Microbial biodiesel production from industrial organic wastes by oleaginous microorganisms: Current status and prospects

This review aims to encourage the technical development of microbial biodiesel production from industrial-organic-wastes-derived volatile fatty acids (VFAs). To this end, this article summarizes the current status of several key technical steps during microbial biodiesel production, including (1) acidogenic fermentation of bio-wastes for VFA collection, (2) lipid accumulation in oleaginous microorganisms, (3) microbial lipid extraction, (4) transesterification of microbial lipids into crude biodiesel, and (5) crude biodiesel purification. The emerging membrane-based bioprocesses such as electrodialysis, forward osmosis and membrane distillation, are promising approaches as they could help tackle technical challenges related to the separation and recovery of VFAs from the fermentation broth. The genetic engineering and metabolic engineering approaches could be applied to design microbial species with higher lipid productivity and rapid growth rate for enhanced fatty acids synthesis. The enhanced in situ transesterification technologies aided by microwave, ultrasound and supercritical solvents are also recommended for future research. Technical limitations and cost-effectiveness of microbial biodiesel production from bio-wastes are also discussed, in regard to its potential industrial development. Based on the overview on microbial biodiesel technologies, an integrated biodiesel production line incorporating all the critical technical steps is proposed for unified management and continuous optimization for highly efficient biodiesel production.

Two new nucleoside derivatives isolated from the marine-derived Aspergillus versicolor and their intramolecular transesterification

Two new nucleoside derivatives, kipukasins M (1a) and N (1b), along with one known analogue, kipukasin J (2), were obtained from the marine-derived fungus Aspergillus versicolor, which was isolated from the mud collected in the South China Sea. The structures of compounds 1a and 1b were elucidated by extensive spectroscopic analysis, mainly including 1D & 2D NMR and HRESIMS data, and the absolute configuration of 1a was further confirmed by single-crystal X-ray diffraction analysis. Interestingly, intramolecular transesterification occurs in compounds 1a and 1b, which exist as a pair of inseparable regioisomers. All isolated compounds were tested for the cytotoxic and antimicrobial activities.

Biodiesel synthesis from swine manure

This study demonstrates that the biodiesel (BD) from swine manure (SM) could be a promising way for large scale generation of biofuel. Also, the economic and environmental benefits of SM derived BD were evaluated. Transesterification of lipid contents extracted from the collected SM had low BD yield (14.2 wt%) using H₂SO₄ catalyst due to high acid value and impurities. However, thermo-chemical non-catalytic transesterification with a porous material showed 94.7 wt% yield of BD from the lipid in SM. Considering the current population of swine, the annual production of BD from SM was estimated. The SM derived BD could cover 19.7 and 46.8 wt% of BD currently produced in both Korea and the USA with the economic benefits of up to $96 million and $2.1 billion, respectively. The proposed approach also can save vast arable lands needed to cultivate oil-bearing feedstocks for BD production.

Pristine and modified chitosan as solid catalysts for catalysis and biodiesel production: A minireview

Chitosan is one of the readily available polymers with relatively high abundance, biodegradable and sustainable materials with divergent functional groups that are employed in broad range of applications. Chitosan is widely used in many fields like adsorption, drug carrier for therapeutic activity, environmental remediation, drug formulation and among others. One of the unique features of chitosan is that it can be transformed to other forms like beads, films, flakes, sponges and fibres depending upon the applications. This review is aimed at showing the potential applications of chitosan and its modified solids in organic transformations. The number of existing articles is organized based on the nature of materials and subsequently with the types of reactions. After a brief description on the structural features of chitosan, properties, characterization methods including various analytical/microscopic techniques and some of the best practices to be followed in catalysis are also discussed. The next section of this review describes the catalytic activity of native chitosan without any modifications while the subsequent sections provide the catalytic activity of chitosan derivatives, chitosan covalently modified with metal complexes/salts through linkers and chitosan as support for metal nanoparticles (NPs). These sections discuss number of organic reactions that include Knoevenagel condensation, oxidation, reduction, heterocycles synthesis, cross-coupling reactions and pollutant degradation among others. A separate section provides the catalytic applications of chitosan and its modified forms for the production of fatty acid methyl esters (FAME) through esterification/transesterification reactions. The final section summarizes our views on the future directions of this field in the coming years.

