exceeds 90%. Spark [17] found that the concentration of kaolinite has a small effect on the pH at which the adsorption process of Cd, Zn, Cu, and Co begins. Mrad [18] showed that the adsorption of Cd

Biological surfaces: the most used adsorbents are active sludge and seaweed; indeed, many studies have been carried out for the removal of heavy metals by biological surfaces. Filip [19] studied the adsorption of Cu and Cd synthetic solutions and the elimination reached was 98% Cu and 100% Cd. Sloan [20] exploited different kinds of algae to eliminate Pb, Cd, Cu, and Zn at different concentrations. Nicolas [21] studied adsorption of heavy metals on active sludge. Roy [22] carried out the adsorption of the heavy metals, Cd, Co, Cr, Pb, Ni, and Zn, on two types of biomass, and found that the green alga Chlorella minutissima adsorbs more than 90% of the initial quantity of Pb, while Rice Hulls has an adsorption efficiency of more than 99%. However, Brown [23, 24] showed that the main constituents of active sludge surfaces are polysaccharides and proteins, while the dewaxed sludge

Organic surfaces: several studies on the fate of heavy metals in nature have shown that organic surfaces are primarily responsible for the transport, fixation, and distribution of heavy metals in nature. Thus, Lester [25, 26] found that adsorption of metal ions from wastewater is mainly due to organic matter consisting of polysaccharides, nucleic acids, and polypeptides. Among the most important adsorbents are cellulose and polysaccharides. Thus, Irwin [27] showed that wood cedar flours mixed with a base reduce the Cd concentration from 8.7 to 0.4 mg/l of

<sup>2</sup><sup>−</sup>, Cl<sup>−</sup>, and S2O3

<sup>2</sup><sup>−</sup>, and concluded

**238**
