4.3 TG and DTG analysis

to cellulose and chitosan. The low crystallinity of chitosan is the result of the

FTIR studies were performed on cellulose, chitin and chitosan powders. Figure 4 shows the UATR-FTIR spectra of cellulose, chitin, and chitosan collected

of 3000–2800 cm<sup>1</sup> correspond to the -CH2 symmetrical and asymmetrical

The amide II band of chitin and chitosan is located at 1553 and 1586 cm<sup>1</sup>

FTIR spectra of cellulose, chitin, and chitosan in the wavenumber region of 4000–600 cm<sup>1</sup>

3234 cm<sup>1</sup> are attributed to the O-H stretching vibrations and the extensive interand intra-molecular hydrogen bonding network [55]. For chitin, the vibrations attributed to O-H and N-H stretching are visible at 3434 and 3256 cm<sup>1</sup> and for chitosan those peaks appear at 3434 and 3256 cm<sup>1</sup> [56, 57]. The bands in the region

stretching vibrations of polysaccharides [55–57]. Chitin exhibits the doublet amide I band at 1658 and 1619 cm<sup>1</sup> representing the presence of H-bonding in a C=O group with the NH group of the adjacent chain and the O-H group of the inter-chain [58].

tively [56, 57]. The peak at 1307 cm<sup>1</sup> corresponds to the amide III band (in-plane mode of CONH2 group) of chitin. Respective, amide I and C-N stretching of amide

1110 cm<sup>1</sup> are attributed to the anti-symmetrical bridge of C-O-C stretching and anti-symmetric in-plane stretching. The peaks at 1060 and 1025 cm<sup>1</sup> correspond to the C-O stretching of the polysaccharide [55–57]. The band at 895 cm<sup>1</sup> is

. The peaks of cellulose at 3335 and

. The vibrations at 1152 and

.

, respec-

deacetylation process.

Figure 4.

10

4.2 FTIR characterization

Advanced Sorption Process Applications

in the wavenumber range of 4000–600 cm<sup>1</sup>

III of chitosan appear at around 1647 and 1318 cm<sup>1</sup>

assigned to β-linkage of the polysaccharide [55–57].

High-resolution thermogravimetry (TG) profiles recorded in flowing nitrogen (N2) were used to investigate the thermal stability of cellulose, chitin and chitosan, see Figure 5(a). All samples display two main weight loss regions at 35–150 and 250–450°C. In the first region, approximately, 5.1–9.0% of the weight loss was observed, which is attributed to the removal of physically adsorbed water. The second region represents the largest weight loss of 90.4, 86.6 and 63.4% for cellulose (1), chitin (2) and chitosan (3), respectively, corresponding to the degradation of polysaccharide structure of the biopolymer. The differential thermogravimetric (DTG) profiles generated from TG data are shown in Figure 5(b). The DTG curves for cellulose, chitin, and chitosan exhibit the main decomposition peaks at 371, 391 and 300°C, respectively. These results suggest that among three biopolymers, chitin has the highest thermal stability while chitosan has the least thermal stability.

## 4.4 SEM studies

The morphological characteristic of cellulose, chitin and chitosan was investigated and Figure 6 shows the comparison of typical surface morphologies for cellulose, chitin and chitosan. As it can be seen, all samples exhibited more irregular, flat, rough nanofiber surface with no porosity.

Figure 5. (a) TG and (b) DTG profiles of cellulose, chitin and chitosan.

Figure 6.

SEM images of (a) microcrystalline cellulose, (b) chitin and (c) chitosan at 100 um magnification.

## 5. Applications of biopolymer-based materials in sorption

With the rapid industrialization, more environmental concerns (such as industrial discharge of organic dyes and heavy metal ions, oil and solvent spillage, and emission of greenhouse gases including carbon dioxide (CO2)) have emerged as a critical worldwide issue, imposing detrimental damages to the environment, economy and human health. Recently, biopolymer-based materials being sustainable, readily available, biodegradable, economical, and environmentally-friendly, they are widely investigated both in industry and research as a green approach in remediating those issues. In this section, we discuss the use of cellulose-, chitin-, and chitosan-based materials as sorbents for four different applications including removal of organic dyes and heavy metals, oil and solvent spillage cleanup and CO2 adsorption.

prepared ultralight aerogels from cellulose nanofibrils (CNFs) derived from rice straw [81]. These ultra-lightweight aerogels have been studied as adsorbents for the removal of cationic dye malachite green (MG) dye from aqueous media. The highest adsorption capacity of MG was found to be 212.7 mg/g. They also reported a 100% MG removal via four consecutive adsorptions at a 1:5 mg/mL aerogel/MG ratio and 10 mg/L dye concentration and 92% MG adsorption in a single batch at 10:5 mg/mL aerogel/MG ratio and 100 mg/L dye concentration. The adsorption process obeyed a pseudo-second-order kinetic model and monolayer Langmuir adsorption isotherm. The dye desorption was also achieved by increasing ionic strength, leading to the recovery of both dye and CNF aerogel. Ruan and coworkers prepared porous 2,3-dialdehyde cellulose-chitosan (DAC-CS) beads and their applications in the removal of Congo red dye [82]. DAC-CS beads showed 100% dye removal at a capacity of 200 mg/g at pH. 2 in 100 g/L dye solution. About 93% of the adsorbed Congo red in DAC-CS beads could be desorbed at pH. 12 NaOH solution. A similar trend was observed in the second cycle with the adsorption and desorption of 100 and 89%, respectively. Cross-linked quaternized cellulose nanofibrils (Q-CNFs) have been investigated as adsorbents for removal of three different anionic dyes by Maatar and Boufi [83]. They reported the adsorption capacity of approximately 160, 230, and 560 mg/g for red 180, blue CR19, and orange 142 dye, respectively. The authors also confirmed the main contribution of electrostatic interactions between positive sites and the CNF surface and dye sulfonate groups by zeta potential measurements. The regeneration of the Q-CNF sorbent could be achieved by extraction with KCl solution in ethanol-water

