Optimum Conditions For Biodiesel Production Research Articles

Eco-friendly production of biodiesel from Carthamus tinctorius L. seeds using bismuth oxide nanocatalysts derived from Cannabis sativa L. Leaf extract

Global challenges in environmental protection, social welfare, and economic growth necessitate increased energy production and related services. Biofuel production from waste biomass presents a promising solution, given its widespread availability. This study focuses on converting highly potent Carthamus tinctorius L. seed oil (51 % w/w) into sustainable biofuel using a novel, highly reactive, recyclable, and eco-friendly bismuth oxide (Bi2O3) nano-catalyst derived from Cannabis sativa L. leaf extract. The physio-chemical properties of the synthesized biodiesel were analyzed using Gas Chromatography/Mass Spectroscopy (GC-MS), Nuclear Magnetic Resonance (NMR), and Fourier-Transform Infrared Spectroscopy (FTIR). Additionally, the green Bi2O3 nanoparticles were characterized through Scanning Electron Microscopy (SEM), Energy Diffraction X-Ray (EDX), and X-Ray Diffraction (XRD). Optimal conditions for biodiesel production were determined using Response Surface Methodology (RSM) in combination with Central Composite Design (CCD), focusing on molar ratio, catalyst loading, and reaction duration. The highest output (94 %) of C. tinctorius-derived biodiesel (CTBD) was achieved under the following conditions: a temperature (75 °C) for time duration (100 min), a methanol to oil ratio (6:1), and a catalyst loading (0.69 wt%). The resulting biodiesel met international standards, with a sulphur content of 0.00097 wt%, and an acid value of (0.34 mg KOH/g). This study demonstrates that converting C. tinctorius waste seed oil into clean bioenergy is an effective waste management strategy that minimizes environmental impact.

Optimization of Enzymatic Transesterification of Acid Oil for Biodiesel Production Using a Low-Cost Lipase: The Effect of Transesterification Conditions and the Synergy of Lipases with Different Regioselectivity.

This study describes the enzymatic production of second-generation biodiesel using low-quality acid oil as a substrate. Biolipasa-R, a commercially available and low-cost lipase, was employed for enzymatic transesterification. Response surface methodology was applied to optimize the enzymatic transesterification process. The optimal conditions for biodiesel production, which comprised 42% lipase concentration (per weight of oil), 32% water content (per weight of oil), a methanol to oil molar ratio of 3:1, pH 7.0 and reaction temperature 30°C, resulted in the highest fatty acid methyl ester (FAME) content (71.3%). Subsequently, the synergistic effect of two lipases with different regioselectivities under the optimum transesterification conditions was studied, aiming at the enhancement of process efficiency. The transesterification efficiency of immobilized Biolipasa-R was determined and compared to that of Biolipasa-R in its free form. The results revealed a good performance on FAME content (66.5%), while the recycling of immobilized lipase resulted in a decrease in transesterification efficiency after three consecutive uses.

Manufacturing Biodiesel from Cooking Oil Teaching Factory Products Using Bentonite Catalyst with Non-Alcohol Route Method

This research investigates an eco-friendly approach to biodiesel production through non-alcoholic pathways using heterogeneous catalysts. The study examines various ratios of methyl acetate to cooking oil and temperatures, revealing that the optimal conditions for biodiesel production are a 1:4 ratio, utilizing a bentonite catalyst (0.75 g), operating at 60°C for 120 minutes. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirms the presence of ester groups, the primary component of biodiesel. Most biodiesel characteristics align with quality standards, including density (0.8844 kg/m3), cetane number (61.9), and acid number. However, the biodiesel flash point falls below the minimum standard, suggesting a potential area for improvement. This research underscores the potential of using methyl acetate as a heterogeneous catalyst for biodiesel production, with most biodiesel characteristics meeting established quality standards, although further work may be needed to address the flash point issue.