Valorization of swine manure biochar as a catalyst for transesterifying waste cooking oil into biodiesel

As demand of proteins from meats has significantly increased with economy growth, the population of livestock proliferates. Thus, heavy amount of livestock byproducts released from livestock industries will become more problematic if they are handled in an unsatisfactory manner. In this study, swine manure (SM) waste was directly valorized to be used as a reaction catalyst for biodiesel production. Pyrolysis was adapted to produce swine manure biochars at 500 (SMB@500) and 650 °C (SMB@650), and the materials were used for conversion of waste cooking oil into biodiesels (i.e., fatty acid methyl esters: FAMEs). The properties of SMBs and resulting pyrolytic gases (i.e., H₂, CO, and C_1-2 hydrocarbons (HCs)) and liquids during pyrolysis were also characterized. SMBs used in this study included a large quantity of metallic contents that significantly contributed to the rapid reaction for biodiesel production. In detail, SMB@500 and SMB@650 showed higher than 96% of FAME yield at 305 and 210 °C of reaction temperature, while non-catalytic reaction using SiO₂ showed similar FAME yield at 330 °C. Thus, this work offers a sustainable way to recycle organic and inorganic materials in livestock manures for energy (biodiesel, pyrolytic oil, H₂, and C_1-2 HCs) production.

A rapid and highly sensitive UPLC-ESI-MS/MS method for the analysis of the fatty acid profile of edible vegetable oils

The analysis of the fatty acid profile of triglycerides has long played a central role in the evaluation and classification of edible vegetable oils. However, the range of analytical procedures available to evaluate these profiles remains limited and are typically based on transesterification of the triglyceride fatty acid residues to methyl esters, followed by capillary gas-liquid chromatography (GC) coupled with flame ionization or mass spectrometry detection. Although robust and long-proven, these analytical methods tend to entail long chromatographic runs and are relatively insensitive. In order to expand the range of available techniques for the analysis of the fatty acid profile of triglycerides in vegetable oils, we report herein a novel method based upon a rapid and straightforward transesterification of the triglycerides with dimethylaminoethanol under alkaline conditions, followed by a "dilute-and-shoot" analysis by ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry. The chromatographic analysis is accomplished in 1.5 min, affording a high throughput of samples compared to techniques based upon GC approaches. The method performance was assessed intra- and inter-day with 10 representative saturated and unsaturated fatty acids ranging from C₈ to C₁₈ and afforded fatty acid profile accuracies of 93-108% and imprecisions of only 0.3-2.0%. The limit of quantification of the method, estimated as the minimum amount of derivatized oil sample capable of affording less than 20% accuracy and precision error was determined to be approximately 0.5 pg on-column, making this new method potentially valuable for fields where high sensitivity, precision, and accuracy may be required, such as in toxicology studies, forensics, archeology, or art analysis.

Synthesis of propyl benzoate by solvent-free immobilized lipase-catalyzed transesterification: Optimization and kinetic modeling

The present study aimed to analyze reaction kinetics and mechanism for the synthesis of propyl benzoate in solvent-free conditions. Lipase was immobilized on Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) polymer blend by entrapment method. Among different lipases immobilized on a support, Candida cylindracea (CCL) showed excellent activity. Systematic studies were done to optimize the reaction conditions. The activation energy was found to be 16.2 kcal/mol for immobilized CCL. Kinetic parameters were calculated, which depicted that propyl benzoate synthesized using immobilized CCL followed the ternary complex model in which propanol inhibits lipase activity at higher concentrations. Recyclability of the catalyst was checked up to four catalytic cycles and 40% retention of activity was observed up to the fourth cycle. Finally, the applicability of developed protocol to synthesize various alkyl benzoates was explored.

Controlling reaction selectivity for sugar fatty acid ester synthesis by using resins with different basicities

A strongly basic ion-exchange resin catalyst was reported to exhibit a high catalytic activity in transesterification to produce a bio-based surfactant, sugar ester under mild condition. However, the side-reactions to decompose the reactant and the product were found to occur. This study was aimed to improve the selectivity of sugar ester synthesis by newly focusing on the basicity of the resin. A weakly basic resin (Diaion WA20) with a lower mass transfer resistance suppressed the decompositions while maintaining synthesis rate. Controlling molar ratio of the reactants in the intraparticle reaction field also increased the reaction selectivity, 72.1% and product yield, 57.5%. Both values were drastically increased compared to the reported values with the strongly basic resin (selectivity 50.9%, yield 14.3%). This is the first knowledge to show a high catalytic activity of weakly basic resin. These results suggest that a more efficient continuous production process would be possible.

