Production Of Fatty Acid Methyl Esters Research Articles

Recyclability of Zinc Palmitate-Based Composites in Fatty Acid Methyl Ester Production from Oil Feedstocks at Varied Acidity.

Zinc hydroxide nitrate (Zn5) is one of the layered metal hydroxide materials, which has been extensively reported as an effective bifunctional catalyst for biodiesel production from acidic oils. This report gives a comprehensive summary of the reactivity of Zn5 in the methanolysis of various oil feedstocks, plant oils, free fatty acids, and other acidic oils. Notably, as evidenced by this work, Zn5 is highly effective in converting acidic oils [palmitic acid/palm oil (PO)] to fatty acid methyl ester (FAME or biodiesel) at high yields ranging from 80 to 95%, withstanding acid content up to 10% without soap formation. The high FAME yields result from complex methanolysis and hydrolysis processes, e.g., transesterification of triglycerides in the PO, esterification of palmitic acid, and hydrolysis of the triglycerides. Despite this, Zn5 is nonrecyclable because it is unstable in the reaction media and transforms into zinc hydroxide nitrate/zinc palmitate (Zn5/ZnP) composites. The Zn5/ZnP composites were suitable for use in FAME production from PO at 100 °C for 2 h by using a methanol-to-oil molar ratio of 30:1, yielding high FAME yields of 97 and 70.7% in the first and fourth cycles, respectively. This study added better insight into how to effectively produce FAME from oil feedstocks of varying acidity by using zinc layered hydroxide- or zinc carboxylate-based materials.

Thermal Conversion of Coral Waste and its Utilization as Low-Cost Catalyst for Biodiesel Production

This study investigates the thermal conversion of waste coral and its utilization as a heterogeneous catalyst for biodiesel production from soybean oil. In this work, waste coral is calcined at varied temperatures of 800, 900, and 1000°C, and the effect of the calcination temperature on the physicochemical character of the solid is evaluated through Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and basicity measurement. The results show that the higher temperature facilitates the conversion of CaCO3 of the aragonite and calcite phases in raw waste coral into CaO, achieving a complete conversion at the temperature of 1000°C. Thermal conversion influences the increased surface basicity of the solid, which is associated with the higher activity for biodiesel production. Further studies on the obtained CaO as a catalyst demonstrate the catalyst dosage and the methanol-to-oil ratio as significant factors for fatty acid methyl ester production. The highest yield of 98.7% is achieved after a 3 hours reaction with 8 wt.% catalyst dosage and 9:1 methanol-to-oil ratio. The catalyst exhibits stability with an insignificantly decreased yield until the fifth usage cycle. The optimum conditions and reusability features of the calcined waste coral suggest that waste coral is a favorable CaO catalyst source for biodiesel production.

Transesterification catalyst strength as observed by solution-based oxygen-17 nuclear magnetic resonance spectroscopy

Natural abundance oxygen-17 nuclear magnetic resonance spectroscopy (17O-NMR) was applied to study homogeneous transesterification catalysts for fatty acid methyl ester production. Alkoxide catalysts were made with selected permutations of lithium, sodium, magnesium, and potassium hydroxides with ethanol, methanol, isopropanol, and glycerol. Pilot scale transesterification reactions of Canola oil were completed and the 17O-NMR spectra were collected from the reaction products. The alkoxide solutions showed the downfield shifts relative to the reagent alcohol, in a linear relationship with the concentration of catalyst ion. The electron deshielding of the oxygen of the alkoxide catalyst is observed directly by 17O-NMR, and the fastest catalyst has the largest downfield (high frequency) shift. This effect is most pronounced in potassium methoxide and less pronounced for less polar solvents such as isopropanol.

Optimizing the Conversion of Bio-Oil from Haematococcus pluvialis to Fatty Acid Methyl Esters

AbstractHaematococcus pluvialis microalgae have emerged as a prevalent source of antioxidants in cosmetics and nutritional products. Additionally, numerous researchers have posited the potential of this microalgae to produce fatty acid methyl esters (FAME). Nevertheless, the optimization of the production of FAME from H. pluvialis oil has not been investigated. In this study, the transesterification reaction of H. pluvialis bio-oil was optimized using the response surface methodology, resulting in optimal experimental conditions for an oil to methanol ratio of 1:4.17, at a temperature of 80 °C, with a reaction time of 47 min. The resulting FAME was found to not comply with the biodiesel standard in terms of the content of polyunsaturated fatty acids (6.02%), as well as kinematic viscosity (7.02 mm2/s). Further study is required to reduce these parameters in order to ensure biodiesel quality and compliance with the standard. Nevertheless, its high flash point value of 150 °C and its high thermal stability within the temperature range of 211–290 °C suggest the potential for utilization as a biolubricant.