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization…

DOI: http://dx.doi.org/10.5772/intechopen.80898

Kinetics of the adsorption of reactive yellow 2 (RY2) and reactive black 5 (RB5) by chitin was investigated by Akkaya et al. [84]. They concluded that the adsorption of RY2 by chitin from aqueous solution is favorable at low temperature and pH and the adsorption of RB5 by chitin is favorable at high temperature and pH. Cao and coworkers studied the adsorption isotherms and kinetic analysis of methylene blue (MB) onto porous chitin sorbents (PChs) with different content of chitin, ranging from 0.9 to 3.5% [85]. The maximum adsorption capacity of 384 mg/g with 79.8% MB removal was observed for PChs containing 3.5% chitin. The same adsorption capacity with 65% removal ratio was observed after six repetitive cycles. The adsorption equilibrium followed Freundlich isotherm model. Xu and coworkers reported the synthesis and efficient removal of MB by nanocomposite microspheres fabricated from chitin and clay [86]. These chitin/clay microspheres (CCMs) showed a maximum adsorption capability of 156.7 mg/g. A dye removal of 99.99% was observed within 20 at a low MB concentration of 10 mg/g. They also demonstrated a stability over five adsorption/desorption cycles for CCMs. Their kinetic data fitted well with the pseudo-second-order and monolayer Langmuir isotherm models. Gopi et al. prepared a chitin nanowhisker (ChNW)-functionalized polyvinylidene fluoride (PVDF) membrane using electrospinning technique [87]. They reported a maximum adsorption capacity of 72.6 mg/g and 88.9% removal efficiency of indigo carmine (IC) dye with their PVDF/ChNW (15%:1% wt.) com-

Xu and coworkers synthesized poly(2-acrylamido-2-methylpropane sulfonic acid grafted magnetic chitosan microspheres (PMCMs) for MB adsorption [88]. They investigated the effects of initial solution pH (1.0–10.0), temperature (30–50°C), contact time (0–660 min) and initial concentration (50–1600 mg/L) on dye adsorption kinetics. At pH. 9, PMCMs exhibited maximum MB sorption capacity of 1000, 1250 and 1428 mg/g at 30, 40 and 50°C, respectively. They also showed that the adsorption capacity increased with increasing of the initial solution pH and temperature. The adsorption kinetic and adsorption equilibrium

mixture.

13

posite membrane as compared to neat PVDF.

#### 5.1 Dye removal

Industries including textile, leather, paper, printing, and paint utilize large amounts of water for processing have the potential to contaminate waterways through the discharge of organic dyes into natural water resources and water treatment systems. Over 10,000 different textile dyes with an estimated annual production of over 7 <sup>10</sup><sup>5</sup> tons are available commercially [59, 60]. Most of these organic dyes are excessively used and 10–20% is directly discharged as aqueous effluents into different water bodies [61]. Most problematic ones are the brightly colored, water-soluble reactive and acid dyes as these dyes cannot be removed through conventional treatment systems. Discharging of organic dyes into water bodies has raised acute and chronic concerns to the ecosystems and human health. For example, the release of those organic dyes can lead to eutrophication, nonesthetic pollution and imbalance in the aquatic biological systems and also causes chronic toxicity, carcinogenicity and neurotoxicity towards humans and animals. Commonly applied technologies for removing organic dyes from wastewater include chemical precipitation and adsorption [62, 63], electrochemical oxidation and reduction [64], aerobic and anaerobic treatment [65, 66], coagulation and flocculation [67, 68], membrane separation [69], ultra-filtration [70], H2O2/ultraviolet (UV) and photocatalysis [71–73], ion exchange [74], sonochemical degradation [71], Fenton and heterogeneous Fenton-like catalysis [75–77], electrolysis [78], and advanced oxidation processes (AOPs) [56, 79]. At present, there is a critical need for research that enables new means of inexpensive, reusable, environmentally and energetically sustainable wastewater management systems for wastewater treatment. Recently, biopolymer-based materials have attracted interests as emerging alternative techniques for the removal of organic dyes from industrial effluents due to their relative abundance, eco-friendly, high thermal and mechanical stability, low cost, nontoxicity, easy functionalization, and excellent sorption capacities. Here, we report the roles of biopolymer-based materials mainly derived from cellulose, chitin, and chitosan as sorption materials for the removal of organic dyes from industrial wastewater.

Liu et al. investigated the porous cellulose-based bioadsorbent for the removal of anionic dye acid blue 93 (AB93) and cationic dye methylene blue (MB) from single and binary dye solutions by grafting acrylic acid and acrylamide onto cellulose surface [80]. They reported maximum sorption capacity of 1372 mg/g at an initial absorbent concentration of 2500 mg/L for both of AB93 and MB with a reusability up to three consecutive cycles. The adsorption process followed the pseudo-secondorder kinetic model and the Freundlich isotherm model. Jiang and coworkers

#### Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization… DOI: http://dx.doi.org/10.5772/intechopen.80898