Screening of seaweeds for sustainable biofuel recovery through sequential biodiesel and bioethanol production

The present study evaluated the sequential biodiesel-bioethanol production from seaweeds. A total of 22 macroalgal species were collected at different seasons and screened based on lipid and carbohydrate contents as well as biomass production. The promising species was selected, based on the relative increase in energy compounds (REEC, %), for further energy conversion. Seasonal and annual biomass yields of the studied species showed significant variations. The rhodophyte Amphiroa compressa and the chlorophyte Ulva intestinalis showed the highest annual biomass yield of 75.2 and 61.5 g m^-2 year^-1, respectively. However, the highest annual carbohydrate productivity (ACP) and annual lipid productivity (ALP) were recorded for Ulva fasciata and Ulva intestinalis (17.0 and 3.0 g m^-2 year^-1, respectively). The later was selected for further studies because it showed 14.8% higher REEC value than Ulva fasciata. Saturated fatty acids (SAFs) showed 73.4%, with palmitic acid as a dominant fatty acid (43.8%). Therefore, biodiesel showed high saturation degree, with average degree of unsaturation (ADU) of 0.508. All the measured biodiesel characteristics complied the international standards. The first route of biodiesel production (R1) from Ulva intestinalis showed biodiesel recovery of 32.3 mg g^-1 dw. The hydrolysate obtained after saccharification of the whole biomass (R2) and lipid-free biomass (R3) contained 1.22 and 1.15 g L^-1, respectively, reducing sugars. However, bioethanol yield from R3 was 0.081 g g^-1 dw, which represented 14.1% higher than that of R2. Therefore, application of sequential biofuel production using R3 resulted in gross energy output of 3.44 GJ ton^-1 dw, which was 170.9% and 82.0% higher than R1 and R2, respectively. The present study recommended the naturally-grown Ulva intestinalis as a potential feedstock for enhanced energy recovery through sequential biodiesel-bioethanol production.

Pineapple (Ananás comosus) leaves ash as a solid base catalyst for biodiesel synthesis

Homogeneous catalysts used for biodiesel synthesis have several limitations, including non-recoverability/reusability, saponification, emulsification, equipment corrosion, and environmental pollution. To overcome these limitations, we synthesized a novel catalyst via calcination of pineapple leaves waste. This catalyst was characterized by X-ray powder diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and soluble alkalinity measurements. The catalyst's activity with regards to soybean oil transesterification was analyzed, and multiple process parameters (temperature, catalyst amount, reaction time, and methanol:oil molar ratio) were examined. A high catalytic activity, probably related to the 85 wt% content of alkali/alkali metals (K, Ca and Mg), was observed after a 30 min reaction time, 60 °C, 4 wt% of catalyst, oil to methanol molar ratio of 1:40, reaching an oil to biodiesel conversion above 98%. We conclude that the novel catalyst presented here is efficient, cost-effective, and sustainable, while simultaneously abundant waste is reduced.

Magnetic responsive Thermomyces lanuginosus lipase for biodiesel synthesis

The low cost lipase derived from Thermomyces lanugionous was chosen to conjugate with Fe₃O₄ nanoparitcles as a magnetic responsive lipase (MRL) biocatalyst. The structure of MRL was observed by atomic force microscopy (AFM). The Fourier transform infrared (FTIR) spectroscopy analysis confirmed the lipase conjugated to Fe₃O₄ nanoparticles. Optimized conditions for the process of biodiesel production by MRL were investigated by the response surface methodology (RSM) and the Box-Behnken design (BBD). The optimized conditions for biodiesel production by MRL were as follows. The molar ratio of methanol to oil was 4.0, water content was 1.5 % as oil weight, the dosage of MRL to oil was 9.0 % (W/W) under 41 °C for 28 h. Under the optimized conditions, the yield of FAMEs by MRL reached 82.20 %. Further experiments showed that the MRL could be used 10 cycles and the yield of FAMEs decreased slightly by 10.97 %. These results indicated that Fe₃O₄ nanoparticle carrier could efficiently improve the FAMEs synthesis and enhance the MRL stabilization and reusability in the biodiesel production.

