Microwave-assisted transesterification for optimized biodiesel production from waste cooking oil using a heterogeneous base catalyst derived from Pila ampullacea shells

Due to increasing population growth, the consumption and needs of energy increase significantly. This leads Indonesia government to search alternative energy to cover the lacks of fossil energy reserves. Biodiesel is one of the prospective alternative energy which are renewable and environmental friendly. A common problem in large-scale biodiesel production is the sustainability of feedstock and the biodiesel stability. Therefore, the purpose of this study was to evaluate the production of biodiesel from two oil sources i.e. waste cooking oil and castor oil. This study examined the effect of mixed oil ratio on yield, biodiesel characteristics and stability. The physical properties included kinematic viscosity, acid number, saponification number, iodine number and cetane number have been evaluated as function of oil ratio. Yield of biodiesel was obtained at 35.07%, 99.2% and 83.69% for jatropha:castor oil ratio of 1: 0, 1: 2 and 2: 1, respectively. Most of these characteristics showed an increase by increasing the oil ratio. The result concluded that at the ratio of 1:1(v/v) was the best characteristic and stability.

The production of biodiesel from waste cooking oil (WCO) represents a sustainable and environmentally friendly approach to waste management and renewable energy generation. This study explores the use of calcium oxide (CaO) nanocatalyst in the transesterification process of converting WCO into biodiesel. CaO nanocatalyst is favored for its high catalytic activity, low cost, and environmental compatibility. In this study, calcium oxide (CaO)-based nano-catalyst was prepared through calcination process using local waste eggshells to produce biodiesel. The nano-CaO catalysis impact was investigated in a two-step transesterification chemical reaction from waste cooking oil (WCO) to biodiesel. Transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) techniques were utilized to confirm the CaO nano-catalyst. It was discovered that the CaO catalyst made from eggshell waste was an efficient, stable, and reasonably priced heterogeneous catalyst to be highly effective for the manufacture of biodiesel. The production of biodiesel was confirmed through FTIR analysis. Moreover, the biodiesel properties such as calorific value, specific gravity, acid value, density, flash point, kinematic viscosity, ash content, water content and cetane number were investigated and found to be similar with the EN 14214 biodiesel standard. It is expected that producing biodiesel using eggshell as a heterogeneous catalyst offers an economical and sustainable method of producing green fuel. This study underscores the potential of CaO nanocatalyst in enhancing the efficiency and sustainability of biodiesel production, offering a viable solution for waste management and energy production. J. of Sci. and Tech. Res. 6(2): 33-41, 2025

<abstract> <p>Petrodiesel is an unsustainable and undependable fuel owing to its environmental concerns and depleting reserves. Biodiesel is a sustainable alternative fuel to petrodiesel with a better fuel quality and minimum environmental impacts. However, cost-effective biodiesel production requires the use of a sustainable feedstock and process optimization. This study explored biodiesel yield optimization from mixed microalgae oil (MO) and waste cooking oil (WCO). The use of mixed feedstock for biodiesel production relieves the rising demands; lowers feedstock costs; and improves the fuel quality, engine performance, and pollutants emission characteristics. MO was extracted from dried microalgae biomass by the Soxhlet method using hexane. The MO and WCO were purified and characterized, and an oil blend with suitable properties (best in kinematic viscosity, density, higher heating value, and acid value compared to other blends) was selected. The transesterification experiments designed by central composite design were optimized using the response surface methodology. Experimental results underwent regression analysis to develop a quadratic model equation for predicting the optimum level of parameters and biodiesel yield. Model fitness and variables effects on biodiesel yield were studied using analysis of variance. The optimization experiment achieved 98.82% oil conversion rate at the catalyst loading of 2.0 w/v%, molar ratio of 12:1 v/v, reaction temperature of 60 ℃, and reaction time of 100 min. A triplicate validation experiments achieved 97.72% conversion rate, which is very close to the model predicted result (99.1%). Biodiesel from MO-WCO showed a better cetane number (77.76), iodine value (12.90 gI<sub>2</sub>/100 g), acid value (0.049 mg KOH/g), HHV (43.25 MJ/kg), kinematic viscosity (4.50 mm<sup>2</sup>/s), pour point (–2.5 ℃), and flash point (180 ℃). In conclusion, the study revealed that transesterification of blended MO-WCO led to a maximum biodiesel and the reaction time and temperature were found to be the most significant factors affecting the yield of biodiesel. Furthermore, biodiesel from blended MO-WCO is a sustainable and environmentally friendly alternative fuel source which can contribute towards a promising industrial scale biodiesel production in the future.</p> </abstract>

