**4. Adsorption processes**

Adsorption is frequently used in separation processes to recover worthy substances as well as water treatment due to its advantages, such as easy operation, high selectivity, and low operational costs [66, 67]. **Tables 2** and **3** summarize the recent studies of adsorption processes, which employed chitosan or chitosan derivatives as either main body of adsorbent or immobilizing media for other adsorbents (mainly fine particles).

As shown in **Figure 1**, chitosan has abundant functional groups. Thereby, chitosan and its derivatives also show adsorbent capabilities with various metal ions and organic substances depending on the pH and the concentration of ionic substances [13]. Hence, their adsorption properties are being widely researched [68]. A large portion of the study employed chitosan and its derivatives for adsorption processes devoted to remove heavy metal from polluted water [11, 13–16, 28, 69– 71]. Considering organic compounds, chitosan can adsorb anionic dyes due to amine groups in a chitosan polymer chain [72–74]. It has been reported that nonionic compounds like naphthalene [22] are also adsorbed on chitosan. For improving the adsorption ability, fibrous membranes are fabricated to remove ionic substances or heavy metal ions [12–16, 71]. Fibrous membranes with the adsorption ability are beneficial due to not only large surface area but also high permeation flux. Chitosan gel have shown brilliant abilities as immobilizing media to various adsorbent substances not only to enhance absorption performance but also to enlarge coverage of adsorbates [20–21, 23, 25, 66, 73, 75–79].

Adsorption processes are liberally categorized into two types which are adsorption conducted in a batch process and adsorption in combination with filtration in a flow process.

#### **4.1 Membrane-type absorbents adapting with filtration process**

Chitosan have been focused as the media immobilizing various adsorbents since it is able to form stable gel structure through pH responsible [15, 20, 24, 71, 80]. From the advantages in both the adsorption process with selectivity and filtration with continuous operation, the membrane-type adsorbents have been recently developed to adopt the flow process. **Table 2** summarizes the studies of membranetype adsorbents consisted of chitosan or chitosan derivatives.

#### *4.1.1 Characterization of chitosan membrane immobilizing adsorbent in batch process*

For a large portion of such studies, adsorption abilities are evaluated from isothermal adsorption in batch process to reveal adsorption mechanisms [24, 72]. As a typical case of an adsorption membrane immobilizing adsorbent particles, chitosan membrane incorporating Prussian Blue (PB) was developed for cesium

removal from the aqueous phase [20]. The maximum adsorption capacity can be evaluated from the equilibrium adsorption amount of absorbate on absorbent

**Membrane body Membrane type Additional**

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

**chitosan affinity membrane multilayered**

**immobilizing adsorbents**

**immobilizing adsorbents**

**immobilizing adsorbents**

**chitosan dense membrane**

**chitosan/PVA<sup>a</sup> dence membrane**

**chitosan/PVA <sup>a</sup> dence membrane**

**chitosan/ polyester**

**chitosan/ polyacrylonitrile**

**PVA<sup>a</sup>**

**octyl-**

**PEI<sup>m</sup>**

*a*

*b*

*c*

*d*

*e*

*f*

*h*

*i*

*j*

*k*

*l*

*n*

*o*

**211**

**Table 2.**

**chitosan/ polyamide6**

**oxidized chitosan/**

**trimethoxysilane modified chitosan**

**chitosan/PVA<sup>a</sup> /**

*PVA: poly(vinyl alcohol)*

*CNTs: carbon nanotubes*

*GA: glutaraldehyde*

*TEOS: tetraethyl orthosilicate*

*PET: polyethylene terephthalate*

*MOF: metal–organic frameworks <sup>g</sup> PB: Prussian Blue (dye used as adsorbent)*