Screening of seaweeds for sustainable biofuel recovery through sequential biodiesel and bioethanol production

The present study evaluated the sequential biodiesel-bioethanol production from seaweeds. A total of 22 macroalgal species were collected at different seasons and screened based on lipid and carbohydrate contents as well as biomass production. The promising species was selected, based on the relative increase in energy compounds (REEC, %), for further energy conversion. Seasonal and annual biomass yields of the studied species showed significant variations. The rhodophyte Amphiroa compressa and the chlorophyte Ulva intestinalis showed the highest annual biomass yield of 75.2 and 61.5 g m^-2 year^-1, respectively. However, the highest annual carbohydrate productivity (ACP) and annual lipid productivity (ALP) were recorded for Ulva fasciata and Ulva intestinalis (17.0 and 3.0 g m^-2 year^-1, respectively). The later was selected for further studies because it showed 14.8% higher REEC value than Ulva fasciata. Saturated fatty acids (SAFs) showed 73.4%, with palmitic acid as a dominant fatty acid (43.8%). Therefore, biodiesel showed high saturation degree, with average degree of unsaturation (ADU) of 0.508. All the measured biodiesel characteristics complied the international standards. The first route of biodiesel production (R1) from Ulva intestinalis showed biodiesel recovery of 32.3 mg g^-1 dw. The hydrolysate obtained after saccharification of the whole biomass (R2) and lipid-free biomass (R3) contained 1.22 and 1.15 g L^-1, respectively, reducing sugars. However, bioethanol yield from R3 was 0.081 g g^-1 dw, which represented 14.1% higher than that of R2. Therefore, application of sequential biofuel production using R3 resulted in gross energy output of 3.44 GJ ton^-1 dw, which was 170.9% and 82.0% higher than R1 and R2, respectively. The present study recommended the naturally-grown Ulva intestinalis as a potential feedstock for enhanced energy recovery through sequential biodiesel-bioethanol production.

Multilayered Nano-Entrapment of Lipase through Organic-Inorganic Hybrid Formation and the Application in Cost-Effective Biodiesel Production

Significant components of cost-effective medium for Magnusiomyces capitatus A4C extracellular lipase (ECL) production were optimized via a five-level factorial design. A simplistic, economical, and green approach was adopted for biomimetic mineralization to prepare multilayered nano-entrapped ECL, which were then applied as biocatalysts for the production of fatty acid methyl ester (FAME). The optimal ECL (0.8 mg protein/mL) and CuSO₄∙5H₂O (1.2 mM) showed the highest capacity for enzyme loading. The ECL-CuSO₄-hybrid showed an 89.7% conversion of triacylglycerides into FAME via transesterification and a 98.7% conversion of oleic acid into FAME via esterification at 72 h. The ECL-CuSO₄-hybrid gave 65% and 78.7% FAME production after 5 successive reuses via transesterification and esterification reactions, respectively. Therefore, these ECL-inorganic hybrid biocatalysts have high economical potential to be used for the production of biodiesel as the future petrodiesel replacement.

Enzymatically-synthesized xylo-oligosaccharides laurate esters as surfactants of interest

Lipase-catalyzed synthesis of xylo-oligosaccharides esters from pure xylobiose, xylotriose and xylotetraose in the presence of vinyl laurate was investigated. The influence of different experimental parameters such as the loading of lipase, the reaction duration or the use of a co-solvent was studied and the reaction conditions were optimized with xylobiose. Under the best conditions, a regioselective esterification occurred to yield a monoester with the acyl chain at the OH-4 of the xylose unit at the non-reducing end. Surface-active properties of these pure xylo-oligosaccharides fatty esters have been evaluated. They display interesting surfactant activities that differ according to the degree of polymerization (DP) of the glycone moiety.

Free and Substrate-Immobilised Lipases from Fusarium verticillioides P24 as a Biocatalyst for Hydrolysis and Transesterification Reactions

