For the production of biodiesel from waste cooking oil with an acid value of 1.86 mg KOH/g, five heterogeneous catalysts—Ba(OH)₂, CaO, MgO, ZnO, and AlCl₃—were employed. To optimize the reaction parameters of each catalyst, the influence of crucial process variables, such as catalyst loading, methanol-to-oil ratio, and reaction duration, was investigated. In addition, the effect of acetone as a cosolvent toward the progress of biodiesel production and the reusability of the heterogeneous catalysts were also examined, and the data were statistically evaluated with a 95% confidence level. Ba(OH)₂ performed exceptionally well, with a 92 wt.% biodiesel yield, followed by CaO with an 84 wt.% yield. However, none of the results for MgO, ZnO, or AlCl₃ were adequate. In addition, regardless of the type of catalyst utilized, adding 20 vol.% acetone to the biodiesel manufacturing process led to an increase in output. Furthermore, every heterogeneous catalyst was reusable, but only Ba(OH)₂ and CaO produced a significant yield until the third cycle. The other catalysts did not produce yields of any significance.

The crude glycerol produced as a byproduct of transesterification synthesis has very few applications because it comprises of significant amounts of methanol, catalyst, and soap. On the other hand, transesterifications of highly acidic oil in the presence of an alkaline catalyst are problematic due to the presence of high amounts of free fatty acids. In this study, the free fatty acid level of high acid oil, which was initially determined to be 19.25%, was decreased to permit the direct production of biodiesel via glycerolysis with pure glycerol, making direct transesterification feasible. Through a process of purification, crude glycerol was refined to 92.5% purity. It was revealed that the physiochemical parameters of density, moisture content, ash content, matter organic non-glycerol content, pH, and Na/K concentrations of generated purified glycerol are equal to those of commercially available glycerol. In contrast, glycerolysis treatment successfully decreased the free fatty acid level to less than 2% under optimal conditions, which were determined to be 200 °C, a glycerol-to-oil molar ratio of 4:1, and a KOH catalyst concentration of 1.6 wt.% at 350 rpm. The inclusion of hexane as a co-solvent accelerated the glycerolysis process, and the weight ratio of oil-to-hexane was 8:1. Moreover, it was viable to use waste methanol for biodiesel synthesis and purified crude glycerol as a raw material in a variety of industries, including biodiesel production. In addition, compared to acid esterification, the FFA concentration of oil with a high acid value fell significantly.

The present world highly depends on petroleum fuels to gain energy for transportation resulting in the vast side of environmental problems such as global warming and air pollution. Due to this, the price of conventional fuel escalating day by day. Accordingly, the world needs renewable, ecologically suitable, cost-effective alternate against fossil fuels. Bioethanol is one of the most usable fuel or fuel additives among the other biofuels. Ingoing qualities of bioethanol such as high-octane number, high oxygen content, and low energy content are revealed that application of bioethanol produced from different types of waste materials feedstock in the transportation and energy sector diminishes environment pollution. It provides a solution for waste management. The world releases a considerable amount of fruits as waste annually. Thereby, fruit waste is the cheapest feedstock to produce bioethanol. Fruit waste such as whole rotten fruits, fruit peels, seeds and other residues consists of cellulose, hemicellulose, lignin, starch and simple sugars. Conversion of cellulose and hemicellulose to ethanol is vital to advance pretreatment and hydrolysis techniques to obtain maximum ethanol content. The production process of bioethanol from fruit waste mainly contains pretreatment; hydrolysis, saccharification, fermentation and ethanol extracting process (distillation) steps. Yeast (S. cerevisiae) is primarily used in the fermentation process because of its high conversion efficiency, cost-effectiveness and feasibility of handling. Considering the optimum configuration for bioethanol production, simultaneous saccharification and fermentation (SSF) is the best commensurate method having maximum bioethanol concentration. The fermentation process could be appreciated through various factors, such as temperature (30-33 ºC), pH of the medium (4-5), time of incubation, feedstock concentration, inoculum size, agitating rate, N sources in the medium to gain high bioethanol concentration.

Biodiesel is an excellent substitute for fossil diesel, which received a significant attention in recent decades. Catalyst methods are frequently used to produce biodiesel at low temperatures and pressures. The present work investigates the methanolysis of waste cooking oil with the acid value of 1.86 mg KOH/g employing a variety of homogeneous base catalysts, including KOH, NaOH, CH3OK and CH3ONa. Among the studied catalysts, CH3OK produced the highest biodiesel yield at 99.0%, followed by CH3ONa, KOH and NaOH under the identical reaction conditions. The reaction was carried out for 30 min at 600 ºC and a speed of 600 rpm with a molar ratio of 6:1 for methanol-to-waste cooking oil (WCO) and a 1 wt.% catalyst. However, the viscosity, flash point, density and acid value of the biodiesel all met ASTM criteria, indicating that biodiesel made from KOH, NaOH, CH3OK and CH3ONa is of high quality.

Energy production relies on finite fossil fuels and is usually regarded as the primary source of hazardous emissions and global warming. As a result, much attention has been dedicated to biofuel as a fuel for engine alternatives. Biofuel is now primarily utilized in blends with fossil diesel. As a result, this study was focused on adding bioethanol and biodiesel to fossil diesel. Biodiesel was manufactured by transesterification from waste cooking oil, while bioethanol was made through banana fermentation. The physical properties such as density, kinematic viscosity, flashpoint, and cetane index of fossil diesel-biodiesel-bioethanol blends were compared with fossil diesel fuel in laboratory experiments. When added, bioethanol was found to degrade the physical properties of blended fuels substantially. The substitution of bioethanol for fossil diesel resulted in a significant reduction of hazardous emissions. The assessment of flue gas emissions indicated a considerable reduction in CO2, CO, hydrocarbon (HC) and NOx emissions.

Biodiesel is a renewable fuel with similar chemical and physical properties to diesel. The study used waste cooking oil to make biodiesel because reusing waste cooking oil harms human health by raising FFA levels above the norm. Transesterification was performed at 60 °C using a 1:5 methanol to waste cooking oil volume ratio, 30 min reaction time, 600 rpm stirring speed and 1% wt. KOH was employed as a homogenous base catalyst. Biodiesel samples of B0, B2, B5, B20, B40 and B100 were processed at 25 ºC in combination with petrodiesel. Samples were tested for density, kinetic viscosity, flash point, acid value and pH. The fuel economy and flue gas analysis were performed using three-wheeler diesel. The amount of waste cooking oil biodiesel increases the density, kinematic viscosity, flash point, acid value and pH of the sample. In blended diesel, the amount of biodiesel also lowered CO2, CO, NO, NOx, hydrocarbon (HC) and SO2 emissions.