prepared ultralight aerogels from cellulose nanofibrils (CNFs) derived from rice straw [81]. These ultra-lightweight aerogels have been studied as adsorbents for the removal of cationic dye malachite green (MG) dye from aqueous media. The highest adsorption capacity of MG was found to be 212.7 mg/g. They also reported a 100% MG removal via four consecutive adsorptions at a 1:5 mg/mL aerogel/MG ratio and 10 mg/L dye concentration and 92% MG adsorption in a single batch at 10:5 mg/mL aerogel/MG ratio and 100 mg/L dye concentration. The adsorption process obeyed a pseudo-second-order kinetic model and monolayer Langmuir adsorption isotherm. The dye desorption was also achieved by increasing ionic strength, leading to the recovery of both dye and CNF aerogel. Ruan and coworkers prepared porous 2,3-dialdehyde cellulose-chitosan (DAC-CS) beads and their applications in the removal of Congo red dye [82]. DAC-CS beads showed 100% dye removal at a capacity of 200 mg/g at pH. 2 in 100 g/L dye solution. About 93% of the adsorbed Congo red in DAC-CS beads could be desorbed at pH. 12 NaOH solution. A similar trend was observed in the second cycle with the adsorption and desorption of 100 and 89%, respectively. Cross-linked quaternized cellulose nanofibrils (Q-CNFs) have been investigated as adsorbents for removal of three different anionic dyes by Maatar and Boufi [83]. They reported the adsorption capacity of approximately 160, 230, and 560 mg/g for red 180, blue CR19, and orange 142 dye, respectively. The authors also confirmed the main contribution of electrostatic interactions between positive sites and the CNF surface and dye sulfonate groups by zeta potential measurements. The regeneration of the Q-CNF sorbent could be achieved by extraction with KCl solution in ethanol-water mixture.

Kinetics of the adsorption of reactive yellow 2 (RY2) and reactive black 5 (RB5) by chitin was investigated by Akkaya et al. [84]. They concluded that the adsorption of RY2 by chitin from aqueous solution is favorable at low temperature and pH and the adsorption of RB5 by chitin is favorable at high temperature and pH. Cao and coworkers studied the adsorption isotherms and kinetic analysis of methylene blue (MB) onto porous chitin sorbents (PChs) with different content of chitin, ranging from 0.9 to 3.5% [85]. The maximum adsorption capacity of 384 mg/g with 79.8% MB removal was observed for PChs containing 3.5% chitin. The same adsorption capacity with 65% removal ratio was observed after six repetitive cycles. The adsorption equilibrium followed Freundlich isotherm model. Xu and coworkers reported the synthesis and efficient removal of MB by nanocomposite microspheres fabricated from chitin and clay [86]. These chitin/clay microspheres (CCMs) showed a maximum adsorption capability of 156.7 mg/g. A dye removal of 99.99% was observed within 20 at a low MB concentration of 10 mg/g. They also demonstrated a stability over five adsorption/desorption cycles for CCMs. Their kinetic data fitted well with the pseudo-second-order and monolayer Langmuir isotherm models. Gopi et al. prepared a chitin nanowhisker (ChNW)-functionalized polyvinylidene fluoride (PVDF) membrane using electrospinning technique [87]. They reported a maximum adsorption capacity of 72.6 mg/g and 88.9% removal efficiency of indigo carmine (IC) dye with their PVDF/ChNW (15%:1% wt.) composite membrane as compared to neat PVDF.

Xu and coworkers synthesized poly(2-acrylamido-2-methylpropane sulfonic acid grafted magnetic chitosan microspheres (PMCMs) for MB adsorption [88]. They investigated the effects of initial solution pH (1.0–10.0), temperature (30–50°C), contact time (0–660 min) and initial concentration (50–1600 mg/L) on dye adsorption kinetics. At pH. 9, PMCMs exhibited maximum MB sorption capacity of 1000, 1250 and 1428 mg/g at 30, 40 and 50°C, respectively. They also showed that the adsorption capacity increased with increasing of the initial solution pH and temperature. The adsorption kinetic and adsorption equilibrium

5. Applications of biopolymer-based materials in sorption

Advanced Sorption Process Applications

adsorption.

5.1 Dye removal

from industrial wastewater.

12

With the rapid industrialization, more environmental concerns (such as industrial discharge of organic dyes and heavy metal ions, oil and solvent spillage, and emission of greenhouse gases including carbon dioxide (CO2)) have emerged as a critical worldwide issue, imposing detrimental damages to the environment, economy and human health. Recently, biopolymer-based materials being sustainable, readily available, biodegradable, economical, and environmentally-friendly, they are widely investigated both in industry and research as a green approach in remediating those issues. In this section, we discuss the use of cellulose-, chitin-, and chitosan-based materials as sorbents for four different applications including removal of organic dyes and heavy metals, oil and solvent spillage cleanup and CO2

Industries including textile, leather, paper, printing, and paint utilize large amounts of water for processing have the potential to contaminate waterways through the discharge of organic dyes into natural water resources and water treatment systems. Over 10,000 different textile dyes with an estimated annual production of over 7 <sup>10</sup><sup>5</sup> tons are available commercially [59, 60]. Most of these organic dyes are excessively used and 10–20% is directly discharged as aqueous effluents into different water bodies [61]. Most problematic ones are the brightly colored, water-soluble reactive and acid dyes as these dyes cannot be removed through conventional treatment systems. Discharging of organic dyes into water bodies has raised acute and chronic concerns to the ecosystems and human health. For example, the release of those organic dyes can lead to eutrophication, nonesthetic pollution and imbalance in the aquatic biological systems and also causes chronic toxicity, carcinogenicity and neurotoxicity towards humans and animals. Commonly applied technologies for removing organic dyes from wastewater include chemical precipitation and adsorption [62, 63], electrochemical oxidation and reduction [64], aerobic and anaerobic treatment [65, 66], coagulation and flocculation [67, 68], membrane separation [69], ultra-filtration [70], H2O2/ultraviolet (UV) and photocatalysis [71–73], ion exchange [74], sonochemical degradation [71], Fenton and heterogeneous Fenton-like catalysis [75–77], electrolysis [78], and advanced oxidation processes (AOPs) [56, 79]. At present, there is a critical need for research that enables new means of inexpensive, reusable, environmentally and energetically sustainable wastewater management systems for wastewater treatment. Recently, biopolymer-based materials have attracted interests as emerging alternative techniques for the removal of organic dyes from industrial effluents due to their relative abundance, eco-friendly, high thermal and mechanical stability, low cost, nontoxicity, easy functionalization, and excellent sorption capacities. Here, we report the roles of biopolymer-based materials mainly derived from cellulose, chitin, and chitosan as sorption materials for the removal of organic dyes