Biodiesel production from waste cooking oil: An efficient technique to convert waste into biodiesel

The global energy crisis and environmental concerns from fossil fuel use have driven the development of renewable biofuels. Biodiesel produced from waste cooking oil (WCO) is a promising option due to its low cost, wide availability, and non-competition with food resources. However, WCO typically contains high levels of free fatty acids (FFA), moisture, and impurities that hinder efficient conversion. This review highlights recent advances in process intensification strategies to improve WCO-based biodiesel production. Pretreatment methods such as heating, filtration, and centrifugation reduce contaminants, while acid esterification lowers FFA before transesterification. The physicochemical properties of WCO, particularly acid value and viscosity, are critical for setting optimal reaction conditions. Catalysts like NaOH (homogeneous), CaO from waste shells (heterogeneous), and bifunctional Mo₇-Zn₃/CaO are widely used to enhance reaction efficiency. Advanced reactors—especially microwave- and ultrasonic-assisted systems—significantly improve yield and energy efficiency. For instance, microwave-assisted transesterification using Mo₇-Zn₃/CaO achieves 94–96% biodiesel yield within 5–10 minutes at65 °C, reducing energy consumption by up to 40% compared to conventional methods. Most approaches meet ASTM D6751 and EN 14214 fuel quality standards. Life cycle assessments show that WCO biodiesel can reduce greenhouse gas emissions by 75–80% compared to fossil diesel. The use of waste-derived catalysts and recycling of by-products such as glycerol supports circular economy goals. Nonetheless, challenges like variable WCO quality and high capital costs for advanced reactors remain. Future work should focus on scalable reactor development, realtime monitoring, and supportive policy frameworks to promote sustainable biodiesel production at an industrial level.

The world's oil reserves are running low, which makes the government also implement a mandatory B30 policy starting in early 2020. With this policy, it is necessary to develop energy by utilizing renewable energy such as vegetable oil that can be converted into biodiesel. Waste cooking oil is one of the vegetable oils that has the potential to be processed into biodiesel because the use of waste cooking oil in Indonesia is still not developed. In this study, we report the yield of biodiesel from waste cooking oil with variations in the ratio of the number of moles and weight of heterogeneous catalysts. Biodiesel is made by esterification and transesterification with a heterogeneous catalyst (CaO), then a separation process is carried out to separate the biodiesel produced from the by-product in the form of glycerol. The separated biodiesel is then analyzed for density, viscosity, flash point, and pour point. The results showed that the best biodiesel was at a mole ratio of 1:24 with 3% CaO catalyst. Based on the analysis data, this biodiesel has the largest yield of 72.49% with a viscosity value of 4.9806 cSt, a flash point value of 72.5 oC, a pour point value of 0 oC, and a density value of 0.8662 g/ml and calorific value. 8837,302 cal/gram. With the results of the analysis, that are in accordance with the quality standards of SNI 7182:2015.

A cleaner process for biodiesel production from waste cooking oil using waste materials as a heterogeneous catalyst and its kinetic study

