Alkaline-catalyzed transesterification of Silurus triostegus Heckel fish oil: Optimization of transesterification parameters

The present work reports the production of biodiesel from Silurus triostegus Heckel fish oil (STFO) through alkaline-catalyzed transesterification by using potassium hydroxide (KOH) as an alkaline catalyst with methanol. Chemical and physical properties of the extracted oil were determined. It was found that STFO has a low acid value (1.90 mg KOH/g oil); hence no pre-treatment such as acid esterification is required to produce the biodiesel. The influence of the experimental parameters such as KOH concentration (0.25–1.0% w/w of oil), methanol to oil molar ratio (3:1, 6:1, 9:1 and 12:1), reaction temperature (32, 45 and 60 °C), reaction duration (30, 60, 90 and 120 min), type of the catalyst (potassium or sodium hydroxide) and step multiplicity (single- and two-step transesterification) on the yield of the biodiesel were investigated. The maximum biodiesel yield (96%) was obtained under the optimized parameters of the transesterification (KOH 0.50% w/w, 6:1 methanol to oil, at 32 °C for 60 min). The properties of the produced biodiesel were found to conform with the ASTM standard, indicating its suitability for internal combustion engines. Blending of the produced biodiesel with petro diesel with various volume percentages was investigated as well.     

A comparative study of KOH/Al2O3 and KOH/NaY catalysts for biodiesel production via transesterification from palm oil

The transesterification of palm oil to methyl esters (biodiesel) was studied using KOH loaded on Al₂O₃ and NaY zeolite supports as heterogeneous catalysts. Reaction parameters such as reaction time, wt% KOH loading, molar ratio of oil to methanol, and amount of catalyst were optimized for the production of biodiesel. The 25 wt% KOH/Al₂O₃ and 10 wt% KOH/NaY catalysts are suggested here to be the best formula due to their biodiesel yield of 91.07% at temperatures below 70 °C within 2–3 h at a 1:15 molar ratio of palm oil to methanol and a catalyst amount of 3–6 wt%. The leaching of potassium species in both spent catalysts was observed. The amount of leached potassium species of the KOH/Al₂O₃ was somewhat higher compared to that of the KOH/NaY catalyst. The prepared catalysts were characterized by using several techniques such as XRD, BET, TPD, and XRF.     

Optimisation of base-catalysed transesterification of Simarouba glauca oil for biodiesel production

Biodiesel was prepared from the crude oil of Simarouba glauca by transesterification with methanol in the presence of KOH as a catalyst. The reaction parameters such as catalyst concentration, alcohol to oil molar ratio, temperature and rate of mixing were optimised for the production of Simarouba oil methyl ester. The yield of methyl esters from Simarouba oil under the optimal condition was 94–95%. Important fuel properties of methyl esters of Simarouba oil (biodiesel) was compared with ASTM and DIN EN 14214. The viscosity was found to be 4.68 Cst at 40°C and the flashpoint was 165°C.     

Preparation, characterization and application of heterogeneous solid base catalyst for biodiesel production from soybean oil

A solid base catalyst was prepared by neodymium oxide loaded with potassium hydroxide and investigated for transesterification of soybean oil with methanol to biodiesel. After loading KOH of 30 wt.% on neodymium oxide followed by calcination at 600 °C, the catalyst gave the highest basicity and the best catalytic activity for this reaction. The obtained catalyst was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), N₂ adsorption-desorption measurements and the Hammett indicator method. The catalyst has longer lifetime and maintained sustained activity after being used for five times, and were noncorrosive and environmentally benign. The separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and reaction time were investigated. The experimental results showed that a 14:1 M ratio of methanol to oil, addition of 6.0% catalyst, 60 °C reaction temperature and 1.5 h reaction time gave the best results and the biodiesel yield of 92.41% was achieved. The properties of obtained biodiesel are close to commercial diesel fuel and is rated as a realistic fuel as an alternative to diesel.     

Biodiesel production from refined sunflower vegetable oil over KOH/ZSM5 catalysts

ZSM5 zeolite was impregnated with different KOH loadings (15 wt.%, 25 wt.% and 35 wt.%) to prepare a series of KOH/ZSM5 catalysts. The catalysts were calcined at 500 °C for 3 h and then characterized by N₂ adsorption–desorption and X-ray diffraction (XRD) techniques. The catalysts were tested in the transesterification reaction in a batch reactor at 60 °C and under atmospheric pressure. It was found that KOH/ZSM5 with 35 wt.% loading showed the best catalytic performance. The best reaction conditions in the presence of KOH/ZSM5 (35 wt.%) were determined while modifying the catalyst to oil ratio and the reaction time. The highest methyl ester yield (>95%) was obtained for a reaction time of 24 h, a catalyst to oil ratio of 18 wt.%, and a methanol to oil molar ratio of 12:1. The properties of produced biodiesel complied with the ASTM specifications. The catalytic stability test showed that 35KOH/ZSM5 was stable for 3 consecutive runs. Characterization of the spent catalyst indicated that a slight deactivation might be due to the leaching of potassium oxides active sites.     