PTIMIZATION AND CHARACTERIZATION OF USED COOKING OIL FOR BIODIESEL PRODUCTION USING RESPONSE SURFACE METHODOLOGY

This study focuses on optimizing and characterizing alkali-catalyzed biodiesel production from used cooking oil. Transesterification using potassium hydroxide (KOH) and methanol, followed by solvent-solvent extraction, yielded biodiesel. Physicochemical analysis of the used cooking oil revealed an acid value of 29 mgNaOH/g, free fatty acid (FFA) value of 14.5, and density of 0.91 g/cm3. The high FFA content suggests the use of a heterogeneous catalyst. Optimization parameters included alcohol-to-oil ratio, catalyst concentration, reaction temperature, and time, employing Response Surface Methodology (RSM) based on Central Composite Design (CCD). Optimal conditions for biodiesel production were determined at a reaction temperature of 60°C, a reaction time of 60 minutes, 0.3g KOH catalyst concentration, and a 3:20 methanol-to-oil ratio, predicting a 100% yield. Physiochemical properties of the produced biodiesel indicated specific gravity and pH values of 0.891 and 7.60, respectively. Biodiesel blends (B100, B80, and B20) exhibited specific gravity and pH values of 0.891, 0.842, and 0.839, and 7.60, 7.81, and 5.5, respectively. Comparative analysis with diesel suggests the biodiesel's suitability for standalone or blended use in diesel engines. Characterization involved physicochemical analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Thin Layer Chromatography (TLC). Overall, the optimized process presented a viable and efficient approach to producing biodiesel from used cooking oil with favourable fuel properties

Biodiesel production from mahua oil: characterisation, optimisation, and modelling with a hybrid statistical approach

Present study investigates the feasibility of utilising mahua oil as a feedstock for the production of high-quality biodiesel via the transesterification process. Mahua fruit kernels offer an excellent biodiesel source, with an oil content of approximately 35–40%. This study employs a hybrid statistical approach, combining Response Surface Methodology (RSM) and Genetic Algorithm (GA), to optimise the transesterification process. Through the execution of L31 pre-designed experiments, this work analyzes the significance of four key process parameters: methanol-to-oil ratio, catalyst concentration, reaction temperature, and reaction time. The collective influence of these parameters on biodiesel production is comprehensively examined. The GA-derived optimal conditions for biodiesel production are determined as a molar ratio of 7.28 with a 0.93 wt.% catalyst concentration, a reaction temperature of 59.43°C, and a reaction time of 113.62 min. Experimental results validate the model predictions, as the actual yield of Mahua biodiesel reaches 97.54%, with a deviation of only 2.82% from the predicted value. Furthermore, the fuel characteristics of Mahua methyl ester were assessed and compared to ASTM standards. In conclusion, this study highlights the potential of Mahua oil as a valuable and cost-effective feedstock for biodiesel production, thereby opening avenues for its future application as an alternative fuel source.

Enhancing waste cooking oil biodiesel yield and characteristics through machine learning, response surface methodology, and genetic algorithms for optimal utilization in CI engines

ABSTRACT The current study seeks to predict and optimize the biodiesel production yield and physicochemical properties of waste cooking oil. Using Box-Behnken design (BBD), L46 orthogonal arrays were developed for experimentation at five factors and three levels. Furthermore, three different boosting algorithms (AdaBoost, ExtraTrees, and Gradient-Boosting regression) were used to develop an ML-based prognostic model using experimental data. Based on the coefficient of determination (R2) (0.997 for biodiesel yield, 0.999 for kinematic viscosity, 0.996 for calorific value, and 0.999 for flash point), the Gradient-Boosting model has the most accurate predictions, followed by ExtraTrees and AdaBoost. Through the implementation of GA, the most optimal conditions for biodiesel production were obtained, including a molar ratio of 7.24:1, catalyst concentrations of 1.49 wt.%, reaction temperatures of 65°C, reaction times of 59.95 minutes, and stirring speeds of 733.32 rpm. Experimental validation of these optimized conditions is closely aligned with the predicted values. Furthermore, the study evaluates engine performance and emission parameters to assess the impact of different biodiesel/diesel blends (B10, B20, and B30) compared to pure diesel. The utilization of these biodiesel blends demonstrates satisfactory performance, effectively reducing carbon monoxide (CO) and hydrocarbon (HC) emissions. However, nitrogen oxide (NOx) emissions increase compared to pure diesel.

