Fuel characterisation results for cottonseed biodiesel-chicken biodiesel blends

Around 2.2 kg of oil was rendered from 5kg waste chicken skin; hence rendering yield was 43.5%. On the other hand, biodiesel yields of both transesterifications of the chicken and cottonseed oil were approximately 92%.

Table 5.2 illustrates the mass percentages of saturated FAMEs for CO100 and CH100 as 26.7% and 28.8%, respectively. Similarly, overall unsaturated FAMEs were also close to each other as 73.3% and 71.2%. However, a significant difference was observed on the type of unsaturated FAME i.e. monounsaturated and polyunsaturated. This was an important detail as the type of unsaturated FAME play a crucial role in fuel properties (Masera and Hossain, 2017). According to the results, CO100 was mainly composed of C18:2 as 51.7%, whereas CH100 mainly had C16:1 and C18:1 as 48.8% in total.

Table 5.2. Fatty Acid Methyl Ester compositions of the biofuels, adapted from the author’s published paper (Masera and Hossain, 2019).

FAME Mass percentage (%)

CO100 CO80CH20 CO60CH40 CO50CH50 CO30CH70 CO10CH90 CH100

C14:0 0.7 0.6 0.6 0.6 0.6 0.6 0.6 C16:0 23.2 21.8 21.7 21.5 21.6 21.5 21.7 C16:1 0.5 1.4 2.1 3.1 4 5.1 5.4 C18:0 2.8 3.8 5.2 5 5.7 6.2 6.6 C18:1 20.9 25.8 30.9 32.6 36.8 40.9 43 C18:2 51.7 46.5 39.4 37.3 31.3 25.4 22.4 C18:3 0.2 0.2 0 0 0 0.3 0.4 C20:0 0.1 0 0 0 0 0 0 Total saturated 26.7 26.2 27.6 27.1 27.9 28.3 28.8 Monounsaturated 21.6 27.3 33 35.7 40.8 46.3 48.8 Polyunsaturated 51.7 46.5 39.4 37.3 31.3 25.4 22.4

Figure 5.3 demonstrates the TLC chromatography results of the cottonseed oil, chicken fat and their biodiesel versions. According to Figure 5.3, TAGs were the most dominant compound in the oils. Figure 5.4 also showed that TAGs were main source of the feedstock that was converted into biodiesel. Note that FFA, DAG and MAG compounds could not be quantified as their concentrations were below the detection point.

(a) (b)

(a)

(b)

Figure 5.4: GC-ms results of the (a) chicken fat TAG and (b) chicken biodoesel FAME. Chicken biodiesel CH100 mainly composed of C16:0, C18:1 and C18:2. (C17:0 was added as an internal standard).

Fuel properties of the test biodiesels and diesel are shown in Table 5.3. Moreover, BS EN 14214 biodiesel standard (British Standard Institution, 2010) and EN 590 diesel standard (European Standard EN 590:2013, 2009) are also included as reference. The biggest differences of the neat biodiesels were on cetane number, viscosity, degree of unsaturation and iodine value. Therefore, they were the major parameters affected from cottonseed-chicken biodiesel blending. Influence of blend ratio on cetane number and viscosity was given in Figure 5.5. Both cetane number and viscosity were increased as the chicken biodiesel fraction of blends increased. This can be attributed to the relatively low amount of polyunsaturated FAME content of the CH100 as 22.4% (Masera and Hossain, 2019).

Table 5.3. Fuel properties of the test fuels with the corresponding EN14214 biodiesel (British Standard Institution, 2010) and EN 590 diesel (European Standard EN 590:2013, 2009) standard, adapted from the author’s published paper (Masera and Hossain, 2019).

Fuel Units Biofuels BS EN 14214 EN 590

Properties CO100 CO80CH20 CO60CH40 CO50CH50 CO30CH70 CO10CH90 CH100 Diesel Biodiesel Diesel

Standard Standard

Viscosity at 40°C (mm2_{/s) 4.33 4.48 4.66 4.92 5.10 5.16 5.36 2.78 3.5 - 5.0 2.0 - 4.5} Density (g/cm3_{) 0.884 0.882 0.882 0.881 0.880 0.880 0.878 0.828 0.86 - 0.90 0.820 - 0.845}

Flash Point (°C) 176 176 173 171 168 165 165 61.5 min 101 min 55

Cetane numbera _{() 54 55 57 57 59 60 60 53.5 min 51 min 51}

Cetane numberb _{() 52 52 54 54 56 56 57 53.5 min 51 min 51}

Carbon, theoretical (%) 76.69 76.77 76.85 76.84 76.79 76.49 76.44 n/a n/a n/a Carbon, measured (%) 77.58 n/a 74.69 74.20 76.12 n/a 75.67 86.6c _{n/a n/a} Hydrogen, theoretical (%) 11.93 11.98 12.05 12.06 12.09 12.09 12.10 n/a n/a n/a Hydrogen, measured (%) 12.33 n/a 12.49 12.41 11.33 n/a 11.96 13.4c _{n/a n/a} Oxygen, theoretical (%) 11.08 11.08 11.10 11.11 11.11 11.08 11.08 n/a n/a n/a Oxygen, measured (%) 10.09 n/a 12.82 13.40 12.55 n/a 12.38 0.07c _{n/a n/a}