Application of response surface methodology for optimizing transesterification of Moringa oleifera oil: Biodiesel production

Response surface methodology (RSM), with central composite rotatable design (CCRD), was used to explore optimum conditions for the transesterification of Moringa oleifera oil. Effects of four variables, reaction temperature (25–65 °C), reaction time (20–90 min), methanol/oil molar ratio (3:1–12:1) and catalyst concentration (0.25–1.25 wt.% KOH) were appraised. The quadratic term of methanol/oil molar ratio, catalyst concentration and reaction time while the interaction terms of methanol/oil molar ratio with reaction temperature and catalyst concentration, reaction time with catalyst concentration exhibited significant effects on the yield of Moringa oil methyl esters (MOMEs)/biodiesel, p < 0.0001 and p < 0.05, respectively. Transesterification under the optimum conditions ascertained presently by RSM: 6.4:1 methanol/oil molar ratio, 0.80% catalyst concentration, 55 °C reaction temperature and 71.08 min reaction time offered 94.30% MOMEs yield. The observed and predicted values of MOMEs yield showed a linear relationship. GLC analysis of MOMEs revealed oleic acid methyl ester, with contribution of 73.22%, as the principal component. Other methyl esters detected were of palmitic, stearic, behenic and arachidic acids. Thermal stability of MOMEs produced was evaluated by thermogravimetric curve. The fuel properties such as density, kinematic viscosity, lubricity, oxidative stability, higher heating value, cetane number and cloud point etc., of MOMEs were found to be within the ASTM D6751 and EN 14214 biodiesel standards.     

Performance evaluation of artificial neural network coupled with generic algorithm and response surface methodology in modeling and optimization of biodiesel production process parameters from shea tree (Vitellaria paradoxa) nut butter

This work investigated the potential of shea butter oil (SBO) as feedstock for synthesis of biodiesel. Due to high free fatty acid (FFA) of SBO used, response surface methodology (RSM) was employed to model and optimize the pretreatment step while its conversion to biodiesel was modeled and optimized using RSM and artificial neural network (ANN). The acid value of the SBO was reduced to 1.19 mg KOH/g with oil/methanol molar ratio of 3.3, H₂SO₄ of 0.15 v/v, time of 60 min and temperature of 45 °C. Optimum values predicted for the transesterification reaction by RSM were temperature of 90 °C, KOH of 0.6 w/v, oil/methanol molar ratio of 3.5, and time of 30 min with actual shea butter oil biodiesel (SBOB) yield of 99.65% (w/w). ANN combined with generic algorithm gave the optimal condition as temperature of 82 °C, KOH of 0.40 w/v, oil/methanol molar ratio of 2.62 and time of 30 min with actual SBOB yield of 99.94% (w/w). Coefficient of determination (R²) and absolute average deviation (AAD) of the models were 0.9923, 0.83% (RSM) and 0.9991, 0.15% (ANN), which demonstrated that ANN model was more efficient than RSM model. Properties of SBOB produced were within biodiesel standard specifications.     

Manufacturing of zeolite based catalyst from zeolite tuft for biodiesel production from waste sunflower oil

In the present work, zeolite based catalyst was prepared from zeolite tuft by impregnation methods. The zeolite tuft was initially treated with hydrochloric acid (16%) and then several KOH/zeolite catalysts were prepared by impregnation in KOH solutions. Various solutions of KOH with different molarities (1–6 M) were used. Further modification for the catalyst was performed by a 2nd step impregnation treatment by heating and stirring the KOH/zeolite to 80 °C for 4 h. The zeolite tuft and the prepared catalysts were characterized by several analytical techniques in order to explore their physicochemical properties. These tests include: X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), Zero point of Charge (PHzpc), Fourier Transform Infrared (FT-IR), Energy-dispersive X-Ray analysis (EDX) and X-Ray Diffraction (XRD). The catalysts were then used for transesterification of waste sunflower vegetable oil in order to produce biodiesel. Among the different catalysts prepared, the 1–4M KOH/TZT catalyst provided the maximum biodiesel yield of 96.7% at 50 °C reaction temperature, methanol to oil molar ratio of 11.5:1, agitation speed of 800 rpm, 335 μm catalyst particle size and 2 h reaction time. The physicochemical properties of the produced biodiesel comply with the EN and ASTM standard specifications.     