Fungal enzymes are widely used in technological processes and have some interesting features to be applied in a variety of biosynthetic courses. Here, free and substrate-immobilised lipases from Fusarium verticillioides P24 were obtained by solid-state fermentation using wheat bran as substrate and fungal carrier. Based on their hydrolytic and transesterification activities, the lipases were characterised as pH-dependent in both reactions, with higher substrate conversion in an alkaline environment. Thermally, the lipases performed well from 30 to 45 °C, being more stable in mild conditions. Organic solvents significantly influenced the lipase selectivity using different vegetable oils as fatty acid source. Omega(ω)-3 production in n-hexane achieved 45% using canola oil, against ≈ 18% in cyclohexane. However, ω-6 production was preferably produced for both solvents using linseed oil with significant alterations in the yield (≈ 79% and 49% for n-hexane and cyclohexane, respectively). Moreover, the greatest enzyme selectivity for ω-6 led us to suppose a lipase preference for the Sn1 position of the triacylglycerol. Lastly, a transesterification reaction was performed, achieving 90% of ester conversion in 72 h. This study reports the characterisation and use of free and substrate-immobilised lipases from Fusarium verticillioides P24 as an economic and efficient method for the first time.

Optimization of process variables on two-step microwave-assisted transesterification of waste cooking oil

Scale-up and commercialization of biodiesel is often delimited by costly feedstock that adds up to the process costs. These underlying issues demand the exploration of unconventional cheap feed to improve the process economics. Conversion of waste cooking oil (WCO) into biodiesel could reduce the process costs by 60-70%. However, the continuous exposure to heat during frying leads to oxidation as well increase in the free fatty acid (FFA) content which intensifies the time and energy required for transesterification. The present study analyzes the effect of parameters over the conversion of WCO (with 8.17% FFA) into biodiesel via two-step acid-alkali-based microwave-assisted transesterification. Response surface methodology (RSM) was used to optimize the oil:methanol volume ratio, microwave power, and reaction time during the acid-catalyzed esterification to bring down the FFA below 1%. Microwave irradiation of 250 W, with methanol:oil molar ratio of 19.57:1 [oil:methanol volume ratio of 1.31 (expressed as decimal)] and reaction time of 35 s, resulted in 0.082% of FFA. Alkali-catalyzed transesterification with methanol:oil molar ratio of 5:1 with 2% sodium hydroxide at 65 °C thereby produced fatty acid methyl esters (FAMEs) with the volumetric biodiesel yield of 94.6% in 30 min. Physiochemical properties of the transesterified WCO were well comparable with the biodiesel standards. The study highlights the essentiality of multivariate optimization for the esterification process that could aid in understanding the interactive effects of variables over FFA content. Such studies would benefit in scaling up of the transesterification process at industrial level by improving the economics of the overall bioprocess.

Algal biodiesel production with engineered biochar as a heterogeneous solid acid catalyst

This study evaluates the use of engineered biochar as a heterogeneous solid acid catalyst for transesterification of algal oil derived from a native microalgal consortium. Biochar derived from sugarcane bagasse, coconut shell, corncob and peanut shell were evaluated for catalytic activity following surface modification. Peanut shell pyrolyzed at 400 °C with the sulfonic acid density of 0.837 mmol/g having 6.616 m²/g surface area was selected for efficient catalysis. The efficiency of transesterification was evaluated with 1-7 wt% catalyst loading, methanol: oil ratio of 6:1 to 30:1 at 55-85 °C over 2-8 h. Biodiesel yield of 94.91% was obtained with 5 wt% catalyst loading, MeOH: oil ratio of 20:1 at 65 °C after 4 h. Spectral analysis of algal biodiesel showed the presence of functional groups corresponding to esters. GC-MS analysis revealed the prominent presence of palmitic and oleic acids, further advocating the suitability of the technology for commercial application.

Novel thermostable lipase produced by a thermo-halophilic bacterium that catalyses hydrolytic and transesterification reactions

Lipase belongs to the class of hydrolytic enzymes that are widely used in the biotechnology industries. The goal of this research was to purify and characterize lipase produced from a thermo-halophilic bacterium, namely Pria Laot Sabang 80 (PLS 80). Purification was performed using ammonium sulphate fractionation, followed by gel filtration chromatography using Sepharose Cl-6B. After purification, the enzyme had a specific activity of 326.6 U/mg with a purity of 6.02 higher than the crude extract; with a molecular weight of around 50 kDa. The optimum activity was observed at 70 °C and pH 9. The activity increased in the presence of 10 mM Mn²⁺, K⁺ and Ca²⁺ ions, while Hg²⁺ only slightly increased the enzyme activity. In contrast, the activity decreased in 10 mM Mg²⁺, Zn²⁺, Co²⁺, EDTA, and PMSF. The enzyme showed good hydrolytic activity on long fatty acids substrates (p-nitrophenyl palmitate) with a value of 35.5 U/mL. It was also able to catalyze a transesterification reaction. GC-MS result showed that the biodiesel consisted of methyl octanoate (5.3%), methyl caprate (12.4%), methyl laurate (34.1%), methyl myristate (10.7%), methyl palmitate (3.9%), and methyl stearate (1.2%) when using coconut oil as the substrate. The results suggested that the lipase from PLS 80 had unique attributes that could be useful in various industrial applications.

