**2. Traditional methods used in biodiesel characterization**

One way is the use of resources produced by agribusiness [3]. This transition to sustainability was mainly determining the need or strategic interest to replace oil with other materials. Vegetable oils as alternative fuels have begun being studied in the late nineteenth by Rudolph Diesel, inventor of the internal combustion engine century, and these were used in natura. But the direct use in engines came up with many problems, for example, oily material accumulation in the injection nozzles, the incomplete oil burnt, coal deposit formation in the combustion chamber, low power efficiency and, as a result of firing, the release of acrolein (propenal) which is toxic. Studies of alternatives have been considered for best performance of vegetable oils in diesel engines, for example, dilution, micro-emulsion with methanol and ethanol, catalytic cracking and trans-esterification reaction with short alcohols chains. Among these alternatives, the trans esterification reaction has been the most used, since the process is relatively simple and the product (biodiesel) has properties similar to those of petro diesel, such as viscosity

Biodiesel can be produced from a variety of materials. These raw materials include most vegetable oils (soybean oil, cottonseed, palm, peanut, rapeseed/canola, sunflower, safflower, coconut oil) and animal fats (tallow) and discard oil (frying oils). The raw material choice for biodiesel production depends largely on geographical factors. Depending on the origin and

One of the great advantages of using biodiesel as fuel is linked to the environmental benefits; it has some features that represent advantages over petroleum-based fuels, such as absence of aromatics and sulfur; high cetane amount; average oxygen content; higher flash point; lower pollutants emission and good lubricity. Another advantage of biodiesel is the substitution of

The petroleum oils are stable at distillation temperature, even in the presence of excess oxygen. Unlike vegetable oils containing unsaturated compounds, the oxidation reaction can be observed up to room temperature and the temperature close to 250 °C because of the additional thermal decomposition reactions, leading to the formation of polymeric compounds by

Toward such facts, the current context of scientific and technological development aimed at the emergence of new technologies and feasibility of application throughout the shortest time, as well as innovations that allow the search for global goal of transition to a sustainable economy. For this purpose, a possible alternative would be to replace the fossil diesel for biodiesel production or diesel/biodiesel mixture, which allows increasing the volumes of the mixtures reservations, what is highly interesting toward biodiesel production from a variety of renewable raw materials. Regarding to such purpose the use of analysis tools physico‐ chemical behavior of biodiesel or biodiesel blends containing, enabling the acquisition of information and the establishment of values that ensure the optimal operation of engines, are desirable. Therefore, the use of thermal analysis techniques, such as Thermogravimetry/ Derivative Thermogravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC) has produced excellent results, contributing to a historical development of scientific applications. Thermal analysis is an important tool for the determination of thermodynamic properties, heat capacity, phase transition temperatures, among other perfectly applicable for determining the

quality of the raw material, changes in the production process may be required [5].

those in diesel engines without the need for any modifications to the engine [6].

and density [4].

252 Biofuels - Status and Perspective

condensation reaction [7].

The quality biodiesel must be produced following strict industry specifications, according to ASTM D6751 international level. In Brazil, the National Agency of Petroleum, Natural Gas and Biofuels (ANP) by ANP Resolution Nº 45, dated 08.25.2014 specifies the characteristics of the product. According to the resolution Physicochemical characteristics of biodiesel must be made through the use of the guidelines of the Brazilian Association of Technical Standards (ABNT) standards "American Society for Testing and Materials" (ASTM), "International Organization for Standardization" (ISO) and the "Comité Européen de Normalisation" (CEN). Some of the characteristics of the specification of biodiesel can be seen in Table 1.

In Brazil, through an aggressive government policy, thousands of Biodiesel production industries have been installed in all regions of the country, and this material is already mixed with diesel consumed at the pump stations. This fact makes the ANP hold a national moni‐ toring program of the fuel sold in the country, with the association of accredited laboratories for this purpose. Testing methodologies validated by ASTM protocols are employed routinely evaluating samples collected in various parts of the country supply.