Liu et al. investigated the porous cellulose-based bioadsorbent for the removal of anionic dye acid blue 93 (AB93) and cationic dye methylene blue (MB) from single and binary dye solutions by grafting acrylic acid and acrylamide onto cellulose surface [80]. They reported maximum sorption capacity of 1372 mg/g at an initial absorbent concentration of 2500 mg/L for both of AB93 and MB with a reusability up to three consecutive cycles. The adsorption process followed the pseudo-secondorder kinetic model and the Freundlich isotherm model. Jiang and coworkers

data followed the pseudo-second-order kinetic model and monolayer Langmuir isotherm model, respectively. PMCMs could also be separated under external magnetic field and regenerated under acidic conditions. Naseeruteen et al. exhibited the removal of Malachite Green (MG) by mesoporous chitosan ionic liquid beads prepared from chitosan and 1-butyl-3-methylimidazolium based ionic liquids [89]. The effects of initial pH, adsorbent dosage, agitation time and initial MG concentration have also been investigated. The optimum conditions reported were pH 4.0, 0.008 g of adsorbent dosage and 20 min of agitation time. The data obtained at pH 4 fitted well to a pseudo-second order kinetic model and followed the Langmuir model. The maximum adsorption capacity obtained for two chitosan beads prepared from 1-butyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium was 8.07 and 0.24 mg/g respectively.

98.3% desorption efficiency in 0.1 M H2SO4 solution. This adsorption equilibrium followed the pseudo-second order model and the Langmuir monolayer model. Duan and coworkers presented the fabrication of lignin/chitin films from a binary solvent system composed of the ionic liquid 1-butyl-3-methylimidazolium acetate and γ-valerolactone and their application as an adsorbent for Fe(III) and Cu (II) cation uptake from aqueous solutions [98]. Lignin/chitin film showed the adsorption capacity of 84 and 22 wt% for Fe(III) and Cu(II) cations within 48 h. During the regeneration process up to 12 and 46 wt%, respectively, could be desorbed. The adsorption isotherms for both Fe(III) and Cu(II) obeyed the Langmuir model. Ethylenediaminetetraacetic acid (EDTA) modified β-cyclodextrin/ chitosan (CDCS-EDTA) composite was prepared and applied for the removal of Pb

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization…

(II) and anionic dye acid red 73 (AR) by Wu and coworkers [99]. They also

8 mg/g) and (6.1 and 13 mg/g), respectively.

DOI: http://dx.doi.org/10.5772/intechopen.80898

5.3 Oil and solvent spillage cleanup

discussed below.

15

investigated the effects of adsorbent dose, contact time and pH value on the CDCS-EDTA adsorption efficiency. The maximum adsorption capacities reported were 114.8 and 754.6 mg g<sup>1</sup> for Pb(II) and AR under optimal conditions with adsorption efficiently of 93.4 and 92.1%, respectively. Both adsorption processes followed the pseudo-second-order adsorption kinetic model and the Langmuir isotherm model. Kwok et al. studied the sorption of anionic species arsenite, As(III) ions and arsenate, AS (V) ions onto chitosan and nanochitosan [100]. The equilibrium adsorption capacity of chitosan and nanochitosan for As(III) and As(V) ions were (0.5 and

An oil or a solvent spill is the accidental or intentional discharge of petroleum hydrocarbons into the environment, especially the aquatic ecosystem. Oil and solvent spills have become a serious environmental problem due to the increasing use, exploration, production and transportation of oils and solvents worldwide by various petrochemical and chemical industries. Those spillages lead to the pollution of aquatic ecosystems and natural water resources including underground water streams and coastal waters and affect both human and animal health through inhalation, skin, digestion, and eye irritation. Therefore, efficient and rapid removal of oil and solvent spills on the surface of water is imperative for protecting the aquatic environment, water resources, and subsequently human and animal health. Currently available oil and solvent spill techniques include physical diffusion, insitu burning, bioremediation, and mechanical recovery [101, 102]. Among those technologies, cleaning the spilled oil and solvents by physical adsorbents is an attractive approach because of their ease of use and simplicity. Biopolymer-based adsorbents have been widely investigated for cleanup of oil and solvents due to their relative abundance, sustainability, low-cost, selectivity, fast adsorption kinetics, reusability and environmental benignity. Some recent developments in the use of biopolymer-based materials in oil and solvent spillage cleanup processes are

Ao et al. reported the synthesis and separation of different oil/water mixtures using a cellulose hydrogel-coated mesh (CHM) [103]. They reported selective separation of a series of mixtures including hexane, cyclohexane, petroleum ether, liquid paraffin, pump oil and xylene with a high separation efficiency of over 98.9% and a high flux of 12,885 L/ m2 h. Their material also showed high reusability, antisalt properties, and stability after 60 successive cycles of separation with a separation efficiency of >98.2%. Magnetic hydrophobic polyvinyl alcohol (PVA)-cellulose nanofiber (CNF) aerogels (MHPCA) were prepared and used as effective oil absorbents by Xu and coworkers [104]. A series of oils including soybean oil, corn germ oil, pump oil, used pump oil, gasoline, motor oil, ethanol, and dimethylformamide

#### 5.2 Removal of heavy metals

The surge in energy production and the increasing use of heavy metals in various industrial processes have led to the generation of large quantities of industrial waste containing heavy metals. Therefore, heavy metals are released into the environment including air, water, soil, and biosphere in excessive amounts on daily basis. Heavy metal ions are mainly elements from the fourth period of the periodic table including chromium (Cr), arsenic (As), cobalt (Co), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), and mercury (Hg) and have a high atomic weight and a density at least 5 times higher than that of water [90]. Heavy metals are typically toxic, persistent, non-biodegradable and bioaccumulative. Due to the high solubility, heavy metals are easily absorbed by plants and aquatic species and subsequently enter the food chains and then the human body. The presence of high levels of heavy metals in the human body may cause various health effects including skin irritations, stomach cramps, vomiting, multiple organ damage, birth defects, nerve system damage and development of autoimmunity. Most commonly used techniques for the removal of heavy metals include membrane filtration, adsorption, coagulation, chemical precipitation, ion-exchange, electrochemical, biological treatments and advanced oxidation processes [91]. However, adsorption technologies are widely considered as cheap and energy efficient solutions for removal of heavy metals. Biopolymers including cellulose, chitin, and chitosan have been widely investigated as sorbents for remediation of heavy metals due to their excellent sorption properties and environmental benignity [92–94]. Here we present, recently reported applications of biopolymer-based materials for the removal of heavy metals.

