*Innovative Separation Technology Utilizing Marine Bioresources: Multifaceted Development… DOI: http://dx.doi.org/10.5772/intechopen.95839*

**Matrix body**

**212**

**chitosan** **chitosan/PAM c**

**Rayon fibers coated**

*NA*

> **with chitosan**

**chitosan** **chitosan** **chitosan** **chitosan** **chitosan** **chitosan** *N***-allylthiourea**

*NA*

**chitosan**

**chitosan** **chitosan** **chitosan** **oleoyl chitosan**

*NA*

**EDTA**

**d-silane/mGO E**

**GA a**

*NA*

**CNTsD**

**Fe**

**O3 4**

**bentnite, cobalt oxide**

**CB[8] w**

**CA-CD s**

**PDMAEMA p**

**graphene nanopalates**

*NA*

**EDTA d**

*NA*

**Additional adsorbent**

**Cross-linker**

**GA a, EGDE b**

**MBA e**

**PBf**

**CIT g, TPP h, SSA i, OAj, ECH k, GAa**

**TTE l, EGDE b**

**GA a**

*NA*

**EDC t, NHSu**

*NA* *NA* *NA* *NA* *NA*

**,**

**spherical beads**

**spherical beads**

**magnetic**

**batch**

**AG25 q, RB19r**

**[73]**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

**adsorption**

**spherical beads**

**particles**

**powder** **powder** **powder** **magnetic**

**batch**

**AB C**

**[78]**

**adsorption**

**spherical beads**

**particles** **magnetic**

**batch**

**Pb(II), Cd(II)**

**[25]**

**adsorption**

**spherical beads**

**nanoparticles**

 **batch**

**Fe(II)**

**[11]**

**adsorption**

**batch**

**phenol**

**[23]**

**adsorption**

**batch**

**AS(III)B**

**[74]**

**adsorption**

**batch**

**CR A, Cr(VI)**

**[21]**

**adsorption**

**batch**

**Pb, RO5 x, AB25 y**

**RY145 z**

**,**

**[84] 2019**

**adsorption**

**through packed**

**RB49 v**

**[77]**

**column**

 **batch**

**MOn, AR1 o**

**[66] 2018**

**adsorption**

 **batch**

**RB5**

**m**

**[49]**

**adsorption**

**Type of**

**Adsorption**

**Target substances**

 **Ref. Year**

**process**

**adsorbent media**

**spherical beads**

**cylindrical**

**batch**

**Cu(II), Pb(II), Cd(II)**

 **[75] 2017**

**adsorption**

**tablets**

**rayon fibers**

 **batch**

**Cs**

**[76]**

**adsorption**

 **through packed**

**Cu(II), Pb, Zn(II),** *E.*

**[28] 2016**

> *coli, S. aureus*

**bed**

(*C*<sup>e</sup> [mol g�<sup>1</sup> ]) using the Langmuir adsorption isotherm (Eq. 5). The Langmuir isotherm explains both monolayer and homogeneous adsorption.

$$q\_{\epsilon} = \frac{Q\_{\text{max}} \text{ K C}\_{\epsilon}}{1 + K \text{ C}\_{\epsilon}} \tag{5}$$

Li and co-workers have prepared chitosan fibrous membrane and investigated the dynamic flow adsorption using filtration apparatus for removal of Cr (VI) from aqueous phase [14]. The study revealed the flow adsorption is advantageous than static batch adsorption for small concentration of feed Cr (VI). In addition, the flow rate of feed solution during the flow process directly influenced on the adsorption behavior. Lower flow rate increases the adsorbed amount of Cr (VI) nearly up to maximum adsorption capacity since the contact time between adsorbent and

*Innovative Separation Technology Utilizing Marine Bioresources: Multifaceted Development…*

Separation performance is strongly depended on the membrane structure as well as selection of absorbent. Khajavian and co-workers have demonstrated the removal of Malachite Green known as a cationic dye *via* flow process using chitosan/poly (vinyl alcohol) incorporating metal–organic frameworks (ZIF-8) [80]. The physical factors including membrane thickness and porous structure generated by pore generator (polyethylene glycol) inside membrane regulate water flux and dye rejection. The chitosan membrane adopting flow processes should be optimized for