*RO16: Reactive Orange 16 (dye)*

*PHMG: poly-hexamethylene guanidine*

*ZIF-8: zeolitic imidazole framework-8*

*MO: Methyl Orange (dye)*

*MG: Malachite Green (dye) mPEI: polyethyleneimine*

*BSA: bovine serum albumin*

*PVDF: polyvinylidene fluoride*

**adsorbent**

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

**chitosan/PETe fibrous membrane** *NA* **GA <sup>d</sup> Cu(II), Pb(II),**

**fibrous membrane zirconium MOF f**

**chitosan** *NA NA* **glyoxal RO16h**

**chitosan/PVDF<sup>n</sup> fibrous membrane ZIF-8 <sup>k</sup>** *NA* **BSAo**

*Recent studies of adsorption membrane consisted of chitosan or its derivatives.*

**chitosan/PVA<sup>a</sup> porous membrane CNTs<sup>b</sup> TEOS <sup>c</sup> naphthalene [22] 2015**

**chitosan/cellulose porous membrane** *NA* **GA <sup>d</sup> Cu(II) [69] 2018**

**molecularly imprinted**

**Crosslinker**

**fibrous membrane** *NA* **GA <sup>d</sup> Cr(VI) [14] 2016**

**Target substances**

**Cd(II), Cr(VI)**

*NA* **Pb(II), Cd(II), Cr(VI)**

**ZIF-8 <sup>k</sup>** *NA* **MG <sup>l</sup> [24] 2020**

**ZIF-8 <sup>k</sup>** *NA* **MG <sup>l</sup> [80]**

**dye**

**extracted artemisinin**

**PB <sup>g</sup>** *NA* **Cs [20]**

**fibrous membrane PHMG <sup>j</sup>** *NA* **Cu(II) [16]**

**dense membrane** *NA* **TEOS <sup>c</sup> impurities from**

**porous membrane** *NA NA* **Cu(II) [70]**

**fibrous membrane** *NA NA* **Acid Fuchsin**

**TEOS <sup>c</sup> artemisinin [47] 2019**

**Ref. Year**

**[13] 2017**

**[15]**

**[48]**

**[12]**

**, MO<sup>i</sup> [72]**

**, Cr(VI) [71]**

]) and the equilibrium concentration of absorbate in aqueous phase

(*q*<sup>e</sup> [mol g<sup>1</sup>


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

#### **Table 2.**

separation between water and organic solvents using pervaporation processes [42, 44, 46, 59]. From its hydrophilicity, the chitosan membrane has also been used as a separation membrane in direct methanol fuel cells (DMFCs) requiring blocking of methanol permeation as well as proton conductivity [60]. Regarding the hydrophilicity of chitosan, removal or blocking of water vapor was tested using a chitosan membrane for a part of a membrane drier apparatus [61] and packaging membrane [62, 63]. As a very recent issue, the interest in biodegradable films for packaging has recently been steadily increasing due to significant concerns on environmental

Adsorption is frequently used in separation processes to recover worthy substances as well as water treatment due to its advantages, such as easy operation, high selectivity, and low operational costs [66, 67]. **Tables 2** and **3** summarize the recent studies of adsorption processes, which employed chitosan or chitosan derivatives as either main body of adsorbent or immobilizing media for other adsorbents

As shown in **Figure 1**, chitosan has abundant functional groups. Thereby, chitosan and its derivatives also show adsorbent capabilities with various metal ions and organic substances depending on the pH and the concentration of ionic substances [13]. Hence, their adsorption properties are being widely researched [68]. A large portion of the study employed chitosan and its derivatives for adsorption processes devoted to remove heavy metal from polluted water [11, 13–16, 28, 69– 71]. Considering organic compounds, chitosan can adsorb anionic dyes due to amine groups in a chitosan polymer chain [72–74]. It has been reported that nonionic compounds like naphthalene [22] are also adsorbed on chitosan. For improving the adsorption ability, fibrous membranes are fabricated to remove ionic substances or heavy metal ions [12–16, 71]. Fibrous membranes with the adsorption ability are beneficial due to not only large surface area but also high permeation flux. Chitosan gel have shown brilliant abilities as immobilizing media to various adsorbent substances not only to enhance absorption performance but also to enlarge coverage of

Adsorption processes are liberally categorized into two types which are adsorption conducted in a batch process and adsorption in combination with filtration in a