d'Halluin et al. prepared a chemically modified cellulose filter paper with ethylenediaminetetraacetic acid (EDTA) for heavy metal remediation in water [95]. Cellulose-EDTA composite showed 90–95% removal efficiency for various heavy metal ions including Ag(I), Pb(II), Cd(II), Ni(II), Zn(II), Sn(II), and Cu(II). They also investigated the adsorption kinetics using Langmuir, Freundlich, and Temkin isotherms and the recyclability of their material. Fakhre and coworkers synthesized a supramolecular polysaccharide composite material from cellulose (CEL) and dibenzo-18-crown 6 (DB18C6) using ceric ammonium nitrate as initiator [96]. They studied the removal of five different heavy metal ions including Cd2+, Zn2+, Ni2+, Pb2+ and Cu2+ by [CEL + DB18C6] composites. They reported adsorption capacities and percentage of metals removal of (197 mg/g, 98%), (180 mg/g, 94%), (186 mg/ g, 93%), (194 mg/g, 97%), and (192 mg/g, 96%) for Cd2+, Zn2+, Ni2+, Pb2+ and Cu2+, respectively. The regeneration of the material is dependent on the type and concentration of regenerating solution (NH4Cl, HNO3, NaCl and CaCl2). Shao et al. studied the removal of Cu2+ ions by a porous waste paper (WP)-chitosan adsorbent (CSA) [97]. WP-CSA exhibited adsorption capacity of 156.3 mg/g for Cu2+ and

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization… DOI: http://dx.doi.org/10.5772/intechopen.80898

98.3% desorption efficiency in 0.1 M H2SO4 solution. This adsorption equilibrium followed the pseudo-second order model and the Langmuir monolayer model.

Duan and coworkers presented the fabrication of lignin/chitin films from a binary solvent system composed of the ionic liquid 1-butyl-3-methylimidazolium acetate and γ-valerolactone and their application as an adsorbent for Fe(III) and Cu (II) cation uptake from aqueous solutions [98]. Lignin/chitin film showed the adsorption capacity of 84 and 22 wt% for Fe(III) and Cu(II) cations within 48 h. During the regeneration process up to 12 and 46 wt%, respectively, could be desorbed. The adsorption isotherms for both Fe(III) and Cu(II) obeyed the Langmuir model. Ethylenediaminetetraacetic acid (EDTA) modified β-cyclodextrin/ chitosan (CDCS-EDTA) composite was prepared and applied for the removal of Pb (II) and anionic dye acid red 73 (AR) by Wu and coworkers [99]. They also investigated the effects of adsorbent dose, contact time and pH value on the CDCS-EDTA adsorption efficiency. The maximum adsorption capacities reported were 114.8 and 754.6 mg g<sup>1</sup> for Pb(II) and AR under optimal conditions with adsorption efficiently of 93.4 and 92.1%, respectively. Both adsorption processes followed the pseudo-second-order adsorption kinetic model and the Langmuir isotherm model. Kwok et al. studied the sorption of anionic species arsenite, As(III) ions and arsenate, AS (V) ions onto chitosan and nanochitosan [100]. The equilibrium adsorption capacity of chitosan and nanochitosan for As(III) and As(V) ions were (0.5 and 8 mg/g) and (6.1 and 13 mg/g), respectively.

#### 5.3 Oil and solvent spillage cleanup

data followed the pseudo-second-order kinetic model and monolayer Langmuir isotherm model, respectively. PMCMs could also be separated under external magnetic field and regenerated under acidic conditions. Naseeruteen et al. exhibited the removal of Malachite Green (MG) by mesoporous chitosan ionic liquid beads prepared from chitosan and 1-butyl-3-methylimidazolium based ionic liquids [89]. The effects of initial pH, adsorbent dosage, agitation time and initial MG concentration have also been investigated. The optimum conditions reported were pH 4.0, 0.008 g of adsorbent dosage and 20 min of agitation time. The data obtained at pH 4 fitted well to a pseudo-second order kinetic model and followed the Langmuir model. The maximum adsorption capacity obtained for two chitosan beads prepared from 1-butyl-3-methylimidazolium acetate and

The surge in energy production and the increasing use of heavy metals in various industrial processes have led to the generation of large quantities of industrial waste containing heavy metals. Therefore, heavy metals are released into the environment including air, water, soil, and biosphere in excessive amounts on daily basis. Heavy metal ions are mainly elements from the fourth period of the periodic table including chromium (Cr), arsenic (As), cobalt (Co), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), and mercury (Hg) and have a high atomic weight and a density at least 5 times higher than that of water [90]. Heavy metals are typically toxic, persistent, non-biodegradable and bioaccumulative. Due to the high solubility, heavy metals are easily absorbed by plants and aquatic species and subsequently enter the food chains and then the human body. The presence of high levels of heavy metals in the human body may cause various health effects including skin irritations, stomach cramps, vomiting, multiple organ damage, birth defects, nerve system damage and development of autoimmunity. Most commonly used techniques for the removal of heavy metals include membrane filtration, adsorption, coagulation, chemical precipitation, ion-exchange, electrochemical, biological treatments and advanced oxidation processes [91]. However, adsorption technologies are widely considered as cheap and energy efficient solutions for removal of heavy metals. Biopolymers including cellulose, chitin, and chitosan have been widely investigated as sorbents for remediation of heavy metals due to their excellent sorption properties and environmental benignity [92–94]. Here we present, recently reported applications