Optimization of biodiesel production from waste fish oil

The present study deals with the production of biodiesel using waste fish oil. The research assesses the effect of the transesterification parameters on the biodiesel yield and its properties, including temperature (40–60 °C), molar ratio methanol to oil (3:1–9:1) and reaction time (30–90 min). The experimental results were fitted to complete quadratic models and optimized by response surface methodology. All the biodiesel samples presented a FAME content higher than 93 wt.% with a maximum, 95.39 wt.%, at 60 °C, 9:1 of methanol to oil ratio and 90 min. On the other hand, a maximum biodiesel yield was found at the same methanol to oil ratio and reaction time conditions but at lower temperature, 40 °C, which reduced the saponification of triglycerides by the alkaline catalyst employed. Adequate values of kinematic viscosity (measured at 30 °C) were obtained, with a minimum of 6.30 mm²/s obtained at 60 °C, 5.15:1 of methanol to oil ratio and 55.52 min. However, the oxidative stability of the biodiesels produced must be further improved by adding antioxidants because low values of IP, below 2.22 h, were obtained. Finally, satisfactory values of completion of melt onset temperature, ranging from 3.31 °C to 3.83 °C, were measured.     

Analysis and evaluation of operating variables for the yield of Karanja and neem oil-based biodiesel production

The aim of this research is to present the possibilities of the use of non-edible oils in biodiesel production, to consider the various methods for treatment of non-edible oils and to emphasise the influence of the operating and reaction conditions on the process rate and the ester yield. Because of biodegradability and non-toxicity biodiesel has become more attractive as alternative fuel. Biodiesel is produced mainly from vegetable oils by transesterification. For economic and social reasons, edible oils should be replaced by lower-cost and reliable feedstock for biodiesel production, such as non-edible plant oils. In this work biodiesel is produced from neem and Karanja by using butanol, propanol, ethanol and methanol as alcohols and KOH and NaOH as alkali catalysts by the transesterification process. The aim of this research is to analyse the different reaction parameters such as catalyst concentration, type of catalyst, types of alcohol, alcohol to oil molar ratio, reaction time and reaction temperature on the yield of biodiesel from non-edible oils. The maximum yield obtained was 95% with Karanja as oil with methanol and KOH as alkali catalyst at oil to alcohol molar ratio of 6:1 in 1 h at 60°C. Special attention is paid to the possibilities of producing biodiesel from non-edible oils.     

A bronsted basic ionic liquid as an efficient and environmentally benign catalyst for biodiesel synthesis from soybean oil and methanol

Morpholine basic ionic liquid was synthesized with N-methyl morpholine, N-butyl bromide, and KOH by two-step method and was used to catalyze the transesterification of soybean oil with methanol to biodiesel. The structure of the catalyst were examined by ¹H nuclear magnetic resonance. The effects of the molar ratio of methanol to oil, reaction temperature, and amount of catalyst on the biodiesel yield were investigated. Optimized biodiesel yield of 94.5% was achieved with catalyst amount of 3.0 wt%, and methanol to soybean oil molar ratio of 14:1 at reaction temperature of 60 °C for 6 h. The catalyst has maintained sustained activity after being employed to six cycles. The prepared biodiesel component was analyzed by gas chromatography-mass spectrometry (GC-MS) and the results showed that the biodiesel comprised of hexadecanoic acid methyl ester, 10, 13-octadecadienoic acid methyl ester, 9-octadecenoic acid methyl ester, and octadecanoic acid methyl ester, illustrating that fatty acids of soybean oil were converted completely.     

Mixed and ground KBr-impregnated calcined snail shell and kaolin as solid base catalysts for biodiesel production

Mixed and ground activated snail shell and kaolin catalysts impregnated with KBr were investigated. The snail shell and kaolin were calcined, mixed, and ground prior to immersion with KBr solution and subsequent activation at 500 °C for 3 h. The precursor and catalysts were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller surface area. The catalytic performance of the prepared catalysts was evaluated by transesterification of soybean oil with methanol. The effects of various parameters on biodiesel yield were investigated. A biodiesel yield of 98.5% was achieved using the catalyst prepared by 40% KBr-immersed, mixed, and ground snail shell and kaolin, which were activated at 500 °C. The transesterification conditions were as follows: reaction temperature, 65 °C; reaction time, 2 h; methanol-to-soybean oil molar ratio, 6:1; and catalyst amount (relative to the weight of soybean oil), 2.0 wt%. The solid catalyst could be reused for four times, and biodiesel yield remained over 73.6% for the fourth time.     

