## 3 Results
### Structural Characteristics of the Bio-membrane with Thermal Treatment  
The several treatments of the bio-membrane were analyzed by Fourier-transform infrared spectroscopy (FTIR) in order to identify its functional groups contained. Characteristic peaks of N-H at 719 cm\({}^{-1}\), C=O at 1,728 cm\({}^{-1}\), C-O at 1,463 cm\({}^{-1}\), C=C at 1,641 cm\({}^{-1}\), C-H at 2,849 and 2,917 cm\({}^{-1}\) and O-H at 3,285 cm\({}^{-1}\) were observed (Figure 3).  
As shown in Figure 3, the FTIR profile of the bio-membranes is similar, which indicates that the chemical structure is maintained despite the thermal treatment undergone by the propose bio-membrane, and further, this membrane compared to the others that support a solvent (clean up and immersion), or a mechanical stress undergoes a modification minor at bands. The clean-up treatment with solvents (Chloroform, ethyl ether, Hexane, methanol) shows that the OH band decreases, indicating a dehydration. The functional groups found are consistent with the extracellular lipid membrane, composed by amorphous polyester (-CO-NH-) which is formed from the condensation of hydroxy-acids of 16 and 18 carbon atoms [23]. The thermal treatment applied to the bio-membrane generates a stable film useful to separate the anode from the cathode, preventing a short circuit.  
Morphology is another important aspect to evaluate in membranes because their channels or clusters have a positive impact upon their ionic conductivity by allowing mass transport (mainly ion conductivity and water transport) [39].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **E (volts)** & **i (mA)** & **Conductivity mS cm\({}^{-2}\)** \\ \hline
**Hydrogen fuel cell with Nafion membrane** & 0.81 \(\pm\) 0.01 & 1.00 \(\pm\) 0.05 & 4.29 \\
**Hydrogen fuel cell with thermal bio-membrane** & 0.70 \(\pm\) 0.03 & 0.09 \(\pm\) 0.01 & 1.06 \\
**Methanol fuel cell with Nafion membrane** & 0.46 \(\pm\) 0.02 & 0.30 \(\pm\) 0.02 & 1.11 \\
**Methanol fuel cell with thermal bio-membrane** & 0.50 \(\pm\) 0.01 & 0.50 \(\pm\) 0.02 & 7.14 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Electric data of the bio-membrane performance in a methanol fuel cell and hydrogen fuel cell at room temperature (298 K).  
Bio-membrane morphology was studied through scanning electron microscopy (SEM). The surface stomata of the non-treated _Agave salmiana_ bio-membrane (Figure 4a) are observed to be closed, limiting ion transfer and reducing its life time in an electrochemical system. The surface of the thermally-activated membrane (Figure 4b) displays stimulated stomata, which is desirable for ion (proton) transfer. From these observations, it is also possible to deduce an increased contact area and decreased electrical resistance.  
Figure 3: Fourier-transform infrared spectroscopy (FTIR) spectrum of the several treatments of the bio-membrane: Without Treatment, Immersion (H\({}_{2}\)O, H\({}_{2}\)SO\({}_{4}\), NaOH), Clean-up (Chloroform, ethyl ether, Hexane, methanol), Polymeric Coating (Nafion), Scraping and Thermal.  
One way of corroborating that there is a conductive improvement (efficiency) in a modified bio-membrane is to record an impedance spectrum using four electrodes at 0.2 V. Figure 5 shows a decrease in the electrical resistance of the thermally-treated bio-membrane, which indicates an increase in ionic conductivity, and therefore in its efficiency, which makes it an option as a bio-membrane in an electrolyzer or fuel cell [21,22].