1-butyl-3-methylimidazolium was 8.07 and 0.24 mg/g respectively.

of biopolymer-based materials for the removal of heavy metals.

d'Halluin et al. prepared a chemically modified cellulose filter paper with ethylenediaminetetraacetic acid (EDTA) for heavy metal remediation in water [95]. Cellulose-EDTA composite showed 90–95% removal efficiency for various heavy metal ions including Ag(I), Pb(II), Cd(II), Ni(II), Zn(II), Sn(II), and Cu(II). They also investigated the adsorption kinetics using Langmuir, Freundlich, and Temkin isotherms and the recyclability of their material. Fakhre and coworkers synthesized a supramolecular polysaccharide composite material from cellulose (CEL) and dibenzo-18-crown 6 (DB18C6) using ceric ammonium nitrate as initiator [96]. They studied the removal of five different heavy metal ions including Cd2+, Zn2+, Ni2+, Pb2+ and Cu2+ by [CEL + DB18C6] composites. They reported adsorption capacities and percentage of metals removal of (197 mg/g, 98%), (180 mg/g, 94%), (186 mg/ g, 93%), (194 mg/g, 97%), and (192 mg/g, 96%) for Cd2+, Zn2+, Ni2+, Pb2+ and Cu2+, respectively. The regeneration of the material is dependent on the type and concentration of regenerating solution (NH4Cl, HNO3, NaCl and CaCl2). Shao et al. studied the removal of Cu2+ ions by a porous waste paper (WP)-chitosan adsorbent (CSA) [97]. WP-CSA exhibited adsorption capacity of 156.3 mg/g for Cu2+ and

5.2 Removal of heavy metals

Advanced Sorption Process Applications

14

An oil or a solvent spill is the accidental or intentional discharge of petroleum hydrocarbons into the environment, especially the aquatic ecosystem. Oil and solvent spills have become a serious environmental problem due to the increasing use, exploration, production and transportation of oils and solvents worldwide by various petrochemical and chemical industries. Those spillages lead to the pollution of aquatic ecosystems and natural water resources including underground water streams and coastal waters and affect both human and animal health through inhalation, skin, digestion, and eye irritation. Therefore, efficient and rapid removal of oil and solvent spills on the surface of water is imperative for protecting the aquatic environment, water resources, and subsequently human and animal health. Currently available oil and solvent spill techniques include physical diffusion, insitu burning, bioremediation, and mechanical recovery [101, 102]. Among those technologies, cleaning the spilled oil and solvents by physical adsorbents is an attractive approach because of their ease of use and simplicity. Biopolymer-based adsorbents have been widely investigated for cleanup of oil and solvents due to their relative abundance, sustainability, low-cost, selectivity, fast adsorption kinetics, reusability and environmental benignity. Some recent developments in the use of biopolymer-based materials in oil and solvent spillage cleanup processes are discussed below.

Ao et al. reported the synthesis and separation of different oil/water mixtures using a cellulose hydrogel-coated mesh (CHM) [103]. They reported selective separation of a series of mixtures including hexane, cyclohexane, petroleum ether, liquid paraffin, pump oil and xylene with a high separation efficiency of over 98.9% and a high flux of 12,885 L/ m2 h. Their material also showed high reusability, antisalt properties, and stability after 60 successive cycles of separation with a separation efficiency of >98.2%. Magnetic hydrophobic polyvinyl alcohol (PVA)-cellulose nanofiber (CNF) aerogels (MHPCA) were prepared and used as effective oil absorbents by Xu and coworkers [104]. A series of oils including soybean oil, corn germ oil, pump oil, used pump oil, gasoline, motor oil, ethanol, and dimethylformamide

(DMF), were tested and MHPCA showed oil absorption capacity in the range of 59–136 g/g. MHPCA exhibited magnetically driven oil absorption and elasticity after 30 compression-release cycles, showing its reusability and durability. Cheng and coworkers investigated the use of pure cotton and cotton/cellulose aerogels derived from pure cotton and cellulose fiber from paper waste for the removal of oil and organic solvents [105]. The cotton/cellulose aerogels exhibited better performance over pure cotton aerogels because of the synergetic effects of two different cellulose fiber sources. The sorption capacity of the cotton/cellulose composite aerogel was 72.3 and 94.3 g/g for machine oil and dichloromethane, respectively [105].

underground storage of CO2 for reuse. However, the success of these CCSU technologies relies on the CO2 adsorption efficiency, manufacturing cost, and ease of handling and regeneration. Solid adsorbents include carbonaceous materials, covalent organic frameworks (COFs), porous organic frameworks (POPs) and metal– organic frameworks (MOFs), metal oxides (alkaline, alkaline earth and transition metals) and mesoporous silica-based materials and amines have been proposed for CCSU technologies [114–116]. Solid adsorbents derived from biopolymers are attracting interest for CCSU technologies because of their unique properties. Recently reported applications of biopolymer-based materials in capturing CO2 gas

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization…

Cellulose Acid blue 93 and methylene blue [80]

Chitin Reactive yellow 2 and Reactive black 5 [84]

silicon oil, pump oil

Chitosan Methylene blue [88]

ethanol, and gasoline

Polysaccharide based biopolymers used in sorption of different pollutants.

Liquid paraffin, pump oil, and xylene

Pollutants References

Malachite green [81] Congo red [82] Red 180, Blue CR 19, and Orange 142 [83] Ag(I) and Sn(II) [95] Pb(II), Cd(II), Ni(II), and Zn(II) [95, 96] Cu(II) [95–97] Hexane, cyclohexane, petroleum ether [104]

Machine oil and dichloromethane [105] CO2 [115, 117–

Methylene blue [85, 86] Indigo carmine [87] Fe(III) and Cu(II) [98] Chloroform, gasoline oil, hexane, toluene, [106]

CO2 [39]

Malachite green [89] Acid red 73 and Pb(II) [99] As(III) and As(IV) [100] Carbon tetrachloride, ethylene glycol, silicon oil, [107]

Diesel [107, 108] Marine diesel [108] CO2 [120, 121]

Ethylene acetate, pump oil, crude oil, acetone,

119]

[107]

are discussed in this section.

composites

Table 1.

