Welela Meka Kedir

Biodiesel can be produced using domestic resources like straight vegetable oil, animal fats, and waste cooking oil. Its use, instead of conventional diesel, contributes to the reduction of CO2 emissions. The production of biodiesel through transesterification (TE) reactions requires adequate catalysts to speed up the reactions. The classical methods of biodiesel production were conducted using homogeneous catalysts, which have drawbacks such as high flammability, toxicity, corrosion, byproducts like soap and glycerol, and a high wastewater output. Recently, various types of heterogeneous catalysts and continuous reactors have been invented for the production of biodiesel. As a result, the initial choice of catalysts is crucial. However, it is also affected by the amount of free fatty acids in a given sample of oil. In addition, most of the catalysts are not suitable for large-scale industrial applications due to their high cost. Bifunctional heterogeneous catalysts are widely applicable and have a rich history of facilitating energy-efficient, selective molecular transformations, and contributing to chemical manufacturing processes like biodiesel. This chapter underlines the use of bifunctional heterogeneous catalysts for biodiesel production using low-cost feedstock. Furthermore, it examines the sustainability of catalysts and low-cost feedstock for large-scale biodiesel production. Finally, the chapter indicates a further perspective of biodiesel as an alternative fuel using low-cost feedstock and recommends a sustainable bifunctional heterogeneous catalyst for biodiesel production.

Ginger is a medicinal plant widely used as a spice and botanically categorized in the Zingiberaceae family, Zingiber genus, and officinale species. Natural and anthropogenic sources can discharge heavy metals into the environment from which they enter the human body through food, water, air, and skin contact and cause detrimental health effects. In this study, ginger samples were randomly collected from five kebeles in Ilubabor and Bunno Bedelle zones, Southwest Ethiopia, from which a composite sample was made for analysis. Microwave-assisted digestion was carried out using concentrated nitric acid in the presence of hydrogen peroxide followed by atomic absorption spectrometer detection using different Association of Analytical Chemists, AOAC methods. Proximate analysis was performed with different standard operating procedures. The mean levels of heavy metals were 0.009 mg/kg for Arsenic, Chromium, and Lead and 0.01 mg/kg for cadmium while 578.2 mg/kg was obtained for iron. Proximate composition analysis shows 82.89%, 2.00%, 0.07%%, 1.63%, 3.42%, 9.99%, and 48.59 kcal for moisture, crude protein, crude fat, ash, crude fiber, carbohydrate, and energy, respectively. The validated method had acceptable linearity (R² = 0.9978 - 0.9993), the limit of detection (8.18x10^-5 - 0.0075), the limit of quantification (2.7x10^-4 - 0.025), recovery (75 - 106.87%) and precision (4.77 - 13.97 %). The hazard index (HI) of the metals was less than one showing insignificant non-carcinogenic risk from exposure to a single or multiple possibly toxic elements from the studied ginger samples.

Domestic resources such as vegetable oil, animal fats, tallows, and waste frying oil are common raw materials for making biodiesel. In contrast to ordinary diesel, biodiesel helps to reduce CO2 emissions. This study aimed to produce biodiesel using waste frying oil in the presence of suitable solid waste-derived heterogeneous catalysts. Firstly, CaO/K2O catalyst was synthesised using eggshells and banana peels. Then, the pre-prepared catalyst (CaO/K2O) modified with ZnO was utilized for biodiesel production. The prepared catalyst and biodiesel were characterized using X-ray diffraction (XRD) and FTIR spectroscopy. The AOAC and ASTM standard methods were employed to analyze the physicochemical properties of oils and biodiesel. The catalytic efficiency of CaO/K2O and CaO/K2O-ZnO tested for the transesterification of purified oil to biodiesel at the catalyst weight (1-7 %wt), temperature (60-80°C), and methanol to oil ratios ranging from 3:1 to 12:1. The highest biodiesel yield (92%) obtained when 5 %wt CaO/K2O catalyst used. However, a 95% yield resulted when using a 3 %wt CaO/K2O-ZnO catalyst load in 2 h with a methanol to oil (v/v) ratio of 9:1 at 65°C. The study revealed that waste frying oil is a good source of biodiesel which could replace nonrenewable energy in the future. The catalysts made from solid waste could also replace an expensive chemical catalyst.

The kidney is the organ most vulnerable to nephrotoxic drugs such as gentamicin. Nephrotoxicity is a rapid deterioration of kidney function due to various factors. Gentamicin causes nephrotoxicity, which was manifested by an increase in serum kidney biomarkers. Asparagus africanus is one of the ethnomedicinal plants used as traditional medicine for treating various ailments, including kidney disease in Ethiopian society. Thus, the aim of this study is to evaluate the nephroprotective effect of A. africanus root extract on gentamicin-induced nephrotoxicity. Using maceration techniques, 100 g of dried plant powder was extracted in 1 L of ethanol. The physicochemical screening of plant extracts revealed the presence of flavonoids, phenols, tannins, saponins, and steroids. The nephroprotective activity of A. africanus crude extract was evaluated on male Swiss albino mice. The crude ethanolic extract at 200 and 400 mg/kg doses showed strong nephroprotective effects by restoring biomarkers such as creatinine, uric acid, and blood urea nitrogen, which were damaged by gentamicin ( ) in a dose-dependent manner. The mice treated with higher doses (400 mg/kg) had a comparable nephroprotective effect compared to the positive control group (200 mg/kg silymarin; ). The histopathology of the control group showed normal glomeruli, normal parenchyma, distal convoluted, and no tubular damage. The toxicant-induced group showed damage to glomeruli and inflammatory infiltration. Therefore, A. africanus root extract has a nephroprotective activity by retarding the gentamicin toxicity in male Swiss albino mice.