Hardly any neat biodiesel satisfies the European EN14214 standard for compression ignition engine application. To satisfy the EN14214 standard, various additives are doped into biodiesel; however, biodiesel additives might cause other problems such as increase in the particular emission and increased specific fuel consumption. In addition, the additives could be expensive. Considering the increasing level of greenhouse gas GHG emissions and fossil fuel depletion, it is forecasted that the use of biodiesel will be higher in the near future. Hence, the negative aspects of the biodiesel additives will likely to gain much more importance and need to be replaced with better solutions. This study aims to satisfy the European standard EN14214 by blending the biodiesels derived from sustainable feedstocks. Waste Cooking Oil (WCO) and Animal Fat Oil (AFO) are two sustainable feedstocks in the EU (including the UK) for producing biodiesels. In the first stage of the study, these oils were transesterified separately and neat biodiesels (W100 & A100) were produced. Secondly, the biodiesels were blended together in various ratios: 80% WCO biodiesel and 20% AFO biodiesel (W80A20), 60% WCO biodiesel and 40% AFO biodiesel (W60A40), 50% WCO biodiesel and 50% AFO biodiesel (W50A50), 30% WCO biodiesel and 70% AFO biodiesel (W30A70), 10% WCO biodiesel and 90% AFO biodiesel (W10A90). The prepared samples were analysed using Thermo Scientific Trace 1300 Gas Chromatograph and ISQ LT Mass Spectrometer (GC-MS). The GSMS analysis gave Fatty Acid Methyl Ester (FAME) breakdowns of the fuel samples. It was found that total saturation degree of the samples was linearly increasing (from 15% for W100 to 54% for A100) as the percentage of the AFO biodiesel was increased. Furthermore, it was found that WCO biodiesel was mainly (82%) composed of polyunsaturated FAMEs. Cetane numbers, iodine numbers, calorific values, lower heating values and the densities (at 15 oC) of the samples were estimated by using the mass percentages data of the FAMEs. Besides, kinematic viscosities (at 40 °C and 20°C), densities (at 15 °C), heating values and flash point temperatures of the biomixture samples were measured in the lab. It was found that estimated and measured characterisation results were comparable. The current study concluded that biomixture fuel samples W60A40 and W50A50 were perfectly satisfying the European EN 14214 norms without any need of additives. Investigation on engine performance, exhaust emission and combustion characteristics will be conducted to assess the full feasibility of the proposed biomixture fuels.

Biodiesel is an alternative fuel in the form of Fatty Acid Methyl Ester (FAME) which can be renewed using vegetable oils and animal oils through esterification or transesterification processes. This study used waste cooking oil as a raw material for biodiesel with a CaO catalyst from the shells of field snails (Pila ampullacea) which were calcined for 4 hours at a temperature of 700°C. This experiment aim to study of the effect of temperature (55°C, 60°C, 65°C) and catalyst weight (4%, 6%, 8%), for 2 hours the transesterification process and the molar ratio of oil to methanol was 1:9. Crude Biodiesel from the transesterification process washed using dry washing method with activated coconut shell charcoal which has been activated using 1M H3PO4. Based on this research, the optimum yields about 91,5%-volume, were obtained in A2T2 with temperature 60°C and a catalyst weight of 6% with a biodiesel yield of 91.5%. The characteristics of the biodiesel produced were kinematic viscosity 3.32 cSt, density 863 Kg/m3, acid number 0.543%, iodine number 14.3%-mass, methyl ester content 169.12% and cetane number 43.28%-mass.

Biodiesel is one of diesel fuel alternative made from renewable resources such as vegetable oils and animal fats. One of the natural ingredients that can be used as a material in the production of biodiesel is waste cooking oil (WCO). Biodiesel from WCO can be made through a transesterification reaction using a CaO catalyst. Free fatty acid (FFA) content in WCO needs to be reduced by activated charcoal adsorption. This research aims to determine the optimum time of adsorption by activated charcoal that made from salak peel and to determine the effect of transesterification temperature on biodiesel yield. The results showed that the FFA content of WCO decrease from 6.16% to 0.224% with adsorption time is 80 minutes and 10 gram of activated charcoal. Biodiesel yield increase by increasing transesterification temperature. The appropriate temperature is 50oC with 86.40% of yield, 887.2 kg/m3of density, 5.174 mm2/s of kinematic viscosity and acid number 0.421 mg KOH/gram sample. The composition of alkyl ester was obtained 65.54% with a FAAE yield of 56.63%.

Application of Crop-residue Biomass as a Catalyst for Bio-diesel Production from Waste Cooking Oil

This work investigated the optimisation of biodiesel production from waste cooking oil (WCO) and palm oil using a two-step transesterification process for WCO and base catalysed transesterification for palm oil. Transesterification reactions were carried out to investigate the effects of prepared catalyst CaO, methanol/WCO and methanol/palm oil ratio and temperature on the yield of biodiesel. A series of experiments were conducted to determine the best conditions for biodiesel production, using methanol/oil ratio between 4:1 and 11:1 and contact time varying between 2 and 4 h. Biodiesel yield of around 90 and 70% was obtained for palm and waste cooking oil at the methanol/oil ratios of 6:1 and 8:1 at temperature of 60 °C for reaction time of 4 h using prepared CaO as catalyst. The physicochemical properties of palm and WCO biodiesel were carried out using standard methods, while the fatty acid profile was determined using gas chromatography. The investigation concludes that biodiesel obtained from palm and waste cooking oil was within the specified limit.

