**5. TG profile of biodiesel samples**

**Figure 2.** TGA curve (dark-red) and its derivative, DTG (blue)

**4.2. Differential Scanning Calorimetry (DSC)**

sample and reference at the same temperature.

regardless the thermal event that is occurring in the sample.

former is called a power compensation DSC and second DSC heat flow.

temperature or time.

258 Biofuels - Status and Perspective

change in heat capacity [28].

Differential Scanning Calorimetry (DSC) is defined as a technique which measures the temperatures and energy change associated with transitions in materials as a function of

DSC measures the difference in energy required for the substance and a reference material, thermally inert, while both are subjected to a controlled temperature variation so that the sample and reference are maintained under isothermal conditions, in relation the other,

The DSC curve provides qualitative and quantitative information about physical and chemical changes that involve endothermic processes (heat absorption), exothermic (releasing heat) or

There are two types of equipment that perform the Differential Scanning Calorimetry, the

In power compensation DSC for the sample and the reference are placed in separate compart‐ ments of individual heat sources where the temperature and energy are monitored and generated by filaments of the same platinum, acting as resistive heaters and thermometers. This technique keeps constant the supplied heat. However, instead of measuring the difference in temperature between sample and reference during the reaction, a control system immedi‐ ately increases the power supplied to the sample when the process is endothermic and increases the energy supplied to the process when reference is exothermic, thus preserving the

The TG curves were obtained in TGA equipment-Q50 from TA Instruments in an atmosphere of nitrogen at a flow rate of 100 mL min-1, heating rate 20 °C min-1 in crucibles of platinum (Pt) as a support, in temperature range 30-650 °C.

In the TG curves of the methyl esters was only one event, which consumed more than 99 % of the sample mass. This step of weight loss is associated to vaporization of the methyl esters and the TG curve show the process end around 300 °C. Figure 4 and 5, show the comparison of the profile of the TG and DTG curves of the three samples, where it ought to be observed the similarity between them.

**Figure 4.** TG Profile of Biodiesel Samples

These curves showed very similar profile among them, the BI 02 showed a slightly higher thermal stability than the BI and BL-01, this fact can be related to oxidative stability, BI-02 showed higher oxidative stability than the other samples. The profile of the TG curves of the samples of biodiesel was similar to the soybean oil and fossil diesel, with only one step weight loss. The difference is in the temperature range in which vaporization of the methyl ester, soybean oil and fossil diesel occurs, begin around 155 °C, 357 °C and 30 °C respectively, as shown in Figure 6.

The large difference in thermal stability between the soybean oil and biodiesel is due to the fact that the oil molecules are larger than the samples of biodiesel oil is composed primarily of triacylglycerols while the biodiesel is composed of the methyl esters of fatty. Despite Soybean Oil satisfactory performance as a fuel or as a fuel source its spread is compromised, because its cost is high when compared to petroleum. Apart from being highly viscous, causing poor fuel atomization in the combustion chamber of the engine, causing serious operational problems such as the occurrence of deposits in their inner parts [5].

The biodiesel commercialization is made by mixtures with fossil diesel, the energy matrix was introduced in 2005 with the addition of 2 % of this fuel and currently the law determines to be

**Figure 5.** DTG Profile of Biodiesel samples

the TG curve show the process end around 300 °C. Figure 4 and 5, show the comparison of the profile of the TG and DTG curves of the three samples, where it ought to be observed the

These curves showed very similar profile among them, the BI 02 showed a slightly higher thermal stability than the BI and BL-01, this fact can be related to oxidative stability, BI-02 showed higher oxidative stability than the other samples. The profile of the TG curves of the samples of biodiesel was similar to the soybean oil and fossil diesel, with only one step weight loss. The difference is in the temperature range in which vaporization of the methyl ester, soybean oil and fossil diesel occurs, begin around 155 °C, 357 °C and 30 °C respectively, as

The large difference in thermal stability between the soybean oil and biodiesel is due to the fact that the oil molecules are larger than the samples of biodiesel oil is composed primarily of triacylglycerols while the biodiesel is composed of the methyl esters of fatty. Despite Soybean Oil satisfactory performance as a fuel or as a fuel source its spread is compromised, because its cost is high when compared to petroleum. Apart from being highly viscous, causing poor fuel atomization in the combustion chamber of the engine, causing serious operational

The biodiesel commercialization is made by mixtures with fossil diesel, the energy matrix was introduced in 2005 with the addition of 2 % of this fuel and currently the law determines to be

problems such as the occurrence of deposits in their inner parts [5].

similarity between them.

260 Biofuels - Status and Perspective

**Figure 4.** TG Profile of Biodiesel Samples

shown in Figure 6.

**Figure 6.** Soybean Oil, Biodiesel and Diesel Fossil TG Profile

plus 5 % biodiesel to fossil diesel. We observed the TG/DTG profile of the mixtures as shown in figure 7 and 8.

**Figure 7.** Profile of TG Fossil Diesel and biodiesel (BI 02) blends

**Figure 8.** Profile of DTG Fossil Diesel and Biodiesel (BI 02) blend

The TG curves of mixtures of samples added to Biodiesel Diesel Fossil showed similar profiles with only one stage of mass loss (for mixtures with BL and BI 01 curves were similar to BI 02 profile, so only presented a figure 7. The curves profile of mixtures in all ratios, was similar to that of vaporization of fossil diesel profile, it was found that an increase of the concentration of biodiesel there was a displacement of the curve to higher temperatures, indicating a higher relative stability of the mixture to pure fossil diesel.