Box–Behnken optimization of biodiesel production using trisodium phosphate catalyst from monazite ore processes

AbstractTrisodium phosphate (TSP) is a non‐toxic waste obtained from alkaline cracking as part of the processing of monazite ore. After simple purification, TSP can be utilized in many applications; however, it is used as a catalyst in this study. It is characterized using Thermogravimetric analysis , X‐ray diffraction analysis, Brunauer‐Emmett‐Teller, and Temperature‐programmed desorption of carbon dioxide and optimized in the transesterification reaction. After recrystallization and calcination at 350 °C for 0.5 h, the form of the TSP was tetragonal, with a 2.61 m2/g surface area and 537.4 x 10‐6 mol/g basic sites. Trisodium phosphate can therefore be utilized effectively as a solid base catalyst for the transesterification of palm oil. Three biodiesel production parameters were investigated: the methanol to oil molar ratio (6:1–24:1), catalyst concentration (1–10%), and reaction time (30 to 240 min). The experiments were designed using the Box–Behnken response surface method. As a result, the optimum conditions for biodiesel production are a 22:1 methanol to oil molar ratio, 4% catalyst concentration, and 200 min reaction time. The optimal fatty acid methyl ester (FAME) content is 99.79%, with an error between actual and predicted FAME of 0.21%. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd.

Ion Exchange Resin and Entrapped Candida rugosa Lipase for Biodiesel Synthesis in the Recirculating Packed-Bed Reactor: A Performance Comparison of Heterogeneous Catalysts

Ion exchange resins and immobilized lipase as heterogeneous catalysts are used to synthesize biodiesel for alternative fossil fuels. The use of ion exchange resins in the solid and activated phase can ease the separation process. Furthermore, resins can be reactivated and used repeatedly, reducing the need for catalysts. On the other hand, an immobilized enzyme is biodegradable and can catalyze the transesterification process to produce biodiesel with a lower alcohol-to-oil ratio, minimizing side reactions and impurities. Therefore, the catalysts used in this study are ion exchange resins, such as Lewatit MP-64, Amberlite IRA410Cl, and Diaion PK208LH, as well as immobilized Candida rugosa lipase. By using vegetable oil as a feedstock and methanol for the transesterification, biodiesel production was carried out in a packed bed reactor. The present study aims to investigate the optimum process parameters, including the concentration of resin and enzyme, resin activation time, resin types, flowrate, and stability of resin and enzyme on the biodiesel yield. The results showed that the optimum conditions for biodiesel production with ion exchange resin were 4 g of resin, activated for 3 h, and synthesized for 3 h; Lewatit obtained a biodiesel yield of 94.06%, Amberlite obtained 90.00%, and Diaion obtained 73.88%. Additionally, the stability test of the reactivated Lewatit resin showed that it still has the capability of producing biodiesel with a yield of more than 80% after three regeneration cycles. In contrast, Candida rugosa lipase as was immobilized by entrapment in sodium alginate before being used in the biodiesel production for 12 h. The results showed that lower flowrate in enzymatic biodiesel synthesis produced a higher amount of biodiesel, of up to 71.1%. Nonetheless, immobilized lipases can be used up to three times without a significant loss in biodiesel yield.