Biodiesel is among one of the environment friendly and nontoxic alternative fuels that is acquired from renewable energy sources. Exploration of new methods for biodiesel production has become a key area of interest in research due to the environmental benefits of biodiesel and the fluctuating prices in fuel. The present work exemplifies the transesterification of used cooking oil to biodiesel. The feedstock was obtained from the mess of St. Joseph's College of Engineering, Chennai. The reactant used here was methanol and the base catalyst used was KOH. The study parameters were catalyst concentration, temperature, reaction time and methanol content. The characteristic properties of the produced biodiesel like Flash Point, Fire Point, Purity, Kinematic Viscosity, Ash, Calorific value, Cetane Number, Density, Acid value, Iodine Value was studied using various laboratory equipments. The biodiesel produced was blended with petroleum diesel to run the unmodified diesel engine which had an rpm of 1500. The emission of biodiesel was tested to be 1.32 and the smoke density was less than 1.58 which is petroleum diesel smoke density and this was approved by Regional transport officer.

Cooking conditions affect oil properties and consequently, the quality of the derived biodiesel. Nevertheless, little information regarding the impact of the cooking process on biodiesel properties is currently available, especially for palm biodiesel. Therefore, this study examined the effect of cooking temperature, time of use, and length of reuse, on selected properties of biodiesel produced from palm-based waste cooking oils (WCO). Several WCO collected from restaurants belonging to four categories, namely fried chicken restaurants, fast food restaurants, snack producers, and typical restaurants, were subjected to base-catalyzed transesterification. The biodiesel yield was calculated, and the produced biodiesel was characterized as to its kinematic viscosity, calorific value, and cetane number. As a result, palm-based WCO performed better than other WCO in terms of biodiesel yield regardless of the conditions that they experienced, achieving almost 95% in some cases. The yield decreased as the cooking temperature and length of reuse moved upward, whereas the kinematic viscosity was sensitive only to the length of reuse, rising with increasing reuse. Non-compliance with biodiesel standards and technical requirements was observed in a few cases. The calorific value did not significantly change unless the cooking conditions were severe. The cetane number dropped as use and reuse decreased, remaining better compared to petrodiesel (70.2 ± 3.2 on average). Typical restaurants would generate the most suitable WCO to produce biodiesel, i.e., yield: 93.1 ± 0.2%; kinematic viscosity: 5.0 ± 0.3 mm2/s; calorific value: 39.9 ± 0.1 MJ/kg; density: 919 ± 9 kg/m3; and cetane number: 67.4 on average. This is consistent with the less severe cooking conditions employed at these restaurants.

© 2018 ETA-Florence Renewable Energies. In this study, high acid value waste cooking oil (WCO) has been assessed for biodiesel production using supercritical methanol. A comparative analysis between two different WCOs with dissimilar total acid number (TAN) has been conducted. The main factors influencing the reaction have been analysed using Response Surface Methodology (RSM) including methanol to oil (M:O) molar ratio, reaction temperature, reaction pressure and reaction time. Biodiesel yield has been chosen as reaction responses for the comparative analysis. Using RSM, two quadratic models representing the interrelationships between reaction variables and biodiesel yield for both feedstocks have been developed. It has been observed that reaction variables have different effect on biodiesel yield in each feedstock. The optimal reaction conditions have been predicted using numerical optimisation for the WCO with higher TAN. The predicted optimal reaction conditions have been realised at M:O molar ratio, temperature, pressure and time of 25.5:1, 268°C, 110 bar and 21.5 min, respectively. Experiments have been carried out at the optimum conditions for both WCOs, where 97% biodiesel yield has been achieved using WCO with higher TAN while only 81% yield for WCO with lower TAN. These results illustrate the positively effect of FFA content on enhancing biodiesel production using supercritical methanol.