Evaluation of various waste cooking oils for biodiesel production: A comprehensive analysis of feedstock

Biodiesel production and properties estimation from food waste and domestic wastewater by Rhodosporidium toruloides

Producing biodiesel from food waste (FW) would benefit both environment and economy. Current study investigated biodiesel production from food waste and domestic wastewater by utilizing the oleaginous yeast Rhodosporidium toruloides under non-sterile condition. The potential of biolipid production from the mixture of effluents of existing local FW treatment facilities and domestic wastewater was firstly evaluated. Then, to increase the nutrient recovery efficiency, FW hydrolysis process by crude enzymes produced from solid FWs by Aspergillus oryzae was introduced and the conditions were further optimized. The optimized hydrolysis process resulted in reducing sugar (RS) yield of 251.81 ± 8.09 mg gdryFW-1 and free amino nitrogen (FAN) yield of 7.70 ± 0.74 mg gdryFW-1 while waste oil with the RS yield of 93.54 ± 0.01 mg gdryFW-1 was easily separated without solvent usage. Compared to the hydrolysate only used, when mixed with domestic wastewater, the results showed obvious enhancement on biomass yield, biolipid yield, and wastewater treatment efficiency. The maximum biolipid yield was 29.80 ± 0.50 mg gdryFW-1 and the estimated quality of biodiesel produced from the biolipid met both EN 14214 and ASTM D6751 standards.

Performance of bio-asphalts: state of the art review

The global population spike, rise in industrialization, and highway infrastructure development induce focus on sustainable development. The ever-increasing consumption of non-renewable crude oil and asphalt levies a heavy toll on economic welfare of future generations. This enormous demand of asphalt is due to its wide applicability in flexible pavements. Therefore, the construction industry is exploring the partial substitution of renewable materials in asphalt with a focus on economical, social, and environmental benefits. The current decade has seen a rampant rise of bio-asphalt as an alternative to asphalt. Hence, it is imperative to explore the performance of bio-asphalt for its sustainable applicability. This review comprehensively summarizes the performance of bio-asphalt obtained from various biomass sources. It deals with elemental composition of bio-oil, preparation procedure, rheological performance, mixture performance, and aging mechanism of bio-asphalt along with modification required to improve the performance. The environmental impacts and field application of the bio-asphalts are also discussed.

Tungsten oxide supported on copper ferrite: a novel magnetic acid heterogeneous catalyst for biodiesel production from low quality feedstock

This study aims to synthesize a WO₃/CuFe₂O₄ catalyst through a wet impregnation method and use it as a new magnetic acid catalyst in the transesterification process of waste cooking oil (WCO). The results of the characterization by XRD, FTIR, SEM, EDS, TG/DTG, VSM and Surface Acidity showed that the obtained bifunctional catalyst has been successfully synthesized. The study of the reaction parameters, such as reaction temperature (140-180 °C), reaction time (1-5 h), molar ratio MeOH : oil (25 : 1-45 : 1) and catalyst loading (2-10% m m^-1) was performed in the conversion of WCO into biodiesel via transesterification. The reactional behavior showed the following optimal reaction conditions: reaction temperature of 180 °C, reaction time of 3 h, molar ratio MeOH : oil of 45 : 1 and catalyst loading of 6%. Based on the results, biodiesel with a maximum ester content of 95.2% was obtained using the WO₃/CuFe₂O₄ magnetic catalyst under the optimal reaction conditions. The magnetic catalyst showed excellent catalytic and magnetic performance and it was applied in five reaction cycles with ester content above 80%. Biodiesel properties were found in accordance with ASTM limits. This research provided the development of a stable and reusable WO₃/CuFe₂O₄ bifunctional catalyst for potential application in biodiesel production.

Life cycle assessment of biodiesel production by using impregnated magnetic biochar derived from waste palm kernel shell

Biodiesel is renewable, biodegradable, biocompatible (non-toxic) and environmentally friendly, which emits less pollution than traditional fossil-based diesel, making it the most promising and ideal option. However, biodiesel is facing many current issues, mostly related to the utilisation of homogeneous catalytic technology, and this circumstance obstructs its potential development and advancement. Therefore, new pathways for biodiesel production need to be explored, and the aforementioned issues need to be addressed. Recently, a study was conducted on the impregnated magnetic biochar derived from a waste palm kernel shell (PKS) catalyst that can replace conventional catalysts due to its reusability property. Nevertheless, the environmental impacts of impregnated magnetic biochar derived from waste PKS catalyst for biodiesel production are yet to be studied. This study focuses on the evaluation of the life cycle assessment (LCA) of palm-based cooking oil for biodiesel production catalysed by impregnated magnetic biochar derived from waste PKS. Simapro was used in this study to evaluate the impact assessment methodologies. Case 1 (6.64 × 10² Pt) has contributed less to environmental impacts than Case 2 (1.83 × 10³ Pt). This indicates purchasing refined palm oil for biodiesel production may reduce environmental impacts by 64% compared to producing biodiesel from raw fruit bunches. In the midpoint assessment, the transesterification process was identified as the hotspot and marine aquatic ecotoxicity as the highest impact category with a value of 1.00 × 10⁶ kg 1,4-DB eq for 1 tonne of biodiesel produced. The endpoint results showed that Case 1 revealed the greatest impact on the transesterification process, with cumulative damage of 461 Pt. Scenario without processing the raw palm fruit bunches to obtained palm oil was better than Case 2. Further research should be conducted on life cycle cost and sensitivity analysis to evaluate the economic feasibility and promote sustainable biodiesel production.