Biodiesel, when subjected to low temperatures is likely to present problems in the performance of fuel systems of cars. In winter, the crystallization of the methyl esters of saturated fatty acids can cause clogging of filters and pipes [8]. The cold flow properties of diesel are usually characterized by three temperature measurements following: Point cloud point (CP) connect‐ ing the cold (CFPP) filter and pour point (PP). Initially, the cooling temperatures causes the formation of seed crystals of wax which are solid at submicron invisible to the human eye level. Further decreases in temperature cause the nuclei to grow crystal [9]. Temperature at which crystals become visible is defined as the cloud point (CP), since the crystals form a generally hazy and cloudy suspension. The temperature at which the agglomeration of the crystal is large enough to prevent leakage of fluid free is defined as the pour point (PP). The filter plugging point at low temperature (CFPP) is then defined as the lowest temperature at which 40 mL of oil passes through the filter securely within 60 s. Crystallization of these compounds may lead to filters and pipes connected.

Previous studies concerning the cold flow properties of biodiesel have determined that the lengths of the hydrocarbon chains and the presence of unsaturated structures significantly affect its low-temperature properties [10-12].

In addition to these cold temperature tests, DSC should also be used to monitor the crystalli‐ zation of multicomponent mixtures like biodiesel because CP results represent only the beginning of the crystallization process, and PP and CFPP cover the beginning of the operative problems; but none of these tests monitor the full range of crystallization. DSC is a wellestablished method for determining latent heat changes in a material upon either cooling (exothermic crystallization peaks) or heating (endothermic melting peaks). This method has been applied to monitor biodiesel crystallization and is generally considered to be more repeatable and more accurate than classical methods, such as PP or CP measurements, commonly used in industrial settings [13].

### **3. Biodiesel**

Biodiesel is defined as alkyl esters (methyl, ethyl, propyl), commonly obtained from a chemical reaction of a vegetable oil or animal fat [14-17] with an alcohol (usually methanol) in the presence of a catalyst (usually sodium hydroxide or potassium hydroxide) in a call type for the trans-esterification [18-19] (Figure 1). This reaction produces glycerin as a byproduct, which ought to be widely applied in the chemical industry [5].This glycerin vegetable oil removed leaving the less viscous oil [20]. With its break, glycerin joins caustic soda (sodium hydroxide or potassium hydroxide) [21]. The remainder of the molecule (fatty acid) binds to the alcohol, forming biodiesel. Besides the glycerin, the biodiesel production chain generates a number of other co-products (pie, bran etc.) that can add value and constitute other important sources of income for farmers. Biodiesel is formed by different types of fatty acid esters, particularly the acids: oleic, linoleic and palmitic acids [22-25]; that can also be obtained by esterification and cracking process [26].

**Figure 1.** Transesterification Reaction

### **3.1. Biodiesel production**

40 mL of oil passes through the filter securely within 60 s. Crystallization of these compounds

Previous studies concerning the cold flow properties of biodiesel have determined that the lengths of the hydrocarbon chains and the presence of unsaturated structures significantly

In addition to these cold temperature tests, DSC should also be used to monitor the crystalli‐ zation of multicomponent mixtures like biodiesel because CP results represent only the beginning of the crystallization process, and PP and CFPP cover the beginning of the operative problems; but none of these tests monitor the full range of crystallization. DSC is a wellestablished method for determining latent heat changes in a material upon either cooling (exothermic crystallization peaks) or heating (endothermic melting peaks). This method has been applied to monitor biodiesel crystallization and is generally considered to be more repeatable and more accurate than classical methods, such as PP or CP measurements,

Biodiesel is defined as alkyl esters (methyl, ethyl, propyl), commonly obtained from a chemical reaction of a vegetable oil or animal fat [14-17] with an alcohol (usually methanol) in the presence of a catalyst (usually sodium hydroxide or potassium hydroxide) in a call type for the trans-esterification [18-19] (Figure 1). This reaction produces glycerin as a byproduct, which ought to be widely applied in the chemical industry [5].This glycerin vegetable oil removed leaving the less viscous oil [20]. With its break, glycerin joins caustic soda (sodium hydroxide or potassium hydroxide) [21]. The remainder of the molecule (fatty acid) binds to the alcohol, forming biodiesel. Besides the glycerin, the biodiesel production chain generates a number of other co-products (pie, bran etc.) that can add value and constitute other important sources of income for farmers. Biodiesel is formed by different types of fatty acid esters, particularly the acids: oleic, linoleic and palmitic acids [22-25]; that can also be obtained by

OH

OH

+ <sup>3</sup> <sup>R</sup>

O

O CH3

OH

may lead to filters and pipes connected.

254 Biofuels - Status and Perspective

affect its low-temperature properties [10-12].

commonly used in industrial settings [13].

esterification and cracking process [26].