**Table 3** shows the recent studies of adsorption processes using chitosan or its derivatives. Here, the adsorption studies in membrane-type process, which were

A spherical bead is the basis of the adsorbent media. Chitosan beads can be obtained easily *via* droplet method which a small portion of chitosan dissolved in acid solution is dropped to alkaline solution for neutralization. Bead-type absorbents can be applied to packed bed adsorption operated in a flow process [28]. Adsorbents composed of chitosan and its derivatives incorporated with inorganic substances have been developed to enhance adsorption performance [21, 75, 78, 84]. In addition, it is a notable trend that the studies about the removal of

As a very recent approach, Sadiq and coworkers developed chitosan beads incorporating with deep eutectic solvents (DES) which are prepared from choline chloride with urea or glycerol for removing organic dye [79]. The DES is paid attention to possess biocompatibility and low toxicity regardless of similar charac-

Highly porous media from chitosan gel which have large surface area contribut-

Chitosan aerogel prepared with GA has highly porous structure showed by a field emission scanning electron microscopy (FE-SEM) (**Figure 8a**). The chitosan aerogel prepared with GA adsorbed anionic dye (Methyl Orange: 327 Da) rapidly although cationic dye of similar molecular weight (Methylene Blue: 320 Da) is not removed from their aqueous solutions (**Figure 8b**). Selective removal of anionic substrates in high adsorption rate can be achieved by static attraction derived

ing high adsorption ability have been developed recently [87–91]. Such highly porous media are frequently called aerogel. Chitosan aerogels can be prepared *via* freeze-drying of chitosan aqueous solution and stabilization using cross-linker, such as glutaraldehyde (GA). Yi and coworkers reported chitosan aerogel silylated with methyl trimethoxysilane which has spring-like structure leading to high oil absorption [89]. Yu and coworkers revealed preparation of chitosan aerogel incorporating graphene oxide and montmorillonite without cross-linker exhibited efficiently Cr

adsorbate increases.

each system and target substances.

*DOI: http://dx.doi.org/10.5772/intechopen.95839*

already showed in **Table 2** are eliminated.

organic dye from aqueous are clearly increasing.

teristics with ionic liquids [79, 85, 86].

**4.3 Highly porous aerogels**

(VI) adsorption [88].

**215**

**4.2 Other types of absorbent media composed of chitosan**

Where, *Q*max and *K* are the maximum adsorption capacity [mol g�<sup>1</sup> ] and the equilibrium adsorption constant [L mol�<sup>1</sup> ], respectively. **Figure 7a** displays the effect of the mass fraction of immobilized PB in chitosan membrane (*MFPB*) on the maximum adsorption capacity for the membrane and for the PB immobilized in membranes. Immobilization in the chitosan membrane achieved to improve cesium adsorption without inhibition of the adsorption ability of PB.

The diffusivity of adsorbate molecules in adsorbent media strongly influences the adsorption rate [81]. The effective diffusion coefficient (*Deff* [m2 s �1 ]) of cesium ions in the chitosan membrane immobilizing PB was determined according to the mass transfer theory. **Figure 7b** depicts the effect of *MFPB* on the *Deff* of cesium ions in the initial period of isothermal adsorption. The obtained values of *Deff* were lower than that of the diffusion coefficient in the bulk aqueous phase, which was previously reported as 2.17 � <sup>10</sup>�<sup>9</sup> <sup>m</sup><sup>2</sup> <sup>s</sup> �<sup>1</sup> [82]. The structure of the membrane consisting of a chitosan polymer chain and PB were observed to suppress the diffusion of cesium ions into the membrane. The diffusion of cesium ions was inhibited considerably by the immobilized PB, which became dominant in comparison to the mass transfer resistance by the chitosan polymer chain [20].

#### *4.1.2 Adsorbed separation in flow process*

The adsorbed separation in flowing process through the membrane immobilizing adsorbents is more efficiently than equilibrium adsorption in flask. Owing to the adsorption ability collaborated with molecular size screening ability, selective separation is exhibited higher than without adsorbent system. Moreover, adsorption capability of adsorbents is fully utilized in the adsorption in combination with filtration in a flow process whereas the batch adsorption is up to equilibrium by the decrease of solutes concentration in liquid phase [83].