17

Biopolymers/biopolymers based

DOI: http://dx.doi.org/10.5772/intechopen.80898

Duan and coworkers prepared hydrophobic and oleophilic methyltrichlorosilane (MTCS) coated-chitin sponges and showed their ability to absorb a wide range of oils and nonpolar organic solvents including chloroform, gasoline oil, hexane, pump oil, silicon oil and toluene from the surface and bottom of the polluted water [106]. They reported that low viscosity organics such as chloroform, gasoline oil, hexane, and toluene could be absorbed to equilibrium within 8 min, whereas higher viscosity oils, such as pump oil and silicon oil could reach the absorption equilibrium within 13 min. MTCS-coated chitin sponges displayed recyclability with at least 10 times with approximately 93% adsorption capacity. Li et al. prepared porous chitosan-oxidized cellulose aerogel as an oil and organic solvent absorbent [107]. They reported the adsorption capacity in the range of 13.77–28.20 g/g for various oils and organic solvents including carbon tetrachloride, ethylene glycol, silicon oil, ethylene acetate, pump oil, crude oil, acetone, ethanol, diesel, and gasoline. Their material was stable over 50 absorptiondesorption cycles following a pseudo-second-order kinetic model. The utilization of N,O-carboxymethyl chitosan for the adsorption of Marine Diesel, Diesel and Marine-2T oil for oil spill treatment has been reported by Doshi and coworkers [108].

#### 5.4 Carbon dioxide adsorption

Carbon dioxide (CO2) is the primary greenhouse gas (GHG) emitted through human activities and also considered as one of the major contributors to the greenhouse effect and global warming. CO2 emissions, primarily from fossil fuel based power plants account for over 87% of the global annual emission of CO2 [109]. According to the Intergovernmental Panel (IPCC) Fifth Assessment Report, the industrial revolution has significantly contributed to the raised atmospheric CO2 levels from 280 to 400 parts per million (ppm) in the last 150 years [110]. It is estimated that by the end of year 2030, the global GHG emission could rise by 25– 90% as compared to the GHG level in 2000, reaching CO2 atmospheric levels in the range of 600–1550 ppm [111]. Some long-term effects of global warming include higher temperatures, changing rainfall patterns, rising sea levels, severe weather events ranging from flash floods, high intense hurricanes, freezing winters, severe droughts and heat waves. Therefore, many approaches including improved energy efficiency and energy conservation, increased utilization of low carbon fuels such as natural gas, hydrogen or nuclear power, usage of renewable energy such as solar, wind and hydropower and bioenergy, application of geoengineering processes such as afforestation and reforestation and use of carbon dioxide capture, storage and utilization (CCSU) techniques are extensively considered and adopted by various countries to mitigate CO2 emissions [112, 113]. Among those, CCSU technologies have received a significant interest due to their ability to control in-situ CO2 emissions from both industrial sources and natural sources. CCSU technologies mainly accompany separation of CO2, transportation of captured and compressed CO2, and

## Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization… DOI: http://dx.doi.org/10.5772/intechopen.80898

underground storage of CO2 for reuse. However, the success of these CCSU technologies relies on the CO2 adsorption efficiency, manufacturing cost, and ease of handling and regeneration. Solid adsorbents include carbonaceous materials, covalent organic frameworks (COFs), porous organic frameworks (POPs) and metal– organic frameworks (MOFs), metal oxides (alkaline, alkaline earth and transition metals) and mesoporous silica-based materials and amines have been proposed for CCSU technologies [114–116]. Solid adsorbents derived from biopolymers are attracting interest for CCSU technologies because of their unique properties. Recently reported applications of biopolymer-based materials in capturing CO2 gas are discussed in this section.


#### Table 1.

Polysaccharide based biopolymers used in sorption of different pollutants.

(DMF), were tested and MHPCA showed oil absorption capacity in the range of 59–136 g/g. MHPCA exhibited magnetically driven oil absorption and elasticity after 30 compression-release cycles, showing its reusability and durability. Cheng and coworkers investigated the use of pure cotton and cotton/cellulose aerogels derived from pure cotton and cellulose fiber from paper waste for the removal of oil

and organic solvents [105]. The cotton/cellulose aerogels exhibited better performance over pure cotton aerogels because of the synergetic effects of two different cellulose fiber sources. The sorption capacity of the cotton/cellulose composite aerogel was 72.3 and 94.3 g/g for machine oil and dichloromethane,

Duan and coworkers prepared hydrophobic and oleophilic methyltrichlorosilane (MTCS) coated-chitin sponges and showed their ability to absorb a wide range of oils and nonpolar organic solvents including chloroform, gasoline oil, hexane, pump oil, silicon oil and toluene from the surface and bottom of the polluted water [106]. They reported that low viscosity organics such as chloroform, gasoline oil, hexane, and toluene could be absorbed to equilibrium within 8 min, whereas higher viscosity oils, such as pump oil and silicon oil could reach the absorption equilibrium within 13 min. MTCS-coated chitin sponges displayed recyclability with at least 10 times with approximately 93% adsorption capacity. Li et al. prepared porous chitosan-oxidized cellulose aerogel as an oil and organic solvent absorbent [107]. They reported the adsorption capacity in the range of 13.77–28.20 g/g for various oils and organic solvents including carbon tetrachloride, ethylene glycol, silicon oil, ethylene acetate, pump oil, crude oil, acetone, ethanol, diesel, and gasoline. Their material was stable over 50 absorptiondesorption cycles following a pseudo-second-order kinetic model. The

utilization of N,O-carboxymethyl chitosan for the adsorption of Marine Diesel, Diesel and Marine-2T oil for oil spill treatment has been reported by Doshi and