**3. Biodiesel**

O

R1

O

O

R3

O

O

O

**Figure 1.** Transesterification Reaction

R2

+ 3CH OH

The transesterification reaction ought to be carried out in a reactor glass, jacketed for temper‐ ature control by circulating water, and mechanical agitation. The system temperature main‐ tained around 50 °C. By adding 230 mL of anhydrous methanol and about 8.2 g of catalyst (NaOH), then completed dissolution of the catalyst by adding to 900 mL of soybean oil, establishing this moment as time zero of the reaction. The reaction time lasted about 45 min, in the first minutes were observed the conversion of esters by the sudden darkening of the mixture. Once the reaction is complete, the reactional mean is transferred a separator funnel and the formation of an upper layer corresponding to the methyl esters, a bottom phase containing glycerol formed from the reaction and add to excess methanol hydroxide sodium which does not react. Gathered to the reaction were formed soaps, and some traces of methyl esters and partial glycerides. Then the separated the two phases by decantation.

After the phases' separation, the obtained esters must be purified by washing them with a solution containing distilled water at 90 °C and 0,5 % concentrated HCl in order to neutralize the remaining catalyst of the reaction. The total neutralization is confirmed by adding phenolphthalein indicator 1 % (w/v), to the washing water. The aqueous phase, separated by decantation, followed ester and traces of moisture removed by subsequent filtration over anhydrous sodium sulfate. For the recovery of the excess methanol added in, there shall be the glycerin residue distillation at 80 °C under moderate vacuum [6].

### **3.2. Biodiesel physical-chemical characterization**

Physicochemical parameters of biodiesel samples (methyl route) obtained by following the rules set by the Technical Regulation of ANP contained in Resolution Nº45/2014 of the National Agency of Petroleum, Natural Gas and Biofuels-ANP. Three samples of soybean biodiesel were analyzed, one that was produced in the laboratory (BL) and two industrial, one trans esterified with used oil (BI-01) and another with new oil (BI-02). All traits and methods used are in table 1.

Biodiesel developed in the laboratory (BL) has filed all within the parameters established by the Resolution of the ANP, except oxidation stability. Biodiesel oxidation occurs because the oils used as its raw materials containing unsaturated compounds, which are subject to oxidation reactions that take place at ambient temperature. Oxidation products cause corrosion in engine parts and deposit formation causing obstruction in the filters and injection system [5]. Therefore, the less subject to oxidation, the better the quality of biodiesel during its useful cycle. However, the value obtained for the oxidation stability out of specification is significant not to cause corrosion in the short term, long term only [5]. This parameter out of specification can be explained by the fact that after the transesterification process has not any added antioxidant (slow oxidative process biodiesel) unlike the industrial biodiesels.

The industrial biodiesel 01 (BI-01) showed three parameters that are out of specification the ester content, carbon residue, and total glycerol. The raw material used by the industry in producing biodiesel is the soybean oil used according to [5], oils used contain water, typically


\*CIA – clear and impurities absent

\*\*Out range parameters

**Table 1.** Biodiesel Samples Physical-chemistry Characteristics

from 2 to 7% FFA, Free Fat Acid, when an alkali catalyst (e.g. KOH) is added to these raw materials FFA react with the catalyst to form soap and water. The soaps formed during the reaction are removed with the glycerol in the aqueous washing step. When the concentration of FFA is too large soaps inhibit the phase separation between methyl ester and glycerol and contribute to emulsion formation during the aqueous rinse. With all this explains why the ester content, carbon residue and total glycerol present parameters out of specification. It is likely that the raw material should not have had a proper treatment for the transesterification reaction having a high content of FFA, with that, there was a decrease in the yield of the reaction, which may have been the reason for the ester content display a value specified below and the content of total glycerol be above specified. This above total content of glycerol may explain the residue carbon, as these fuels with high amounts of free glycerol present problems with deposition in storage tanks glycerol creating a viscous mixture that can clog fuel filters and in the case being responsible for above the value specified for the carbon residue. To be able to prove it would be necessary to make analysis with the raw material.

The industrial biodiesel 02 (BI-02) showed only the acid out of the specified. In this case biodiesel, one possible explanation microbial growth in the fuel owing to the presence of water in its shell. The presence of microbes cause increased acidity and formation of sludge that can clog fuel filters. Another cause of high acidity could be related to the process of preparation of biodiesel, because if it is not washed with acid and the withdrawal is made correctly, the product may present acidity nonstandard.