Electrolysis Approach of Fatty Acid Methyl Ester Production Using Alkali Hydroxides and Their Alkoxides

The depletion of fossil fuels and environmental concerns have led to the search for alternative fuels (biodiesel) derived from renewable resources. Electrolysis is a promising method of fatty acid methyl ester (FAME) synthesis that can be maintained at room temperature. Nevertheless, the low reaction rates have been commonly accelerated using a combination of catalysts and electrolytes. This work proposed a novel electrolyte-free electrolysis approach for biodiesel synthesis from soybean oil using alkaline hydroxide (NaOH, KOH) and alkaline methoxide (NaOCH3, KOCH3)catalysts. Though all of them demonstrated high biodiesel yield, KOCH3 exhibitedthe highest efficiency. Based on response surface methodology, the highest FAME yield of 97.11% was achieved at optimal electrolysis voltage of 18.76V, water amount of 1.97 wt.%, KOCH3 amount of 3.17 wt.%, and methanol/oil of 21.33:1 molar, and reaction time of 60 min. The fuel properties of synthesized biodiesel agreed with international standards.The findings of this work suggest that electrolyte-free electrochemical using alkaline hydroxides and alkaline methoxides as catalysts could be a useful alternative to conventional transesterification method for producing biodiesel. Keywords: Alkaline catalysts, Biofuel, Box–Behnken Design, Electrochemical approach

Biodiesel Production from Waste Cooking Oil Using Recombinant Escherichia coli Cells Immobilized into Fe3O4-Chitosan Magnetic Microspheres.

Developing reusable and easy-to-operate biocatalysts is of significant interest in biodiesel production. Here, magnetic whole-cell catalysts constructed through immobilizing recombinant Escherichia coli cells (containing MAS1 lipase) into Fe3O4-chitosan magnetic microspheres (termed MWCC@MAS1) were used for fatty acid methyl ester (FAME) production from waste cooking oil (WCO). During the preparation process of immobilized cells, the effects of chitosan concentration and cell concentration on their activity and activity recovery were investigated. Optimal immobilization was achieved with 3% (w/v) chitosan solution and 10 mg wet cell/mL cell suspension. Magnetic immobilization endowed the whole-cell catalysts with superparamagnetism and improved their methanol tolerance, enhancing the recyclability of the biocatalysts. Additionally, we studied the effects of catalyst loading, water content, methanol content, and reaction temperature on FAME yield, optimizing these parameters using response surface methodology and Box-Behnken design. An experimental FAME yield of 89.19% was gained under the optimized conditions (3.9 wt% catalyst loading, 22.3% (v/w) water content, 23.0% (v/w) methanol content, and 32 °C) for 48 h. MWCC@MAS1 demonstrated superior recyclability compared to its whole-cell form, maintaining about 86% of its initial productivity after 10 cycles, whereas the whole-cell form lost nearly half after just five cycles. These results suggest that MWCC@MAS1 has great potential for the industrial production of biodiesel.

Modification of Growth Media for Scenedesmus and Nitchzer Species for Fatty Acid Methyl Esters Production in Raceway Pond

The aim of this study was to modify the growth media for Scenedesmus and Nitchzia species for fatty acid methyl esters production in raceway pond. Native Scenedesmus and Nitchzia species were cultivated in raceway pond in three different growth media (Nitrogen-sufficient, Nitrogen-deficient and Blue Green 11) media at different periods to assess their quantitative parameters (biomass concentration (g/L), biomass productivity (g/L/d), lipid content (%), and lipid productivity (mg/L/d) as well as their fatty acid methyl esters composition. The quantitative parameters were determined following standard methods and the fatty acid methyl esters composition was analysed by Gas Chromatography Mass Spectrometry (GC-MS). The results of the quantitative parameters obtained from Scenedesmus species were highest in the Blue Green 11 (control) media as compared to the experimental media. Statistically, there is significant difference (p<0.05) in the lipid content obtained from Scenedesmus species between the Blue Green 11 media and the experimental media. The biomass concentration and lipid content obtained from Nitchzia species were also found to be highest in Blue Green 11 media as compared to the other two media. However, the lipid content obtained from Nitchzia species in the three different media showed insignificant difference (p>0.05). Scenedesmus and Nitchzia species did not respond to nitrogen deficiency condition. The Gas Chromatography Mass Spectrometry analysis of the fatty acid methyl esters composition revealed the presence of similar compounds in different proportion. The dominant compound of the fatty acid methyl esters of the two species in the three different media are Hexadecanoic acid methyl ester ((palmitic acid)), 9-octadecenoic acid (Z) methyl ester ((oleic acid) and 9, 12-octadecadienoic acid methyl ester (linolenic acid) among others. The Carbon16-Carbon18 (C16-C18) chain in Scenedesmus and Nitchzia species ranges from 74.14-61.84% and 63.81-61.98% respectively. These could suggest that both species have a great potential for the production of fatty acid methyl esters in large scale cultivation.

