**3. Evaluation of fuel properties for WaFO and WaFO biodiesel**

For the purpose of Characterization of fatty acids, the WaFO was processed into test sample as per the standard preparation technique [31], while, the WaFO biodiesel was tested directly, in a Gas chromatography-Mass Spectrometer (GC–MS); and was studied from their spectral data. Accordingly, WaFO reported oleic acid, palmitic acid, stearic acid as its dominant FAs; with their concentration as 35.41%, 24.24% and 16.15%, respectively. In the same way, WaFO biodiesel reported the ethyl esters of characterized dominant FAs, with their concentration as 35.63%, 27.73% and 18.34%, respectively. Summing up, WaFO Biodiesel was made up of 51.4% of saturated FAEs and 49.18% of unsaturated FAEs; and suggested that the resultant biodiesel was evenly balanced with both saturated and unsaturated FAEs, which reflected in its molecular formula (C19H37O2).

Following that, the WaFO biodiesel was assessed for its fuel compatibility with neat diesel, and suitability in CI engines by evaluating its fuel properties in accordance with ASTM D6751 standards. To begin with, Density of WaFO biodiesel was measured using a simple hydrometer, as specified in ASTM D1298 method; and was reported to be 4.14% higher than neat diesel. Next up, ASTM D445 method was followed to measure the kinematic viscosity of WaFO biodiesel using a calibrated glass-viscosity tube, and was found to be 27.96% higher than neat diesel. Again, flash and fire point


#### **Table 1.**

*Fuel properties of WaFO biodiesel evaluated as per ASTM standards along with neat diesel and their permissible range.*

*Molecular Contribution of Fatty Acid Esters in Biodiesel Fueled CI Engines DOI: http://dx.doi.org/10.5772/intechopen.102956*

of WaFO biodiesel were reported to be 80 and 81OC higher than neat diesel, respectively; and were tested in Pensky Martens closed-cup apparatus as described in ASTM D93–16 method. And, cetane number of WaFO biodiesel, evaluated according to ASTM D613 method, was found to be 27.74% greater than neat diesel. Here, higher density, kinematic viscosity, flash point and cetane number for WaFO biodiesel than neat diesel were contributed by the long carbon chained FAEs like ethyl oleate, ethyl palmitate and ethyl stearate; yet, remained significantly lower due to the presence of unsaturated ethyl oleate in it [21, 25, 30, 32].

In contrast, calorific value of WaFO biodiesel was reported 11.1% lesser than neat diesel, upon tested inside a bomb calorimeter as per ASTM D240 method; and this reduction was clarified by its fuel bound oxygen molecules and absence of sulfur content, which fails to contribute a significant share towards its calorific value [33]. Looking into its chemical properties, saponification value and iodine vale of WaFO biodiesel was found to be 191.38 mg KOH/gm and 53.26 g I2/100 gm, on account of its increased concentration of unsaturated FAEs. Meanwhile, the acid value of WaFO biodiesel was estimated as 0.11% by using ASTM D664 method, which acknowledged the effective conversion of FFAs and monoglycerides into fatty acid esters. Lastly, analytical data related to chemical composition of WaFO biodiesel stated its average molecular weight to be 35% higher than neat diesel; whose carbon and hydrogen content was estimated to be 9.92 and 12.06% lesser than the latter fuel. Moreover, WaFO biodiesel exhibited 10.75% of oxygen content available in it; and is regarded as an oxygenated biofuel in view of this fuel bound oxygen content. **Table 1** summarizes the fuel properties of WaFO biodiesel and neat diesel evaluated as per ASTM standards, along with their permissible range and testing methods.
