Eze S. Biodiesel potential of Cucumeropsis mannii (white melon) seed oil: A neglected and underutilized resource in Nigeria

A major challenge in the biodiesel industry is the availability of high-quality vegetable oil feedstocks. Thus, there is a continuous search for quality biodiesel feedstock whose production will trigger economic impact on the agricultural sector, minimize land degradation and without significant disruption to the food chain. In this work, we extracted and analysed oil from neglected and underutilized Cucumeropsis mannii seeds for their potential in biodiesel production. The oil content of C. mannii seed was 40.8 ± 0.56%. GC-MS analysis of the oil revealed the presence of 47.0% saturated fatty (predominantly palmitic acid, stearic acid) and 53.0% of unsaturated fatty acids (predominantly oleic, linoleic and erucic acids). The physicochemical properties were determined and values were as follows: iodine value (111.07 ± 0.15 g/100 g), saponification value (192.03 ± 0.37 mg/kg of oil), peroxide value (2.60 ± 0.10 meq/kg), acid value (4.20 ± 0.02 mgKOH/g) free fatty acid (2.51 ± 0.02%), relative density (0.93 ± 0.02), the refractive index at 28 °C (1.46 ± 0.04) and viscosity at 30 °C (3.00 ± 0.10 mm²/s). The fuel properties namely, cloud point, pour point, flash point and caloric value were determined and the values were 3.03 ± 0.11 °C, 1.00 ± 0.10 °C, 279.04 ± 0.99 °C and 31.10 ± 0.11 MJ/kg, respectively. In addition, the protein content of the defatted seed was found to be 47.4 ± 0.61 g/100 g. The defatted protein-rich cakes can be upgraded as a food additive; thus the C. mannii seed oil can serve as biodiesel feedstock without altering the food chain. These characteristics demonstrate the potential of C. mannii oil as a high-quality feedstock for biodiesel production. We envisage that its utilization as biodiesel feedstock will improve the market value of these seeds, thus supporting the economic development of local farmers in rural areas.

Graphene-based catalysts for biodiesel production: Characteristics and performance

Biodiesel is a promising alternative to reduce the dependency on fossil fuels. However, biodiesel's cost is still higher than its petroleum counterpart, hence its production process must be modified to make it economically viable. Microalgae are an alternative feedstock to replace agricultural crops for biodiesel production, and offer several advantages such as fast growth, use of non-arable land, growth in saline and wastewater, and high lipid yield. Unfortunately, biodiesel production from microalgae is very energy-intensive and costly, mainly due to the high energy consumption required for dewatering and drying. Therefore, utilizing wet microalgal biomass instead of dry biomass can be a promising solution to reduce the biodiesel production cost Furthermore, the use of heterogeneous catalysts offers high efficiency, recoverability, and reusability, and is therefore very promising from the economic and environmental perspectives. The unique characteristics of graphene-based nano-catalysts, such as their high surface area, two-dimensional structure, and functional groups, make them suitable candidates for biodiesel production. In this review, the use of graphene-based catalysts for biodiesel production is analyzed in depth, and their efficiency compared to other heterogeneous catalysts is scrutinized. Moreover, their recoverability, reusability, and economic feasibility are critically discussed, and their potential to produce biodiesel from wet microalgae is explored as a sustainable and cost-effective approach.