**3. Filtration processes with sieving to molecules**

**Table 1** summarizes the recent studies of a filtration membrane consisting of chitosan or chitosan derivatives. In several membranes, the functional materials are additionally composed to improve the separation ability. The relevant studies are picked up and described below.


**3.1 Nanofiltration**

*a*

*b*

*c*

*d*

*e*

*f*

*g*

*h*

*i*

*j*

*k*

*l*

*n*

*o*

*p*

*q*

*r*

*s*

*t*

*u*

**Table 1.**

*PSF: polysulfone*

**Membrane body Additive functionalizing material**

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

*DMFCs: direct methanol fuel cells*

*MOF: metal organic frameworks*

*PVDF: polyvinylidene fluoride*

*PTFE: polytetrafluoroethylene*

*TEOS: tetraethyl orthosilicate*

*PVA: polyvinyl alcohol*

*PAN: polyacrylonitrile*

*MB: Methylene Blue (dye) mMO: Methyl Orange (dye)*

*AYR: Alizarine Yellow (dye)*

*DB38: Direct Black 38 (dye)*

*XO: Xylenol Orange (dye)*

*MG: Malachite Green (dye)*

*GA: glutaraldehyde*

*PS: Ponceau S (dye)*

*PES: polyethersulfone*

*IPA: isopropanol*

*MWNT: multi-walled carbon nanotubes*

*PEGDE: polyethyleneglycol diglycidyl ether*

*Cu-BTC: copper-1,3,5-benzenetricarboxylic acid*

*Recent studies of a separation membrane consisting of chitosan.*

**chitosan** *NA* **succinic**

**3.2 Gas separation**

**209**

**3.3 Hydrophilicity-based process**

As a common procedure, many types of chitosan-based membranes are prepared using the casting method. Chitosan membranes prepared by the casting method usually has a highly compacted gel structure since hydrogen bonding derived from a lot of hydroxyl groups. The dense membranes are beneficial for the nanofiltration process separating small substances, for instance, salts, organic acids, or organic dyes [41, 43, 50–54]. For improving the separation ability, combination of organic–inorganic polymeric hybrid membrane is an innovative approach. Metal–organic frameworks (MOFs) were incorporated into the chitosan polymeric matrix to obtain a positively charged membrane surface for cation removal [50]. Montmorillonite clay, which is dispersed uniformly in a porous matrix, enhances chromium removal [53]. Also, carbon nanotubes are combined with the chitosan membrane for improving solution permeability and salt rejection [51, 55].

**Crosslinker**

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

**acid**

**Target substances**

**H2O (vapor)** **Expected application**

**packaging film**

**Ref. Year**

**[63] 2021**

The chitosan membranes with dense polymeric structures can also be used for gas separation processes. It is reported that a chitosan/polyvinyl alcohol (PVA)-blended membrane exhibited high air filtration with antibacterial activity [56]. Nowadays, CO2 separation technology has caught attention due to the increase in concerns related to climate change because of greenhouse gases. Chitosan-based membranes for CO2 separation membranes are developed to immobilize active sites, such as copper-1,3,5-benzenetricarboxylic acid (Cu-BTC) [57] and hydrotalcite [58].

Due to a high hydrophilicity derived from abundant hydroxyl groups in glucos-

amine units, the polymeric membranes consisting of chitosan are suitable for

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


#### **Table 1.**

**3. Filtration processes with sieving to molecules**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

**chitosan phosphotungstic acid** *NA* **proton,**

**chitosan/PSF<sup>b</sup> MOFs<sup>c</sup>** *NA* **NaCl,**

**chitosan/PTFE <sup>g</sup>** *NA* **TEOS <sup>h</sup> methanol,**

**chitosan MWNT<sup>d</sup>** *NA* **NaCl,**

**chitosan, phosphorylated chitosan, glycidolmodified chitosan, or sulphated chitosan**

**chitosan MWNT<sup>d</sup> glycerin,**

**chitosan/PVA <sup>i</sup>** *NA* **adipic**

**chitosan polyester nonwoven fabric**

**PVA <sup>i</sup> microparticles of**

picked up and described below.

