Ethanolysis of Waste Cooking oils using KOH Catalyst

The transesterification of waste cooking oils (WCO) with ethanol was investigated by means of potassium hydroxide (KOH) as catalyst. This work aimed to study the influences of catalyst concentration, temperature, ethanol to WCO molar ratio, reaction time, and stirring rate on the biodiesel conversion. Gas chromatography (GC) was used during the process of transesterification to determine the evolution of ethyl esters concentration with time. Biodiesel with maximum yield was obtained (92.5%) when 2 wt% KOH, temperature of 75°C, and ethanol/oil molar ratio of 11:1 were utilized.

Turning Waste Cooking Oils into Biofuels—Valorization Technologies: A Review

In search of a more sustainable society, humanity has been looking to reduce the environmental impacts caused by its various activities. The energy sector corresponds to one of the most impactful activities since most energies produced come from fossil fuels, such as oil and coal, which are finite resources. Moreover, their inherent processes to convert energy into electricity emit various pollutants, which are responsible for global warming, eutrophication, and acidification of soil and marine environments. Biofuels are one of the alternatives to fossil fuels, and the raw material used for their production includes vegetable oils, wood and agricultural waste, municipal waste, and waste cooking oils (WCOs). The conventional route for WCO valorization is the production of biodiesel, which, as all recovery technologies, presents advantages and disadvantages that must be explored from a technical and economic perspective. Despite its successful use in the production of biodiesel, it should be noticed that there are other approaches to use WCO. Among them, thermochemical technologies can be applied to produce alternative fuels through cracking or hydrocracking, pyrolysis, and gasification processes. For each technology, the best conditions were identified, and finally, projects and companies that work with this type of technology and use WCO were identified.

Catalytic Conversion of Glycerol into Hydrogen and Value-Added Chemicals: Recent Research Advances

In recent decades, the use of biomass as alternative resources to produce renewable and sustainable biofuels such as biodiesel has gained attention given the situation of the progressive exhaustion of easily accessible fossil fuels, increasing environmental concerns, and a dramatically growing global population. The conventional transesterification of edible, nonedible, or waste cooking oils to produce biodiesel is always accompanied by the formation of glycerol as the by-product. Undeniably, it is essential to economically use this by-product to produce a range of valuable fuels and chemicals to ensure the sustainability of the transesterification process. Therefore, recently, glycerol has been used as a feedstock for the production of value-added H2 and chemicals. In this review, the recent advances in the catalytic conversion of glycerol to H2 and high-value chemicals are thoroughly discussed. Specifically, the activity, stability, and recyclability of the catalysts used in the steam reforming of glycerol for H2 production are covered. In addition, the behavior and performance of heterogeneous catalysts in terms of the roles of active metal and support toward the formation of acrolein, lactic acid, 1,3-propanediol, and 1,2-propanediol from glycerol are reviewed. Recommendations for future research and main conclusions are provided. Overall, this review offers guidance and directions for the sufficient and economical utilization of glycerol to generate fuels and high value chemicals, which will ultimately benefit industry, environment, and economy.

Polyhydroxyalkanoates (PHAs), bioprocessing using waste oil

Pseudomonas oleovorans NCIMB 6576 and Ralstonia eutropha NCIMB 10442 were used for the production of Polyhydroxyalkanoates (PHA) from industrial waste cooking oils, the bacteria were cultured on tryptone soya broth (TSB) and Tryptone soya agar (TSA). P. oleovorans NCIMB6576 gave a better percentage PHB yield (8.2%) with PS oil as carbon source as compared to 6.45% with TS oil. However, a very low yield (0.64%) was recorded when P. oleovorans NCIMB6576 was grown on TSB without the oils as carbon source. Ralstonia eutropha NCIMB 10442 gave an appreciable yield of 13.63% and 14.80% with PS and TS oil samples respectively as carbon source with negligible variation in the yields. The results obtained across all experiments were compared with one another. The SEM images from the PHB samples generated from the experiments shows that there is a slight difference in the surface morphologies of the PHB with respect to the oil samples as well as the different bacteria used in the experiment.

Glycolipid Biosurfactant Production from Waste Cooking Oils by Yeast: Review of Substrates, Producers and Products

Biosurfactants are a microbially synthesized alternative to synthetic surfactants, one of the most important bulk chemicals. Some yeast species are proven to be exceptional biosurfactant producers, while others are emerging producers. A set of factors affects the type, amount, and properties of the biosurfactant produced, as well as the environmental impact and costs of biosurfactant’s production. Exploring waste cooking oil as a substrate for biosurfactants’ production serves as an effective cost-cutting strategy, yet it has some limitations. This review explores the existing knowledge on utilizing waste cooking oil as a feedstock to produce glycolipid biosurfactants by yeast. The review focuses specifically on the differences created by using raw cooking oil or waste cooking oil as the substrate on the ability of various yeast species to synthesize sophorolipids, rhamnolipids, mannosylerythritol lipids, and other glycolipids and the substrate’s impact on the composition, properties, and limitations in the application of biosurfactants.

Biodiesel Production from Waste Cooking Oil: Characterization, Modeling and Optimization

In this study, waste and discarded cooking oils (WCO) of palm, sunflower, rice bran and groundnut oils are collected from local restaurants. The high viscous WCO was converted into waste cooking oil biodiesel (WCOBD) by a single-stage transesterification process. During the transesterification process, the important parameters which show a significant change in biodiesel yield are studied using the optimization tool of response surface methodology (RSM). Results reported that 91.30% biodiesel yield was achieved within L18 experiments and NaOH catalyst was identified as the most influential parameter on WCOBD yield. Artificial Intelligence (AI) based modeling was also carried out to predict biodiesel yield. From AI modeling, a predicted yield of 92.88% was achieved, which is 1.70% higher than the RSM method. These results reveal the prediction capabilities and accuracy of the chosen modeling and optimization methods. In addition, the significant fuel properties are measured and observed within the scope of ASTM standards (ASTMD6751) and fatty acid profiles from chromatography reveal the presence of high unsaturated fatty acids in WCOBD. Therefore, utilizing the waste cooking oils for biodiesel production can mitigate the global challenges of environmental and energy paucity.

Waste cooking oils as processing aids for eco-sustainable elastomeric compounding

This work focuses on the replacement of mineral oils with bio-based waste cooking oils in rubber compounding. Two different waste cooking oils from potatoes and chicken frying process were analyzed by means of chemical and rheological tests to evaluate the chemical composition, the oxidative stability and the viscosity. Waste oils have been introduced in elastomeric compounds as substitute for typical processing aids (i.e. lubricants). Cure kinetics of rubber compounds was studied by rheological characterization. Mechanical properties of vulcanized samples were determined by means of tensile tests, hardness tests and dynamic mechanical analysis. The waste oils showed a rheological behavior very similar to the mineral oils conventionally employed in rubber manufacturing leading to almost the same processability of the resulting compound. The waste oils did not significantly affect the vulcanization kinetics of the rubber compound, as expected for conventional lubricants. Waste cooking oils and mineral oil show analogous influence on mechanical properties of cured compounds. At increasing oil content, the elongation at break and the tensile strength increased whereas the values of Elastic Modulus at 100% strain, the Storage Modulus and Shore A Hardness decreased with respect to the oil-free sample. These results are very promising, confirming the possibility to replace the mineral oils, in a good practice of circular economy.