Enhanced waste hot-pot oil (WHPO) anaerobic digestion for biomethane production: Mechanism and dynamics of fatty acids conversion

Resource depletion and climate changes due to human activities and excessive burning of fossil fuels are the driving forces to explore alternatives clean energy resources. Anaerobic digestion of bio-waste provides a unique opportunity to fulfil this objective through biogas production. The present study aimed to evaluate waste hot-pot oil (WHPO) at different feeding ratios as a novel lipidic waste for anaerobic mono-digestion. The highest recorded maximum biomethane potential (M_max) was 274.1 L kg^-1 VS at 1.2% WHPO, which showed significant differences with those of 0.8% and 1.6% (227.09 and 237.62 L kg^-1 VS, respectively). The changes in volatile fatty acids (VFAs), medium chain fatty acids (MCFAs), and long-chain fatty acids (LCFAs) as intermediates of WHPO decomposition were investigated before and after anaerobic digestion. Results showed efficient production and utilization of VFAs at all studied WHPO ratios, whereas the maximum utilization of VFAs (90-95%) was recorded in the reactors with up to 1.2 %WHPO. Although lipid conversion efficiency decreased by increasing the WHPO ratio, 81.2% lipid conversion efficiency was recorded at the highest applied WHPO treatment, which confirms the potential of WHPO as a promising feedstock for anaerobic digestion. The present results will have major implications towards efficient energy recovery and biochemical management of lipidic-waste through efficient anaerobic digestion.

Effects of the Degree of Unsaturation of Fatty Acid Esters on Engine Performance and Emission Characteristics

Biodiesel is considered an environmentally friendly alternative to petro-derived diesel. The cetane number indicates the degree of difficulty in the compression-ignition of liquid fuel-powered engines. The allylic position equivalent (APE), which represents the unsaturated degree of fatty acid esters, was one of the key parameters for the cetane number of biodiesel. Due to the significant attributes of APE for biodiesel properties, the impact of APE on engine performance and emission characteristics was investigated in this study. The engine characteristics could be improved by adjusting the biodiesel fuel structure accordingly. A four-stroke and four-cylinder diesel engine accompanied by an engine dynamometer and a gas analyzer were used to derive the optimum blending ratio of the two biodiesels from soybean oil and waste cooking oil. Three fuel samples composed of various proportions of those two biodiesels and ultra-low sulfur diesel (ULSD) were prepared. The amounts of saturated fatty acids and mono-unsaturated fatty acids of the biodiesel made from waste cooking oil were significantly higher than those of the soybean-oil biodiesel by 9.92 wt. % and 28.54 wt. %, respectively. This caused a higher APE of the soybean-oil biodiesel than that of the biodiesel from waste cooking oil. The APE II biodiesel appeared to have the highest APE value (80.68) among those fuel samples. When the engine speed was increased to 1600 rpm, in comparison with the ULSD sample, the APE II biodiesel sample was observed to have lower CO and O2 emissions and engine thermal efficiency by 15.66%, 0.6%, and 9.3%, while having higher CO2 and NOx emissions, exhaust gas temperature, and brake-specific fuel consumption (BSFC) by 2.56%, 13.8%, 8.9 °C, and 16.67%, respectively. Hence, the engine performance and emission characteristics could be enhanced by adequately adjusting the degree of unsaturation of fatty acid esters represented by the APE of biodiesel.

Biodiesel and Bioplastic Production from Waste-Cooking-Oil Transesterification: An Environmentally Friendly Approach

Alternative sources of fuel have been a concern in the last few decades. The growth of urbanization and industrialization will lead to the exhaustion of fossil fuels, attracting studies on alternative routes. The main aim of this study was to produce biodiesel from waste cooking oil (WCO) by methyl transesterification using sodium hydroxide as a catalyst. For this, the physicochemical parameters of biodiesel were studied in triplicate (density, acidity, saponification, viscosity, corrosiveness to copper, visual appearance, and cloud point). An analysis by thin layer chromatography and infrared spectrometry was also performed. The increase in yield (83.3%) was directly proportional to the increase in the catalyst (0.22 g of NaOH). The infrared absorption spectra of WCO and biodiesel showed the presence of common and singular bands of each material. Furthermore, a simple and low-cost mechanism was proposed for purifying glycerol. The spectra of glycerol versus purified glycerin showed that the glycerin produced was pure, being used in the formulation of bioplastic. The product was checked for biodegradation and photodegradation, with incredible soil-degradation times of 180 days and photodegradation of only 60 days. In this way, biodiesel production from WCO showed environmentally friendly proposals and applicability. As the next steps, it is necessary to test the biodiesel produced in combustion engines and improve the bioplastic production, including a spectroscopic characterization and extensive biodegradation testing.

Synthesis and properties of wax based on waste cooking oil

In this work, a cost-effective wax was synthesized from waste cooking oil (WCO), and its properties including melting point, color, hardness, combustion performance and micro-morphology were tested and analyzed. The obtained results showed that the epoxy waste cooking oil had lighter color, higher melting point and hardness than that of original WCO, which could be used as wax. Moreover, introducing stearic acid further improved the performances of WCO-based wax. The WCO-based wax made of epoxy waste cooking oil and stearic acid (containing ≥50 wt% stearic acid) displayed a relatively high melting point (≥46 °C), light color (Lovibond color code Y ≤ 16.1, R ≤ 2.3), good hardness (needle penetration index ≤2.95 mm) and long combustion time (≥227 min), and could achieve the required national standard and be used as a substitute for the commercially available soybean wax. Together with many additional benefits such as low synthesis cost, mild reaction conditions, convenient synthesis route, and no secondary pollution, producing wax based on WCO could provide a new path for WCO recycling in economically trailing regions.

Low-cost wax based on waste cooking oil (WCO) was synthesized and could be a substitute for commercial soybean wax.