Pre-treatment of waste cooking oil by combined activated carbon adsorption and acid esterification for biodiesel synthesis via two-stage transesterification

The abundance of waste cooking oil (WCO) makes it an attractive alternative for biodiesel production. To date, research emphasizing biodiesel production via two-step transesterification from WCO, with the pre-treatment of WCO using combined activated carbon adsorption and acid esterification, is limited. Therefore, it is the aim of this study to (1) reduce the free fatty acid of WCO through a combination of pre-treatment using activated carbon and esterification of acid catalysis simultaneously, (2) maximize the production of biodiesel via a two-step transesterification process, and (3) compare the converted biodiesel against the biodiesel standards. The amount of activated carbon and the reaction time for each step of the transesterification process are varied. The combination pre-treatment method has successfully reduced the FFA content in WCO from 9.297% to below 3%. The produced biodiesel is verified as fully converted biodiesel via solubility testing in ethanol. The optimum conditions for biodiesel production are pre-treatment using 5 g of powdered activated carbon and a reaction time for each transesterification step of 30 min. The biodiesel generated under these conditions meets the biodiesel standards. It has the highest content of saturated fatty acid, with the maximum biodiesel yield of 52.78%.

Biodiesel yield optimisation from a third-generation feedstock (microalgae spirulina) using a hybrid statistical approach

The current study aims to find the optimum input parameters for high-quality biodiesel synthesis utilising response surface methodology (RSM), a genetic algorithm (GA), and the cuckoo search algorithm (CSA) approach. The L30 pre-designed and executed experiments explored the significance of four process parameters: the methanol to oil molar ratio, catalyst concentration, reaction temperature, reaction time, and their combined effect on biodiesel production. The optimum conditions for biodiesel production were a molar ratio of 7.54:1 (methanol to oil), a KOH catalyst concentration of 0.5 wt. %, a reaction temperature of 65 °C for 102.57 min of reaction time, and a corresponding value of yield of 97.76%. With a correlation coefficient (R2) of 98.23 and a root-mean-squared error (RMSE) of 0.9995, it was seen that RSM gave a robust and consistent model. Microalgae methyl ester fuel characteristics were evaluated and compared to ASTM standards and found acceptable. Thus, the synthesis of high-quality, high-yield biodiesel from microalgae is a feasible alternative.

RSM process optimization of biodiesel production from rapeseed oil and waste corn oil in the presence of green and novel catalyst

In the scenario of global warming and pollution, the green synthesis and use of biodiesel has acquired utmost priority. Due to several limitations of homogeneous catalysis, organobase immobilized heterogeneous catalyzed production of biodiesel has come out as a favored route. The present report demonstrates the design and synthesis of Peganum harmala spice seed extract modified GO-CuFe2O4 (SSE@GO-CuFe2O4) nanocomposite as an organobase functionalized high surface area magnetic nanocatalyst. Pistachio leaves were used in the green reduction of precursor salts to synthesize CuFe2O4 NPs. The as-synthesized nanomaterial was characterized physicochemically by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), elemental mapping, transmission electron microscopy (TEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating sample magnetometer techniques (VSM). Subsequently, the catalyst was explored in the efficient synthesis of biodiesels by trans-esterification of two substrates, the rapeseed oil and waste corn oil. The optimum conditions for biodiesel production were determined through response surface methodology based on Box–Behnken design including the study of calibration curves and 3D contour plots. Easy separation and workup, use of green medium, excellent reused for several times and short reaction time are outstanding benefits of this study.

Synergetic effect of sustainable protic deep eutectic solvent and sonochemical extractor for extractive transesterification of biodiesel from Chlorella salina

