**2. Experimental**

#### **2.1 Sample preparation**

Chitin films were prepared with the purified chitin of under 5% of deacetylation degree, obtained from crab (Sugino Machine Limited). This purified 2%(w/v) chitin slurry was well dispersed in distilled water and the chitin sheets were prepared by suction filtration using Teflon membrane filter (ADVANTEC, Co.) [8–10]. **Figure 2** shows the photograph of the chitin film. The thickness of the film is approximately 0.07 mm.

The chitin fiber specimens were prepared by purifying chitin obtained from the tendon of crab's legs. Based on the article of Prosky *et al.*, the purification

**167**

*Proton Conductivity in Chitin System*

**Figure 2.**

*Photograph of chitin sheet [11].*

*DOI: http://dx.doi.org/10.5772/intechopen.96799*

0.1 L/min and 0.25 L/min, respectively [8].

**2.3 Impedance and water contents measurements**

content *n* was calculated using the following equation,

method was performed using a group of enzymes including α-amylase and protease obtained from *Streptomyces griseus* (Wako Pure Chemical Industries, Ltd.) [8–10]. The oriented chitosan was prepared by oriented chitin to deacetylation treatment

**Figure 3** shows the shape of the fuel cell based on the chitin electrolyte. As show in **Figure 3**, the chitin electrolyte was inserted between Pt-C electrodes (anode and cathode). The current was collected from the current collector plates. The hydrogen and oxygen gases were introduced from the up and down sides of the fuel cell, respectively. In the fuel gas flow, the relative humidity, temperature and gas-flow ratio were controlled by the humidified gas-flow control system of Auto PEM (Toyo Corporation) at room temperature. The H2 gas flow rate and the air flow rate are

The water contents were measured from the relative humidity dependence of the weight of chitin using the electronic analytical balance (OHAUS Inc.) and the number of water molecules per a chitin molecule was calculated from the obtained water contents and molecular weights of water and mono-chitin [8]. The water

> ( )/ / *w d Mw*

This time, *w* and *d* show each weight of wet and dry sample. *Mw* is molecular

*d Mc*

The measurement of electrical conductivity was carried out using precision LCR meter (E4980A, Agilent Technologies Inc.). The relative humidity and temperature were con-trolled by the humidified gas-flow control system (Auto PEM). In the impedance measurement, the electrical conductivities perpendicular to the surface and parallel to the surface in chitin sheet were measured. In the case of chitin fiber specimens, impedance measurements were performed for specimens along the fiber

<sup>−</sup> <sup>=</sup> (1)

*n*

direction and normal to the fiber direction, respectively [8–10].

weight of water. *Mc* is molecular weight of mono-chitin or mono-chitosan.

with 25%(w/v) sodium hydroxide under reflux conditions for 5 hours.

**2.2 Fabrication of the fuel cell based on chitin and operating condition**

*Proton Conductivity in Chitin System DOI: http://dx.doi.org/10.5772/intechopen.96799*

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

However, there were few reports in the field of energy such as using chitin in fuel cells. Biomaterials such as DNA, protein and polysaccharide are abundant in nature, and they are disassembled in environment by microbial. Active use of biomaterials is expected to have less environmental impact and manufacturing

*Schematic diagram of fuel cell used for demonstration (left) and photograph of turning up LED lamp by chitin* 

We have revealed that the chitin is proton conductor and available for electrolyte of fuel cells (**Figure 1**) [8]. Moreover, it was found that appearance of proton conductivity in chitin demand water molecules, and the acetyl group plays important role in injection water molecule into chitin. These suggestions are basis on relationship between results of impedance measurement and water content measurement with humidified condition. In appearance of proton conductivity in chitin, it is considered that one more important factor is exist of amino acetyl group. Effects of amino acetyl group have been revealed by comparing to proton conductivity in chitosan which is basic structure of chitin. Considering proton conduction system of chemical polymer Nafion® which is used the most for fuel cell, it is deduced that the amino and acetyl group in chitin involves forming hydration supporting proton transport. Although, it is found that power density and proton conductivity in

Therefore, in order to improve proton conductivity, there is room for further investigation of the relationship between the appearance of proton conductivity in chitin and water molecules. These understandings are expected to present the necessary and important factors for applying polysaccharides with little change in

Chitin films were prepared with the purified chitin of under 5% of deacetylation

degree, obtained from crab (Sugino Machine Limited). This purified 2%(w/v) chitin slurry was well dispersed in distilled water and the chitin sheets were prepared by suction filtration using Teflon membrane filter (ADVANTEC, Co.) [8–10]. **Figure 2** shows the photograph of the chitin film. The thickness of the film is

The chitin fiber specimens were prepared by purifying chitin obtained from the tendon of crab's legs. Based on the article of Prosky *et al.*, the purification

costs than chemical processes.

**Figure 1.**

*fuel cell (right).*

chitin are lower than the Nafion®.

**2. Experimental**

**2.1 Sample preparation**

approximately 0.07 mm.

basic structure to electrolyte membranes.

**166**

**Figure 2.** *Photograph of chitin sheet [11].*

method was performed using a group of enzymes including α-amylase and protease obtained from *Streptomyces griseus* (Wako Pure Chemical Industries, Ltd.) [8–10]. The oriented chitosan was prepared by oriented chitin to deacetylation treatment with 25%(w/v) sodium hydroxide under reflux conditions for 5 hours.