HHV (MJ/kg) 39.4 39.4 39.6 39.4 39.1 39.6 39.3 45.2 n/a n/a

LHV (MJ/kg) 37 37 37 37 37 37 37 42 n/a n/a

Iodine number (g/100g) 108 104 97 95 90 84 81 n/a max 120 n/a

Linolenic acid methyl ester (%mol/mol) 0.2 0.2 0 0 0 0.3 0.4 n/a max 12 n/a

Monoglyceride (MAG) (%mol/mol) ND ND ND ND ND ND ND ND max 0.8 n/a

Diglyceride (DAG) (%mol/mol) ND ND ND ND ND ND ND ND max 0.2 n/a

Triglyceride (TAG) (%mol/mol) ND ND ND ND ND ND ND ND max 0.2 n/a

Methanol (%mol/mol) 0 0 0 0 0 0 0 n/a max 0.2 n/a

Acid value (mg KOH/g) 0.228 0.200 0.200 0.171 0.172 0.172 0.172 0.091 max 0.5 n/a Degree of Unsaturation (Weight %) 125 120 112 110 103 97 94 n/a n/a n/a a= (Ramírez-Verduzco et al., 2012); b= (Tong et al., 2011); c= (Schönborn et al., 2009); ND= Not detected

Figure 5.5. Variation of viscosity and cetane number with respect to cottonseed-chicken biodiesel ratio, adapted from the author’s published paper (Masera and Hossain, 2019).

Literature pointed viscosity as one of the most important fuel property due to its direct effect on fuel combustion (Alptekin and Canakci, 2009). Viscosity of chicken biodiesel was not complied with the BS EN 14214 standard as it was measured as 5.36 mm2_{/s at 40⁰C. This can be linked to relatively low} iodine value of the chicken biodiesel which was 81 g/100g. The literature also stated higher viscosities for low iodine value FAMEs (Schönborn et al., 2009). However, viscosity was improved when cottonseed biodiesel was added into chicken biodiesel and blends with minimum 50% cottonseed biodiesel met the BS EN 14214 standard in terms of viscosity Figure 5.5. Density is another fuel property directly effects engine performance and combustion (Emiroğlu et al., 2018). All biodiesels found suitable with the BS EN 14214 standard in terms of density. The highest density was measured for CO100 as 0.884 g/cm3_{. Densities of blends were increased by the cottonseed biodiesel blending.} Flash point is an important parameter for safe storage and transport of the fuels (Masera and Hossain, 2019). The flash points of all biodiesels complied with the standard and measured between 176°C and 165°C. Cetane number is a good measure of the ignition quality of any fuel (Kurtz and Polonowski, 2017). All biodiesels met the BS EN 14214 standard in terms of cetane number as they were above the minimum limit of 51. However, the highest CN measured for chicken biodesel as 60 was reduced with the cottonseed biodiesel blending. This was the biggest drawback of cottonseed biodiesel blending of chicken biodiesel. Nevertheless, this scarify from cetane number can be acceptable as the CN of optimised biomixtures such as CO60CH40 and CO50CH50 were 57 and higher than diesel having CN of 53.5. The carbon, hydrogen and oxygen contents of the test biodiesels similar to each other and good agreement with the literature (Giakoumis, 2013). The HHV and LHV of biodiesels were very similar to each other as 39.4 MJ/kg and 37 MJ/kg; these values were slightly lower than diesel Table 5.3. As mentioned earlier, DU and IV are both measuring the same fuel property which is saturation

level (Schober and Mittelbach, 2007). All biodiesels complied with the BS EN14214 iodine value standard declared as maximum 120 g iodine/100g. IV of blends increased with the increased cottonseed biodiesel fraction. Acid value of a biodiesel shows its resistance to ageing (Predojević, 2008). Acid values were all measured within the range declared by the BS EN 14214. This was a good indication of biodiesels safe usage in CI engines in terms of corrosion and pump plugging and (Predojević, 2008; Emiroğlu et al., 2018). Ultimately, the high viscosity of CH100 was successfully reduced and 5.00 mm2_{/s viscosity requirement of BS EN 14214 standard was met by cottonseed} biodiesel blending. For example, CO60CH40 and CO50CH50 were high quality biomixtures which also complied with the standard.

Fuel characterisation of the biomixtures i.e. CO50CH50 were in good agreement with the similar studies in the literature. For example, Benjumea et al., (2011) studied palm/linseed biodiesel blends at 50/50 volume fraction. The blend had similar HHV as 39.8 MJ/kg, density as 0.885 g/cm3 _{and iodine} value as 112.7 g/100g with the CO50CH50. However, the blend had 10% lower CN as 51.3 than CO50CH50 biomixture. In another study, Sanjid et al. (2016) studied the kapok biodiesel-Moringa biodiesel-diesel blend with volume ratio of 10/10/80 respectively. The biofuel had around 30% lower viscosity value than CO50CH50, this can be attributed to the high percentage of diesel as 80%. However, CN of the biofuel was around 16% lower than CO50CH50. To sum up, the biomixtures produced and analysed in this chapter had comparable fuel characteristics with similar types of biofuel blends in the literature. Furthermore, the biomixtures produced in this research like CO60CH40 and CO50CH50 had superior cetane numbers over the literature due to relatively high CN of chicken biodiesel as 60.