**carboxymethyl chitosan/PVDF <sup>f</sup>**

**phosphorylated chitosan/PAN <sup>j</sup>**

**phosphorylated chitosan**

**carboxymethyl chitosan/ polyamidoamine**

**chitosan/ methoxy pectin**

**208**

**Membrane body Additive functionalizing material**

**Table 1** summarizes the recent studies of a filtration membrane consisting of chitosan or chitosan derivatives. In several membranes, the functional materials are additionally composed to improve the separation ability. The relevant studies are

> **Crosslinker**

**PEGDE<sup>e</sup>**

**acid**

**sulfuric acid**

**chitosan/PVA <sup>i</sup> motmorillonite** *NA* **Cr(VI) nanofiltration [53**

**graphene oxide GA <sup>k</sup> DB38 <sup>o</sup>**

**chitosan/PVA <sup>i</sup> Cu-BTC <sup>u</sup>** *NA* **CO2 (gas) CO2**

**cutin glycerol H2O**

**chitosan/PES <sup>r</sup> MWNT<sup>d</sup>** *NA* **MG <sup>s</sup> nanofiltration [54] chitosan** *NA* **genipin IPA <sup>t</sup> pervaporation [44]**

**hydrotalcite** *NA* **CO2 (gas) CO2**

*NA NA* **humic**

*NA* **GA <sup>k</sup> MgCl2**

**Target substances**

**methanol**

**MgCl2, CaCl2, Na2SO4**

**NaCl, MgCl2 MgSO4**

**acid**

**toluene**

**Na2SO4 MB <sup>l</sup> MO m, AYR <sup>n</sup>**

**H2O (vapor)**

**MgSO4**

**p , XO <sup>q</sup>**

**(vapor)**

**GA <sup>k</sup> ethanol pervaporation [42]**

**, PS**

**NaCl aerosol** **Expected application** **Ref. Year**

**DMFCs <sup>a</sup> [60] 2016**

**nanofiltration [50] 2017**

**nanofiltration [51]**

**nanofiltration [52]**

**air filtration [56]**

**nanofiltration [41]**

**membrane drier**

**pervaporation [46] 2018**

**nanofiltration [55] 2020**

**nanofiltration [43]**

**[57]**

**[58]**

**[62]**

**separation**

**separation**

**packaging film**

**[61] 2019**

*Recent studies of a separation membrane consisting of chitosan.*

#### **3.1 Nanofiltration**

As a common procedure, many types of chitosan-based membranes are prepared using the casting method. Chitosan membranes prepared by the casting method usually has a highly compacted gel structure since hydrogen bonding derived from a lot of hydroxyl groups. The dense membranes are beneficial for the nanofiltration process separating small substances, for instance, salts, organic acids, or organic dyes [41, 43, 50–54]. For improving the separation ability, combination of organic–inorganic polymeric hybrid membrane is an innovative approach. Metal–organic frameworks (MOFs) were incorporated into the chitosan polymeric matrix to obtain a positively charged membrane surface for cation removal [50]. Montmorillonite clay, which is dispersed uniformly in a porous matrix, enhances chromium removal [53]. Also, carbon nanotubes are combined with the chitosan membrane for improving solution permeability and salt rejection [51, 55].

#### **3.2 Gas separation**

The chitosan membranes with dense polymeric structures can also be used for gas separation processes. It is reported that a chitosan/polyvinyl alcohol (PVA)-blended membrane exhibited high air filtration with antibacterial activity [56]. Nowadays, CO2 separation technology has caught attention due to the increase in concerns related to climate change because of greenhouse gases. Chitosan-based membranes for CO2 separation membranes are developed to immobilize active sites, such as copper-1,3,5-benzenetricarboxylic acid (Cu-BTC) [57] and hydrotalcite [58].

#### **3.3 Hydrophilicity-based process**

Due to a high hydrophilicity derived from abundant hydroxyl groups in glucosamine units, the polymeric membranes consisting of chitosan are suitable for

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