Recycling calcium oxide nanoparticles for sustainable biodiesel production from nonedible feedstock Argemone mexicana L.

Figures & data

Table 1. Fuel properties of Argemone mexicana biodiesel (AMB), and American society for testing and materials (ASTM) standard methods adopted.

Fuel property	ASTM method	ASTM test limit	AMB-B100%
Acid value (KOH mg/kg)	ASTM D-664	0.80	0.49
Calorific value kJ/kg	D-5865	35,000	28,582
Carbon residue	ASTM D-4530	0.05	0.03
Cetane no.	D-613	45	48
Cloud filter plug point (°C)	ASTM D-6751	–	−18
Cloud point (°C)	D-2500-11	−3 to 12	−1.2
Density at 15 °C (kg/L)	D-4052	0.820–0.900	0.8827
Distillation temperature 90% recovery	ASTM D-1160-06	360	329
Flash point (°C) Pensky-Martens closed cup (PMCC)	D-93	130	134
Higher heating value (MJ/kg)	ASTM D-240	39–43	40.07
Iodine number (mg I2/100)	ASTM D-4607	≤120	113.7
Kinematic viscosity at 40 °C (cSt)	D-445	1.9–6	5.73
Oxidative stability 110 °C (h)	EN-14112	Min. 3 h	1.78
Pour point (°C)	D-97-12	−15 to 16	−10.8
Refractive index @ 40 °C	ASTM D-1747	–	1.453
Sulphur (% wt)	D-5453	0.007	0.0016
Water content (mg/kg)	ASTM D-6304	≤0.05	0.017

Figure 1. Scanning electron micrographs of synthesised nanoparticles: (a) 0.5 µm × 5000; (b) 0.5 µm × 10,000; (c) 1 µm × 5000; (d) 1 µm × 10,000.

Figure 2. (a) XRD spectrum of CaO nanoparticles; (b) thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC); (c) FT-IR spectra of CaO nanoparticles.

Figure 3. Parametric optimisation of biodiesel yields: (a) the effect of oil-to-methanol ratio; (b) the effect of catalyst dosage; (c) the effect of reaction temperature; (d) the effect of reaction time.

Figure 4. (a) Catalytic activity of recycled CaO nanoparticles; (b) scanning electron micrograph of CaO nanoparticles after the fifth recovery.

Figure 5. Spectroscopic analysis of the synthesised biodiesel: (a) ¹H-NMR spectrum; (b) ¹³C-NMR spectrum; (c) GC-MS spectrum; (d) FT-IR spectrum.

Table 2. Reported FAMEs, retention time, and percentage.

S. n.o	Identified FAMEs	Retention time	Concentration (%) of compound
1	Caprylic acid methyl ester	4.739	1.17
2	Lauric acid methyl ester	8.077	1.33
3	Pentadecanoic acid methyl ester	11.627	1.24
4	Palmitic acid methyl ester	13.424	12.78
5	Stearic acid methyl ester	17.897	5.39
6	Oleic acid methyl ester	18.375	21.35
7	Linoleic acid methyl ester	19.659	47.82
8	Linolenic acid methyl ester	21.743	6.95
9	Erucic acid methyl ester	33.91	1.97

Table 3. Various functional groups and their peaks identified in the FT-IR spectrum of biodiesel.

S. no.	Functional group	Peak observed (cm^–1)
1	Methylene (stretching band)	2962.67
2	Methyl (stretching band)	2819.25
3	Methoxy-carbonyl (methyl ester)	1738.41
4	Methylene	1479.04
5	Tri-methyl	1436.33
6	Methyne C-H band	1342.59
7	Aromatic ether (aryl-O stretching)	1262.71
8	Alkyl-substituted ether	1151.93
9	Primary alcohol	1025.62
10	Methyne of skeletal C-C vibration	992
11	Methylene-(CH2)n- rocking	751.37

Data availability statement

All the data are given in the article.