Feasibility of biodiesel production from waste cooking oil: lab-scale to pilot-scale analysis

In the last few decades, consciousness of fossil fuel resources and increased environmental concerns have given the need for emergence of alternative fuel. Biodiesel is one of the potential renewable energies produced from edible and non-edible biomass which could be a potential alternative for petrol-derived diesel. In this work, initially the process of biodiesel production from waste cooking oil using potassium hydroxide as catalyst and the process parameters were studied in laboratory. The maximum biodiesel yield of 97% was attained at 75 °C with 1 wt% catalyst concentration and oil-methanol molar ratio of 1:06 at 350 rpm and 90 min. Also, these process conditions were used for biodiesel production in the pilot plant and obtained 97% yield. Overall, mass balance for the pilot plant was studied to analyze the product yield loss. The fatty acid methyl ester formation in the plant was confirmed by characterization with FTIR and ¹H NMR. Further, the quality of biodiesel produced was compared for its physiochemical properties with the ASTM standards.

Development of one-step sample preparation methods for fatty acid profiling of milk fat

Determination of the fatty acid (FA) profile of milk fat generally involves total lipid extraction from liquid milk, transesterification and GC analysis. The lipid extraction step is time consuming and often employs toxic solvents such as chloroform. Two alternative methods are presented here that skip the lipid extraction step and allow the determination of FA composition via direct transesterification of dried milk and liquid milk respectively. We have shown that dried milk can be used directly in alkaline-catalysed methylation, whereas direct transesterification of both dried milk and fresh milk is feasible with acidic methanol. Both methods generate similar results as compared to the classical two-step method (i.e. lipid extraction and FA methylation) when optimised methylation parameters (temperature, time, milk and reagent volume) are followed. By omitting the lipid extraction step, these simplified one-step methods offer a much higher throughput and a reduced cost in FA composition analysis of milk samples.

Nano-sulfated zirconia catalyzed biodiesel production from tannery waste sheep fat

This study makes use of tannery waste to produce biodiesel using a nano-sulfated zirconia catalyst (ferric-manganese-doped sulfated zirconia). It was through a modified wetness impregnation method that the catalyst was prepared which was then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The catalytic property of the synthesized catalyst was determined by using it to produce biodiesel from tannery waste sheep fat. A study was carried out to find the effect of the different parameters affecting the process. Optimized conditions of 15:1 methanol to fat molar ratio and catalytic loading of 8 wt% at 65 °C with a stirring rate of 400 rpm for a reaction duration of 300 min gave a maximum yield of 98.7 wt%. The performance of the catalyst during recycling was analyzed by conducting reusability study. The reused catalyst gives a maximum yield above 90 wt% up to five cycles with a catalyst recovery of 88 wt%. ASTM D6751 standard was used to compare the analyzed fuel properties of the biodiesel.

Preliminary techno-economic analysis of biodiesel production over solid-biochar

This study suggests the economic potential of biochar-based biodiesel production by conducting the techno-economic analysis. The itemized cost estimation was performed by categorizing biochar production facility and biodiesel conversion plants for 30,000 ton y-1 of biodiesel production capacity. The result of sensitivity analysis shows the methanol and waste cooking oil (WCO) costs are significantly sensitive to determine a unit biodiesel production cost. When the biodiesel selling price was 1.70 $ kg-1, the discounted payback period was varied from 1.91 (not discounted) to 2.06 years (10% discounted). In addition, the break-even price of biodiesel was calculated to 1.55 $ kg-1 when the discount rate was 10%. It means that this technology is to be feasible because of commercial diesel price (0.97 to 1.88 $ kg-1). The consideration of tax exemption and subsidy for biodiesel can be good option to supply WCO based energy production.