Sustainable one-pot biodiesel production by sonochemical extractive transesterification (SET) in Chlorella salina was achieved with protic deep eutectic solvents (pDES). Six pDES were prepared with quaternary ammonium salts as hydrogen bond acceptors and organic acids as hydrogen bond donors. The eutectic mixture formed with choline chloride and lactic acid having moderate density and viscosity yields maximum FAME (90.8 % (w/w)) than the counterparts with higher density. Response surface methodology-based optimization was carried out and 25 % (w/v) of biomass load, 62.5 % (v/v) of DES/methanol ratio, 338 K of ultrasound temperature and 25 min of ultrasound time were identified as optimal conditions for biodiesel production. The resulting biodiesel was found to have an acceptable density (870 g cm−3), viscosity (4.24 mm2/s), acid value (0.31) and iodine index (62 mg/kg biodiesel) as per the EN 14214 standard. Further characterization by FTIR and GC–MS reveals that 90 % of methyl esters have lower carbon chains (<19) resulting in superior quality biodiesel. The activation energy for first order kinetics in the extractive transesterification process was observed as 28.304 KJ/mol. The positive values of Gibb’s free energy and Enthalpy and the negative value of Entropy indicate the process to be non-spontaneous, endothermic and endergonic in nature.

Optimization of the Biodiesel Production via Transesterification Reaction of Palm Oil using Response Surface Methodology (RSM): A Review

The optimization method is vital in chemical synthesis and has been applied in many fields nowadays. Response surface methodology (RSM) is an example of an optimization method that is useful in examining the effects of multiple independent variables. RSM was applied in many studies to optimize the transesterification of biodiesel production from palm oil in the presence of a catalyst. This paper aims to provide an overview of recent catalyzed transesterification trends, as well as the benefits and drawbacks of heterogeneous, homogeneous, and enzyme catalysts in biodiesel production. RSM was used to design the process and statistically analyze the interaction effects of the independent reaction variables. The reaction variables, such as reaction time, reaction temperature, catalyst amount, and the molar ratio of the substrate, were optimized during the process. A statistical model and response surface plots were visualized graphically in the contour plots and three-dimensional figures to explain the interactive effects of variables on a response. In sum, this paper discussed the relationships between the reaction parameters and the production of biodiesel and the optimum conditions for biodiesel production using RSM.

Biodiesel from high‐acid‐value grease trap waste: process optimization and purification using bio‐based adsorbent

AbstractMaterial with negative value such as grease trap waste appears to be a cost‐effective feedstock for biodiesel production since it can be collected at little to no charge. Owing to its high lipid content, fatty acid methyl ester can be produced from grease trap waste via a two‐step production process with methanol, using potassium hydroxide as the catalyst. However, there are several process parameters that could affect the yield of the fatty acid methyl ester produced. In this study, the optimum conditions for biodiesel production were 6:1 methanol‐to‐oil molar ratio, 1.5 wt% potassium hydroxide loadings, a 40 °C reaction temperature and a 2 h reaction time, resulting in a fatty acid methyl ester yield of 87%. Further purification using 0.05 g L−1 of biobased adsorbent from woodchip biomass for a 1 h residence time at 25 °C yielded the highest removal of free fatty acid and soap at 98.2 and 67.9%, respectively. This study not only demonstrates the potential of grease trap waste as a bioresource for the production of biodiesel, but also proves an interesting and additional use of bio‐based adsorbent from woodchip biomass as an effective tool in biodiesel purification since the quality of biodiesel produced within the standard EN14214. © 2022 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Life cycle assessment multi-objective optimization for eco-efficient biodiesel production using waste cooking oil