Production of biodiesel from castor oil using iron (II) doped zinc oxide nanocatalyst

The depletion of fossil fuels has caused the price of petroleum to rise remarkably and created need for alternative energy such as biodiesel. In the present study, the biodiesel was produced from castor oil using ferromagnetic zinc oxide nanocomposite as heterogeneous catalyst for transesterification reaction. Single phase of nanocatalyst were confirmed by X-Ray Diffraction analysis. The spherical shape of the aggregated nanocatalyst was observed in Scanning Electron Microscopy. Magnetic properties were analysed using vibrating sample magnetometer. Atomic Force Microscopic analysis revealed the larger surface area and roughness of nanocatalyst. The biodiesel yield of 91% (w/w) was obtained in 50 min at 55 °C with 14 wt % catalyst loading and 12:1 methanol/oil ratio and was confirmed by Gas chromatograph with Mass Spectrometer. The result showed that the iron (II) doped ZnO nanocatalyst is a promising catalyst for the production of biodiesel via heterogeneous catalytic transesterification under milder reaction conditions.     

Waste capiz (Amusium cristatum) shell as a new heterogeneous catalyst for biodiesel production

The waste Capiz shell was utilized as raw material for catalyst production for biodiesel preparation. During calcination process, the calcium carbonate content in the waste capiz shell was converted to CaO. This calcium oxide was used as catalyst for transesterification reaction between palm oil and methanol to produce biodiesel. The biodiesel preparation was conducted under the following conditions: the mole ration between methanol and palm oil was 8:1, stirring speed was 700 rpm, and reaction temperature was 60 °C for 4, 5, and 6 h reaction time. The amount of catalyst was varied at 1, 2, 3, 4, and 5 wt %. The maximum yield of biodiesel was 93 ± 2.2%, obtained at 6 h of reaction time and 3 wt % of amount of catalyst. In order to examine the reusability of catalyst developed from waste of capiz (Amusium cristatum) shell, three transesterification reaction cycles were also performed.     

Development of novel Ag/bauxite nanocomposite as a heterogeneous catalyst for biodiesel production

Ag/bauxite nanocomposites have been prepared using in situ reduction of aqueous AgNO₃ solution in a bauxite matrix and investigated for the transesterification of sunflower oil with methanol in order to study their potential as heterogeneous catalysts. The prepared nanocopmosites were characterized by XRD, SEM, EDX, FT-IR, and TG- DTA. The Central Composite Design of the Response Surface Methodology was used to optimize the effect of reaction temperature, reaction time, catalyst loading and methanol to oil molar ratio on the yield of fatty acid methyl esters. The highest yield was obtained at 67 °C reaction temperature, 3 h reaction time, 0.3 wt.% catalyst loading and 9:1 methanol to oil molar ratio. Under the optimal conditions, the methyl ester content was 94% and the catalyst successfully reused for at least 7 cycles without significant deactivation.     

Optimization of heterogeneous biodiesel production from waste cooking palm oil via response surface methodology

Heterogeneous transesterification of waste cooking palm oil (WCPO) to biodiesel over Sr/ZrO₂ catalyst and the optimization of the process have been investigated. Response surface methodology (RSM) was employed to study the relationships of methanol to oil molar ratio, catalyst loading, reaction time, and reaction temperature on methyl ester yield and free fatty acid conversion. The experiments were designed using central composite by applying 2⁴ full factorial designs with two centre points. Transesterification of WCPO produced 79.7% maximum methyl ester yield at the optimum methanol to oil molar ratio = 29:1, catalyst loading = 2.7 wt%, reaction time = 87 min and reaction temperature = 115.5 °C.     