Chitosan have been focused as the media immobilizing various adsorbents since it is able to form stable gel structure through pH responsible [15, 20, 24, 71, 80]. From the advantages in both the adsorption process with selectivity and filtration with continuous operation, the membrane-type adsorbents have been recently developed to adopt the flow process. **Table 2** summarizes the studies of membrane-

*4.1.1 Characterization of chitosan membrane immobilizing adsorbent in batch process*

For a large portion of such studies, adsorption abilities are evaluated from isothermal adsorption in batch process to reveal adsorption mechanisms [24, 72]. As

a typical case of an adsorption membrane immobilizing adsorbent particles, chitosan membrane incorporating Prussian Blue (PB) was developed for cesium

**4.1 Membrane-type absorbents adapting with filtration process**

type adsorbents consisted of chitosan or chitosan derivatives.

pollution caused by nonbiodegradable packaging materials [64, 65].

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

**4. Adsorption processes**

(mainly fine particles).

flow process.

**210**

adsorbates [20–21, 23, 25, 66, 73, 75–79].

*Recent studies of adsorption membrane consisted of chitosan or its derivatives.*

removal from the aqueous phase [20]. The maximum adsorption capacity can be evaluated from the equilibrium adsorption amount of absorbate on absorbent (*q*<sup>e</sup> [mol g<sup>1</sup> ]) and the equilibrium concentration of absorbate in aqueous phase


**Matrix body**

**213**

**chitosan**

*aGA:*  *bEGDE: ethylene glycol* 

*cPAM:*  *dEDTA:* 

*eMBA:*  *fPB: Prussian Blue (dye used as adsorbent)*

*gCIT: trisodium citrate*

*hTPP:*  *iSSA: sulfosuccinic*

*jOA: oxalic acid*

*kECH:* 

*lTTE:*  *mRB5: Reactive Black 5 (dye)*

*nMO: Methyl Orange (dye)*

*oAR1: Acid Red 1 (dye)*

*pPDMAEMA:*

*qAG25: Acid Green 25 (dye)*

*rRB19: Reactive Blue (dye)* *sCA-CD: citric acid modified*

*tEDC:*  *uNHS:*  *vRB49: Reactive Blue (dye)*

*wCB[8]: cucurbit [8] uril*

*xRO5: Reactive Orange 5 (dye)*

*yAB25: Acidic Blue 25 (dye)* *zRY145: Reactive Yellow 145 (dye)*

*ACR: Congo Red (dye)* *BAS(III): Arsenazo III (dye)*

*CAB: Acid Blue (dye)* *DCNTs: carbon nanotubes* *EmGO: magnetic graphene oxide*

*FDES: deep eutectic solvents*

*GMG: Malachite Green (dye)*

**Table 3.** *Recent studies of adsorption*

 *processes using chitosan or its derivatives*

 *(without* 

*membrane-type*

 *processes).*

*N-hydroxysuccinimide*

*β-cyclodextrin* *3-(3-dimethylaminopropyl)-1-ethylcarbodiimide*

*hydrochloride*

*poly(2-(dimethylamino)ethyl*

 *meth&\$\$\$;*

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

*epichlorohydrin*

*trimethylpropane*

 *triglycidyl ether*

*tripolyphosphate*

 *acid*

*ethylenediaminetetra-acetic*

*N,N-methylenebis(acrylamide)*

 *acid*

*polyacrylamide*

*diglycidylether*

*glutaraldehyde*

**DES F (choline chloride + urea or chline**

**chloride + glycerol)**

**Additional adsorbent**

**Cross-linker**

*NA*

**Type of**

**Adsorption**

**Target substances**

 **Ref. Year**

**process**

**adsorbent media**

**spherical beads**

 **batch**

**MG G**

**[79] 2020**

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

**adsorption**

#### *Chitin and Chitosan - Physicochemical Properties and Industrial Applications*


**Table 3.** *Recent studies of adsorption processes using chitosan or its derivatives (without membrane-type processes).*