In recent decades, fossil fuel consumption has increased exponentially despite limited resources, high cost, excessive air pollution and environmental degradation. This has contributed to an increasing recognition of biodiesel as an alternative combustible. This combustible is produced by a process of chemical transesterification. The study investigates modelling and optimal conditions for biodiesel production. It is based on five input process parameters that cause the greater environmental impact when employing used cooking oil. These input parameters are the methanol to oil molar ratio, catalyst dose, reaction temperature, reaction time and stirred speed. Biodiesel yield, high heating value and energy consumption also were considered to be output process variables, whereas global warming, acidification, human toxicity, terrestrial ecotoxicity and fresh water aquatic ecotoxicity were considered to be environmental impacts of the process. The effect on the environment of various input process parameters is often determined by life cycle assessment. Current paper provides a novel optimization of biodiesel production from waste cooking oil using multi-response surface methodology and life cycle assessment. It improves a new optimal sustainability production of biodiesel by combining the input process parameters, while minimizing the environmental impacts of the process. Four different optimization scenarios were proposed. The first scenario is one with a higher yield and higher heating value, but requires less catalyst and a lower methanol to oil molar ratio, as well as the power necessary for the chemical process. The second scenario attempts to minimize the environmental impact of the process on global warming, acidification, human toxicity, terrestrial ecotoxicity and fresh water aquatic ecotoxicity, while minimizing the methanol to oil molar ratio and the catalyst dose. In addition to considering the input process parameters and environmental impacts in the second scenario, the third scenario minimizes the power that the chemical process requires. Finally, the fourth scenario considered the same input process parameters and environmental impact as the third scenario in an effort to minimize the reaction time of the process. This fourth scenario was the one of least environmental impact in the production of biodiesel (global warming = 0.351768 kg CO2 eq.; human toxicity = 0.103402 kg 1.4-BD eq. and fresh water aquatic ecotoxicity = 0.027826 kg 1.4-BD eq.), in an efficient way ((η = 0.91374) while the calorific value of biodiesel obtained was high 42.466742 MJ/kg). The results enabled one to conclude that it is possible to optimize the chemical process in biodiesel production for a high yield and high heating value of that the biofuel, as well as a lower environmental impact.

Comprehensive Optimisation of Biodiesel Production Conditions via Supercritical Methanolysis of Waste Cooking Oil

Biodiesel has been established as a promising alternative fuel to petroleum diesel. This study offers a promising energy conversion platform to valorise high acidity waste cooking oil (WCO) into biodiesel in a single-step reaction via supercritical methanol. Carbon dioxide (CO2) has been used as a co-solvent in the reaction with a catalytic effect to enhance the production of biodiesel. This work provides an in-depth assessment of the yield of four fatty acids methyl esters (FAME) from their correspondent triglycerides and fatty acids. The effects of four independent process variables, i.e., methanol to oil (M:O) molar ratio, temperature, pressure, and time, have been investigated using Response Surface Methodology (RSM). Four quadratic models have been developed between process variables and the yield of FAMEs. The statistical validation of the predicted models has been performed using analysis of variance (ANOVA). Numerical optimisation has been employed to predict the optimal conditions for biodiesel production. The predicted optimal conditions are at 25:1 M:O molar ratio, 254.7 °C, 110 bar within 17 min resulting in 99.2%, 99.3%, 99.13%, and 99.05% of methyl-oleate, methyl-palmitate, methyl-linoleate, and methyl-stearate yields, respectively. The predicted optimum conditions have been validated experimentally.

Preparation of zinc oxide graphted nickel incorporated mesoporous SBA-16 doped graphene oxide: An efficient catalyst for transesterification of waste edible oil to biodiesel and photocatalytic degradation of organic dyes

Graphene-based composite materials a wide range of applications, including the production of electronic components and capacitors, as well as adsorption and catalysis. In this work, the ZnO/Ni-SBA-16@GO nanocatalyst was applied to synthesized biodiesel from waste edible oil (WEO) as an efficient and easily available source. The said nanomaterial was applied for the degradation of methylene blue (MB) and methyl orange (MO). The catalyst was characterized by HRTEM, XRD (small angle and wide angle), SEM, EDX, BET, N2 adsorption/desorption isotherm, and TGA. The findings illustrated that the nanostructure has well-controlled pore diameter (4.0 nm) and prominent surface area (735 m2/g). Furthermore, it was possible to reuse the catalyst up to five times; with the results indicating that the catalyst's catalytic activity was sufficient for the synthesis of WEO biodiesel for up to three cycles before diminishing. The present study used a centralized composite approach to look at the influence of numerous features on biodiesel synthesis in order to discover the optimal conditions for biodiesel production. According to the findings, the maximum biodiesel conversion yields 98% had been obtained during a 7-hour reaction time at a temperature of 70 °C. The nanostructure has also been worked as a photocatalyst to degrade MB and MO. According to the statistics, more than 90% of both dyes were degraded in less than 40 min.