Biodiesel from mutton fat using KOH impregnated MgO as heterogeneous catalysts

The use of MgO impregnated with KOH as heterogeneous catalysts for the transesterification of mutton fat with methanol has been evaluated. The mutton fat (fat) with methanol (1:22 M ratio) at 65 °C showed > 98% conversion to biodiesel with 4 wt% of MgO–KOH-20¹ (MgO impregnated with 20 wt% of KOH) in 20 min. The reaction conditions optimized were; the amount of KOH impregnation (5–20 wt%), the amount of catalyst (1.5–4 wt%, catalyst/fat), the reaction temperature (45–65 °C), fat to methanol molar ratio (1:11–1:22) and the effect of addition of water/oleic acid/palmitic acid (upto 1 wt%). Although, transesterification of fresh fat (moisture content 0.02 wt% and free fatty acids 0.002 wt%) with methanol in the presence of KOH (homogenous catalyst) resulted in the complete conversion to biodiesel, but in the presence of additional 1 wt% of either free fatty acid or moisture content, formation of soap was observed. The MgO–KOH-20 catalyst was found to tolerate additional 1 wt% of either the moisture or FFAs in the fat.     

Biodiesel from low cost feedstocks: The effects of process parameters on the biodiesel yield

Biofuel (e.g. biodiesel) has attracted increasing attention worldwide as blending component or direct replacement for fossil fuel in fuel energized engines. The substitution of petroleum-based diesel with biodiesel has already attained commercial value in many of the developed countries around the world. However, the use of biodiesel has not expanded in developing countries mostly due to the high production cost which is associated with the expensive high-quality virgin oil feedstocks. This research focuses on producing of biodiesel from low cost feedstocks such as used cooking oil (UCO) and animal fat (AF) via alkaline catalyzed transesterification process investigating the effects of process parameters, for example (i) molar ratio of feedstock to methanol (ii) catalyst concentration (iii) reaction temperature and (iv) reaction period on the biodiesel yield. The biodiesel was successfully produced via transesterification process from low cost feedstocks. It was also observed that the process parameters directly influenced the biodiesel yield. The optimum parameters for maximum biodiesel yields were found to be methanol/oil molar ratio of 6:1, catalyst concentration of 1.25 wt% of oil, reaction temperature of 65 °C, reaction period of 2 h and stirring speed of 150 rpm. The maximum biodiesel yields at the optimum conditions were 87.4%, 89% and 88.3% for beef fat, chicken fat and UCO, respectively. The results demonstrate high potential of producing economically viable biodiesel from low cost feedstocks with proper optimization of the process parameters.     

A comparative study of vegetable oil methyl esters (biodiesels)

In the present study, rubber seed oil, coconut oil and palm kernel oil, which are locally available especially in Kerala (India), are chosen and their transesterification processes have been investigated. The various process variables like temperature, catalyst concentration, amount of methanol and reaction time were optimized. Biodiesel from rubber seed oil (with high free fatty acid) was produced by employing two-step pretreatment process (acid esterification) to reduce acid value from 48 to 1.72 mg KOH/g with 0.40 and 0.35 v/v methanol-oil ratio and 1.0% v/v H₂SO₄ as catalyst at a temperature of 63(±2) °C with 1 h reaction time followed by transesterification using methanol-oil ratio of 0.30 v/v, 0.5 w/v KOH as alkaline catalyst at 55(±2) °C with 40 min reaction time to yield 98-99% biodiesel. Coconut oil and palm oil, being edible oils, transesterification with 0.25 v/v methanol-oil ratio, 0.50% w/v KOH as at 58(±2) °C, 20 min reaction time for coconut oil and 0.25% v/v methanol-oil ratio, 0.50% w/v KOH as alkaline catalyst at 60(±2) °C for palm kernel oil will convert them to 98-99% biodiesel. The brake thermal efficiency of palm oil biodiesel was higher with lower brake specific fuel consumption, but rubber seed oil biodiesel(ROB) showed less emission (CO and NO_x) compared to other biodiesels.     

Biodiesel production from Calophyllum inophyllum oil using lipase producing Rhizopus oryzae cells immobilized within reticulated foams

Biodiesel production from non-edible Calophyllum inophyllum linn oil with high levels of Free Fatty Acid (FFA) (acid value −6.732 mg KOH/g of oil) was investigated using whole-cell biocatalysts. Rhizopus oryzae cells immobilized within reticulated polyurethane foams were used as biocatalysts for biodiesel production. The effects of reaction parameters such as methanol-to-oil molar ratio, water content, and temperature for the production of biodiesel through methanolysis in a packed-bed reactor (PBR) were studied. Molar ratio of methanol-to-oil – 12:1, water content – 15%v/v, cell concentration – 20% and temperature 35 °C were found to be the optimum. The yield of biodiesel obtained in batch methanolysis from C. inophyllum oil under optimized condition was 92%. Long-term stability of immobilized cells for methanolysis was verified using re-usability studies.