Carbon dioxide (CO2) is the primary greenhouse gas (GHG) emitted through human activities and also considered as one of the major contributors to the greenhouse effect and global warming. CO2 emissions, primarily from fossil fuel based power plants account for over 87% of the global annual emission of CO2 [109]. According to the Intergovernmental Panel (IPCC) Fifth Assessment Report, the industrial revolution has significantly contributed to the raised atmospheric CO2 levels from 280 to 400 parts per million (ppm) in the last 150 years [110]. It is estimated that by the end of year 2030, the global GHG emission could rise by 25– 90% as compared to the GHG level in 2000, reaching CO2 atmospheric levels in the range of 600–1550 ppm [111]. Some long-term effects of global warming include higher temperatures, changing rainfall patterns, rising sea levels, severe weather events ranging from flash floods, high intense hurricanes, freezing winters, severe droughts and heat waves. Therefore, many approaches including improved energy efficiency and energy conservation, increased utilization of low carbon fuels such as natural gas, hydrogen or nuclear power, usage of renewable energy such as solar, wind and hydropower and bioenergy, application of geoengineering processes such as afforestation and reforestation and use of carbon dioxide capture, storage and utilization (CCSU) techniques are extensively considered and adopted by various countries to mitigate CO2 emissions [112, 113]. Among those, CCSU technologies have received a significant interest due to their ability to control in-situ CO2 emissions from both industrial sources and natural sources. CCSU technologies mainly accompany separation of CO2, transportation of captured and compressed CO2, and

respectively [105].

Advanced Sorption Process Applications

coworkers [108].

16

5.4 Carbon dioxide adsorption

Dassanayake et al. investigated the preparation of activated carbon monoliths derived from cellulose-based aerogel (aerocellulose) and its CO2 adsorption properties at low and ambient temperatures [117]. The activated carbon prepared from aerocellulose exhibited a specific surface area of 753 m<sup>2</sup> /g, a total pore volume of 0.72 cm3 /g, and a micropore volume of 0.27 cm3 /g. The physical CO2 uptakes for these materials were 5.8 mmol/g of CO2 at 0°C and 1 atm and 3.7 mmol/g of CO2 at 25°C and 1.2 atm. They also reported the synthesis and CO2 adsorption of a series of amidoxime (AO)-functionalized microcrystalline (MCC) and nanocrystalline cellulose (NCC)-mesoporous silica composites at ambient and elevated temperatures [115, 118]. They reported the CO2 sorption capacities of MCC-AO composites in the range of 0.40–1.27 and 2.84–3.85 mmol/g at ambient (25°C, 1.2 atm) and elevated temperatures (120°C, 1.0 atm), respectively. Whereas, NCC-AO composites which showed highest CO2 uptakes of 3.30 mmol/g at 25°C (1.2 atm) and 5.54 mmol/g at 120°C (1 atm), respectively. Both MCC-AO and NCC-AO composites displayed a good recyclability and stability after 10 successive adsorption/desorption cycles with negligible losses of the sorption capacity. Shehaqui et al. reported the direct CO2 capture from air onto nanofibrillated cellulose (NFC)-polyethylenimine (PEI) foams [119]. They demonstrated the impact of both PEI and relative humidity (RH) on the CO2 capture under atmospheric conditions with CO2 concentration of 400 ppm. At 80% RH and PEI content of 44 wt%, a CO2 uptake of 2.22 mmol/g was achieved with a stability over five repetitive cycles.

Dassanayake and coworkers also studied the CO2 adsorption on activated carbon prepared by carbonization and KOH activation of chitin aerogels [39]. Their material showed CO2 adsorption capacities of 5.02 mmol/g at 0°C and 3.44 mmol/g at 25° C under ambient pressure of 1 atm. Eftaiha et al. investigated the CO2 adsorption by a chitin-acetate (CA)/dimethyl sulfoxide (DMO) binary system and reported the CO2 uptake of 3.63 mmol/g at 3.95 atm and 0°C [120]. Fujiki and Yogo investigated CO2 adsorption capacities of nitrogen-doped activated carbons prepared from chitosan at two different pressure conditions; namely 0.15 and 0.99 atm at 25°C [121]. They reported CO2 adsorption capacities of 1.6 mmol/g at 0.15 atm and 4.9 mmol/g at 0.99 atm for their material. Alhwaige et al. reported the preparation of montmorillonite (MMT) reinforced bio-based chitosan-polybenzoxazine (CTS-PBZ) composite carbon aerogels and their ability to capture CO2 [122]. MMT-CTS-PBZ composite carbon aerogels showed a maximum CO2 adsorption of 5.72 mmol/g with multi-cyclic adsorption-desorption stability.

Table 1 summarizes the main applications of biopolymer-based materials for pollutants removal from water and sorption of CO2.

Author details

19

Rohan S. Dassanayake, Sanjit Acharya and Noureddine Abidi\*

\*Address all correspondence to: noureddine.abidi@ttu.edu

Texas Tech University, Lubbock, TX, USA

provided the original work is properly cited.

Department of Plant and Soil Science, Fiber and Biopolymer Research Institute,

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization…

DOI: http://dx.doi.org/10.5772/intechopen.80898

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

## 6. Conclusion

Biopolymers and biopolymer-based materials have been widely investigated for various sorption applications due to their excellent adsorption capacities, easy functionalization, relative abundance, green, sustainable, biodegradable, low cost, and environmental benign properties. In this chapter, we presented the properties, processing, characterization and sorption applications of three most commonly studied natural polysaccharides, namely cellulose, chitin and chitosan. Recent developments of cellulose, chitin and chitosan-based materials in organic dye removal, heavy metals removal, oil and solvent spillage cleanup, and CO2 adsorption have been extensively discussed.

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization… DOI: http://dx.doi.org/10.5772/intechopen.80898