Enhanced biodiesel production from wet microalgae biomass optimized via response surface methodology and artificial neural network

This study investigates modeling and optimal conditions for biodiesel production from exceedingly wet microalgae Chlorella pyrenoidosa using the catalyst, hydrochloric acid. Three levels of Box-Behnken design response surface methodology were used to optimize individual and interactive effects of parameter time (120–240 min), temperature (120–160 °C), solvent-to-wet biomass ratio (2.0–4.67), and hydrochloric acid concentration (2–4 M). Temperature was the most significant factor for direct transesterification of wet microalgae (low p-value (0.0001) and high F-value (53.89). The highest yield (19.90%) of fatty acid methyl ester was obtained on dry biomass weight basis under the optimum conditions of 240 min, 146 °C, 2.83 (vol/wt), and 3.86 M acid concentration. The artificial neural network and response surface methodology were trained with Box-Behnken design data to predict responses, and to develop and compare each model's predictive abilities. The accuracy of results indicates that both models predict the experimental data for fatty acid methyl ester yields with high correlation coefficients (R2) 0.94 and 0.92, respectively for artificial neural network and response surface methodology. The potential for producing biodiesel from C. pyrenoidosa is validated by the high yields of C18 fatty acid methyl esters. Experimental analysis demonstrated biodiesel quality in comparison with European and US standards.

Outstanding activity of a biodiesel coated K2O/fumed silica catalyst in the transesterification reaction

In this study, several KOH loadings (10, 20, and 30 wt %) were impregnated on fumed silica (FS) using the wet impregnation method followed by calcination at 500 °C for 3 h. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. Catalysts were tested in the transesterification of sunflower oil. The catalyst with a 30 wt % loading of KOH (30KOH/FS) showed the best catalytic performance by exhibiting the highest FAME yield. Optimum conditions for biodiesel production over this catalyst were, a reaction time of 4 h at 60 °C, a catalyst to oil ratio of 10 wt % and a methanol to oil molar ratio of 12:1 giving a final FAME yield of 99.9 %. The reusability study revealed a slight deactivation after 3 consecutive runs, attributed to the adsorption of hydrocarbons on the active sites. A breakthrough was achieved when the catalyst was coated with biodiesel (3 wt % with respect to oil in the initial methanol-oil mixture) which formed a protective layer over the active sites. This resulted in a better stability of the 30KOH/FS catalyst as it maintained the maximum FAME yield (99.9 %) over 3 consecutive runs. The properties of the produced biodiesel complied with the ASTM requirements. The coated catalyst also attained and maintained the maximum FAME yield (99.9 %) over 3 consecutive runs in the transesterification of waste cooking oil demonstrating its potential for industrial application.

Improvement of biodiesel production using waste cooking oil and applying single and mixed immobilised lipases on polyhydroxyalkanoate

Abstract This study describes the production of biodiesel via the enzymatic transesterification reaction, using waste cooking oil as a substrate. Lipases from Candida rugosa and Rhizomucor miehei were immobilised on polyhydroxybutyrate to serve as environment-friendly catalysts. This enzyme mixture yielded the highest biodiesel production. The optimum conditions for biodiesel production included a reaction temperature of 45 °C, 5% water content, 1% of mixed lipase (50% of each lipase), a methanol:oil ratio of 6:1, a 24-h reaction period, and a 250 rpm stirring speed, which resulted in the highest biodiesel yields (96.5%). This catalyst can be reused for more than six cycles, after which the lipase activity begins to decrease. The chemical and fuel properties such as the density at 15 °C, viscosity at 40 °C and cloud point of the resulting biodiesel were similar to those of other diesels/biodiesels and complied with international specifications (EN 14214 and ASTM D 6751).