The use of cosolvents in heterogeneously and homogeneously catalysed methanolysis of oil

The paper describes transesterification of oil by methanol with use of cosolvents such as ethyl acetate, tetrahydrofuran, hexane, acetone and diethyl ether at catalyst homogeneous (potassium hydroxide) and heterogeneous (mixed oxides). The cosolvents dissolve oil and methanol to form a single (homogeneous) phase, which increases the reaction rate. Therefore, the biodiesel production will be environmentally friendly because less energy is consumed, which increases sustainability. The whole binodal curve of ternary plots of oil, methanol and cosolvent was determined to find the molar ratio, in which the reaction mixture forms a single phase. The ethyl acetate and tetrahydrofuran have relatively small heterogeneous region, because of the similarity of their electric dipole moment with methanol. After transesterification, the detailed analysis of ester and also glycerol phase was carried out. For homogeneous catalyst, the highest esters content in the ester phase was achieved with tetrahydrofuran. For heterogeneous catalyst, the ester content was lower with cosolvent than without cosolvent, probably due to dilution of reaction components by cosolvent or bonding of cosolvent to the active sites of the catalyst.

Enhanced biodiesel production from waste cooking palm oil, with NaOH-loaded Calcined fish bones as the catalyst

The present work mainly focuses on the development of heterogeneous catalysts from fishbone, loaded with sodium hydroxide for transesterification of biodiesel. The catalyst was developed using a two-step process involving the calcination of fishbone at 900 °C, followed by a hydrothermal process with a sodium hydroxide-loaded (NaOH) solution. The synthesized heterogeneous catalyst was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and BET surface area analysis. The transesterification of waste cooking palm oil (WCO) with BC-NaOH shows a maximum yield of up to 98% for 2.5 wt.% catalyst loading, 1:9 oil:methanol molar ratio at a temperature of 65 °C for a reaction time of 1.5 h. The enhanced catalytic activity is due to the high base active site density of hydroxyl groups from hydroxyapatite, β- tricalcium phosphate, and sodium hydroxide. A gas chromatography-mass spectroscopy (GC-MS) was performed to determine the conversion of oil to biodiesel. The reusability of the catalyst was confirmed from the consistency in the biodiesel yield obtained in up to 7 cycles.

Smart waste management of waste cooking oil for large scale high quality biodiesel production using Sr-Ti mixed metal oxide as solid catalyst: Optimization and E-metrics studies

Biodiesel was prepared at laboratory scale via transesterification reaction from waste cooking oil using Sr-Ti mixed metal oxide as a heterogeneous base catalyst. The solid base catalyst was synthesized by polymer precursor method. The most efficient active phase of catalyst was explored by varying the Sr/Ti atomic ratio in mixed metals oxides. The synthesized catalyst underwent for TGA, Powder XRD, SEM, EDX, FT-IR, XPS, and BET surface area analysis to assess its physicochemical characteristics. Additionally, basicity which has been observed as the most process governing factor was also evaluated through Hammett indicator-benzoic acid titration method. The Sr-Ti mixed metals oxide with 4:1 was observed with highest catalytic activity for methanolysis reaction. Its potency was facilitated by fairly acquired BET surface area (43.6 m²/g) and basic strength (2.89 mmol/g). The appreciable values of both the parameters imparted the high catalytic activity in Sr-Ti mixed metals oxide with atomic ratio 4:1. Onward, transesterification reaction was optimized for the maximum FAME conversion through RSM using CCD. The confirmatory tests showed the consistency with the conclusions drawn from RSM study regarding optimized values of concerned process variables. Transesterification reaction turned out 98% FAME conversion exerting catalyst dose (1.0 wt%), methanol to oil molar ratio (11:1), and reaction time (80 min) at reaction temperature (65 °C) and agitation speed (600 rpm) featured by RSM study. The closeness in optimized value of anticipated and confirmatory results perceived the efficiency of CCD and approving its potency as successful tool to estimate the highest FAME conversion. Next, a pseudo-first-order kinetic model of transesterification reaction was established. In addition to this, the thermodynamic functions were also computed through Eyring plot dictating the non-spontaneity and endergonic nature of transesterification reaction. The Environment-factor (E-factor) and Turn Over Frequency (TOF) were enumerated and they approved the prepared Sr-Ti mixed metals oxide as an efficient and sustainable catalyst for biodiesel production through transesterification. Finally, all the important fuel properties of prepared biodiesel from waste cooking oil was discerned within the range laid by ASTM D-6751 standards for biodiesel which coined the compatibility of prepared methyl ester with CI engines as a substitute of diesel fuel.