#### **Figure 7.**

*Effect of the mass fraction of PB on (a) the maximum adsorption capacity for the chitosan membrane (left axis) and for the PB immobilized in the membrane (right axis). (b) the effective diffusion coefficient of cesium ions in the initial period of isothermal adsorption (25°C). Reprinted from Fujisaki, Kashima, Hagiri, Imai [20] with permission from WILEY-VCH.*

*Innovative Separation Technology Utilizing Marine Bioresources: Multifaceted Development… DOI: http://dx.doi.org/10.5772/intechopen.95839*

Li and co-workers have prepared chitosan fibrous membrane and investigated the dynamic flow adsorption using filtration apparatus for removal of Cr (VI) from aqueous phase [14]. The study revealed the flow adsorption is advantageous than static batch adsorption for small concentration of feed Cr (VI). In addition, the flow rate of feed solution during the flow process directly influenced on the adsorption behavior. Lower flow rate increases the adsorbed amount of Cr (VI) nearly up to maximum adsorption capacity since the contact time between adsorbent and adsorbate increases.

Separation performance is strongly depended on the membrane structure as well as selection of absorbent. Khajavian and co-workers have demonstrated the removal of Malachite Green known as a cationic dye *via* flow process using chitosan/poly (vinyl alcohol) incorporating metal–organic frameworks (ZIF-8) [80]. The physical factors including membrane thickness and porous structure generated by pore generator (polyethylene glycol) inside membrane regulate water flux and dye rejection. The chitosan membrane adopting flow processes should be optimized for each system and target substances.

#### **4.2 Other types of absorbent media composed of chitosan**

**Table 3** shows the recent studies of adsorption processes using chitosan or its derivatives. Here, the adsorption studies in membrane-type process, which were already showed in **Table 2** are eliminated.

A spherical bead is the basis of the adsorbent media. Chitosan beads can be obtained easily *via* droplet method which a small portion of chitosan dissolved in acid solution is dropped to alkaline solution for neutralization. Bead-type absorbents can be applied to packed bed adsorption operated in a flow process [28].

Adsorbents composed of chitosan and its derivatives incorporated with inorganic substances have been developed to enhance adsorption performance [21, 75, 78, 84]. In addition, it is a notable trend that the studies about the removal of organic dye from aqueous are clearly increasing.

As a very recent approach, Sadiq and coworkers developed chitosan beads incorporating with deep eutectic solvents (DES) which are prepared from choline chloride with urea or glycerol for removing organic dye [79]. The DES is paid attention to possess biocompatibility and low toxicity regardless of similar characteristics with ionic liquids [79, 85, 86].

#### **4.3 Highly porous aerogels**

Highly porous media from chitosan gel which have large surface area contributing high adsorption ability have been developed recently [87–91]. Such highly porous media are frequently called aerogel. Chitosan aerogels can be prepared *via* freeze-drying of chitosan aqueous solution and stabilization using cross-linker, such as glutaraldehyde (GA). Yi and coworkers reported chitosan aerogel silylated with methyl trimethoxysilane which has spring-like structure leading to high oil absorption [89]. Yu and coworkers revealed preparation of chitosan aerogel incorporating graphene oxide and montmorillonite without cross-linker exhibited efficiently Cr (VI) adsorption [88].

Chitosan aerogel prepared with GA has highly porous structure showed by a field emission scanning electron microscopy (FE-SEM) (**Figure 8a**). The chitosan aerogel prepared with GA adsorbed anionic dye (Methyl Orange: 327 Da) rapidly although cationic dye of similar molecular weight (Methylene Blue: 320 Da) is not removed from their aqueous solutions (**Figure 8b**). Selective removal of anionic substrates in high adsorption rate can be achieved by static attraction derived

(*C*<sup>e</sup> [mol g�<sup>1</sup>

]) using the Langmuir adsorption isotherm (Eq. 5). The Langmuir

(5)

