Abstract
The ever-increasing population growth and economic developments have heightened demand for energy. This has resulted in depletion and ever-rising prices of petroleum diesel, thus increasing environmental degradation. These complications have motivated this study for the search of an alternative eco-friendly and renewable source of energy such as biodiesel. Biodiesel has been found to be a potential alternative fuel for diesel. Biodiesel was produced by transesterification reaction of Schinziophyton rautanenii (mongongo) nut oil in the presence of a base heterogeneous catalyst: CaO derived from eggshell ash and synthesised CaO-nanoparticles (CaO-NPs). The catalysts were calcined at a temperature of 800°C for 3 h and characterized by scanning electron microscope-energy dispersive X-ray (SEM-EDX) where both catalysts showed agglomerated particles and high elemental composition of Ca and O. Powder X-ray diffraction (XRD) showed that CaO was present in both catalysts, and the average crystalline size obtained was 42 and 50 nm for CaO-NPs and eggshell ash, respectively. Fourier transmission infrared (FTIR) spectrometer showed absorption bands of CaO in both catalysts which were at 875 and 713.46 cm−1 for CaO-NPs and eggshell ash, respectively. The analysis of mongongo nut oil (MNO) and mongongo methyl esters (MMEs) was done according to the European biodiesel specification (EN 1421) and American Society for Testing and Materials (ASTM D675). Statistically, there was no significant difference between CaO-NPs and eggshell in terms of optimum yield ( P > 0.05 ) using a sample t-test. However, in terms of catalyst loading, the eggshell was a better catalyst as it required a low catalyst load to obtain an optimum yield of 83% at 6 wt.% compared to CaO-NPs with an optimum yield of 85% at 12 wt.%. The reactions were all performed at constant reaction conditions of 9 : 1 methanol to oil ratio, 3 h reaction time, and 65°C reaction temperature.
Highlights
Ever since the revolution of industrialization, energy instability has been a challenging problem [1]
CaCO3 proving that the eggshell ash produced pure calcium oxide (CaO). e results could imply that the eggshell ash obtained was completely crystallized because of the removal of CO2 during the thermal treatment process. e successful transformation of CaCO3 to CaO is seen in the power X-ray diffraction (XRD) pattern in Figure 3 of the chicken eggshell ash-derived CaO calcined at 800°C and eggshell, and the results are similar to those reported by Hua et al [34]. e estimated average particle size of the chicken eggshell ash-derived CaO was calculated to be 50 nm
calcium oxide nanoparticles (CaO-NPs) sample calcined at 800°C matched with COD 9006694 was chosen to be used in the production of biodiesel from mongongo nut oil because it had more of CaO and it was expected that it would give a better yield compared to the sample calcined at 900°C
Summary
Ever since the revolution of industrialization, energy instability has been a challenging problem [1]. Scientists have been working hard in search of finding reliable, secure, clean, affordable, and sustainable energy resources [2]. Energy resources can be categorized into 3 major groups: fossil fuels, renewable, and fissile [3]. Biodiesel is one of the promising alternative sources of energy because it is a renewable source of energy. Fissile fuels are nuclear energy forms [4]. Fissile sources of energy include uranium and thorium. Renewable energy sources include biomass, hydro, wind, solar, marine, and hydrogen [5]. Fossil fuels are nonrenewable source of energy, and they have a negative impact on the climate through global warming [6]. Biodiesel has attracted much needed attention as an alternative source of energy because of its easier accessibility [8].
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