] and the

]) of cesium

�1

], respectively. **Figure 7a** displays the

�<sup>1</sup> [82]. The structure of the membrane consisting

*qe* <sup>¼</sup> *Qmax K Ce* 1 þ *K Ce*

effect of the mass fraction of immobilized PB in chitosan membrane (*MFPB*) on the maximum adsorption capacity for the membrane and for the PB immobilized in membranes. Immobilization in the chitosan membrane achieved to improve cesium

The diffusivity of adsorbate molecules in adsorbent media strongly influences

ions in the chitosan membrane immobilizing PB was determined according to the mass transfer theory. **Figure 7b** depicts the effect of *MFPB* on the *Deff* of cesium ions in the initial period of isothermal adsorption. The obtained values of *Deff* were lower than that of the diffusion coefficient in the bulk aqueous phase, which was previ-

of a chitosan polymer chain and PB were observed to suppress the diffusion of cesium ions into the membrane. The diffusion of cesium ions was inhibited considerably by the immobilized PB, which became dominant in comparison to the mass

The adsorbed separation in flowing process through the membrane immobilizing adsorbents is more efficiently than equilibrium adsorption in flask. Owing to the adsorption ability collaborated with molecular size screening ability, selective separation is exhibited higher than without adsorbent system. Moreover, adsorption capability of adsorbents is fully utilized in the adsorption in combination with filtration in a flow process whereas the batch adsorption is up to equilibrium

*Effect of the mass fraction of PB on (a) the maximum adsorption capacity for the chitosan membrane (left axis) and for the PB immobilized in the membrane (right axis). (b) the effective diffusion coefficient of cesium ions in the initial period of isothermal adsorption (25°C). Reprinted from Fujisaki, Kashima, Hagiri, Imai [20] with*

Where, *Q*max and *K* are the maximum adsorption capacity [mol g�<sup>1</sup>

isotherm explains both monolayer and homogeneous adsorption.

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

adsorption without inhibition of the adsorption ability of PB.

transfer resistance by the chitosan polymer chain [20].

by the decrease of solutes concentration in liquid phase [83].

the adsorption rate [81]. The effective diffusion coefficient (*Deff* [m2 s

equilibrium adsorption constant [L mol�<sup>1</sup>

ously reported as 2.17 � <sup>10</sup>�<sup>9</sup> <sup>m</sup><sup>2</sup> <sup>s</sup>

*4.1.2 Adsorbed separation in flow process*

**Figure 7.**

**214**

*permission from WILEY-VCH.*

from several micrometers down to tens of nanometers have useful properties such

*Innovative Separation Technology Utilizing Marine Bioresources: Multifaceted Development…*

In particular, chitosan nanofiber can be expected as an alternative to air filter media (**Figure 9**). The particle collection performance across chitosan nanofiber media decreased with increase in the amount of chitosan nanofibers on the polyethylene terephthalate (PET) non–woven, as shown in **Figure 10**. In addition, it was

as high specific surface area, porosity, as well as biocompatibility [93, 94]. Nanofibers made from chitosan have not yet been fully established as compared with other nanofibers [95–97]. Chitosan nanofibers have diameter around 10 nm and amino groups on its surface with positive charge [98]. Accordingly, chitosan nanofibers possess unique characteristics and advantages that other nanofiber does not have, that has been expected to be used in various sorts of industrial fields, for instance, filtrations, recovery of metal ions, adsorption of proteins, drug release, enzyme carriers, wound healing, cosmetics, and biosensors have been developed

*DOI: http://dx.doi.org/10.5772/intechopen.95839*

[99–106].

**Figure 9.**

**Figure 10.**

**217**

*SEM photograph of chitosan nanofibers filter media.*

*Comparison of the fractional penetrations of various sorts of test filter media.*

**Figure 8.**

*Chitosan aerogel prepared with glutaraldehyde as a cross-linker. (a) Morphology observed by FE-SEM. (b) Isothermal adsorption of anionic dye (methyl Orange) and cationic dye (methylene blue) onto chitosan aerogel.*

abundant amine and sufficient surface area. Moreover, chitosan aerogel can immobilize various functional particles hence it is expected to develop as new adsorbent media [88, 90].