Analysis of Improving the Quality of Fatty Acid Methyl Ester (FAME) Products Against Acid Value (AV) Levels Using the Six Sigma and Kaizen Methods

. PT XYZ is a palm oil derivative processing company that produces biodiesel / FAME (Fatty Acid Methyl Ester) products. However, there are several obstacles that still occur during the company's production process which causes the acid value (AV) level of FAME products to not meet specifications and there are 3% defective products. Therefore, this study aims to determine the improvement plan by applying kaizen to the Six Sigma improvement stage and reducing outspec products in the FAME production process. The results of the research conducted using the six sigma method show that the company has a DPMO value of 71,459 and a sigma value of 2.96 which is in the average position of the industry in Indonesia based on the results of data processing. While recommendations for improvement by implementing kaizen include training machine operators, making standard operating procedures (SOPs) for machine inspections on each shift, reducing the amount of strearin added to AV raw materials before pre-treatment, maintenance and machine calibration. This step are expected to overcome the main problems identified in the study.

Two-stage co-pyrolysis of Kraft lignin and palm oil mixture to biofuels: The role of lignin as a methylation agent for methyl ester formation

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME.

Saccharomyces cerevisiae cellular engineering for the production of FAME biodiesel

The unsustainable and widespread utilization of fossil fuels continues to drive the rapid depletion of global supplies. Biodiesel has emerged as one of the most promising alternatives to conventional diesel, leading to growing research interest in its production. Microbes can facilitate the de novo synthesis of a type of biodiesel in the form of fatty acid methyl esters (FAMEs). In this study, Saccharomyces cerevisiae metabolic activity was engineered to facilitate enhanced FAME production. Initially, free fatty acid concentrations were increased by deleting two acetyl-CoA synthetase genes (FAA1, FAA4) and an acyl-CoA oxidase gene (POX1). Intracellular S-adenosylmethionine (SAM) levels were then enhanced via the deletion of an adenosine kinase gene (ADO1) and the overexpression of a SAM synthetase gene (SAM2). Lastly, the S. cerevisiae strain overproducing free fatty acids and SAM were manipulated to express a plasmid encoding the Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). Using this combination of engineering approaches, a FAME concentration of 5.79 ± 0.56 mg/L was achieved using these cells in the context of shaking flask fermentation. To the best of our knowledge, this is the first detailed study of FAME production in S. cerevisiae. These results will provide a valuable basis for future efforts to engineer S. cerevisiae strains for highly efficient production of biodiesel.

Sulfonated reduced graphene oxide catalyzed fatty acid methyl ester production from macroalgae Dictyota dichotoma in supercritical conditions

Despite proposed alternative fuels in the recent past, the race for a natural substitute still exists. In this research work, we suggest biodiesel preparation from the rarely explored macroalgae D. dichotoma using a supercritical fluid system of ethanol/ THF. Reduced graphene oxide was prepared using dried jasmine powder as bio-reductant. Reduced graphene oxide was sulphonated using sulfanilic acid, and the catalysts were characterized by XRD, BET surface area, FTIR, and SEM techniques. The reaction conditions for algal oil conversion into biodiesel in supercritical ethanolysis were optimized. FTIR, and GCMS were eployed as analytical tools to analyze the produced biodiesel. The optimized reaction conditions were 265 °C, ethanol: algal oil= 15:1, Reaction time = 10 min, catalyst loading = 5% GO, and THF: ethanol −0.4 for 78% FAEE yield using GO. 10 wt% S-rGO yielded a maximum of 89% FAEE; and 22.55% C18:2. The catalyst was efficient till five cycles. The work assures the utility of abundant macroalgae for alternative fuel production.

Maximizing the potential of commercial zinc stearate for one-pot esterification and transesterification for high-acidity biodiesel production

Meeting the growing demand for energy while combating the adverse effects of global warming remains challenging today, and biodiesel offers a potential solution to help mitigate the impact of global warming. In this scenario, our primary goal was to optimize biodiesel production from highly acidic soybean oil using a one-pot esterification and transesterification process, addressing the challenges associated with high-acidity substrates. To start, X-ray Diffraction (XRD) guaranteed us just one phase for each commercial catalyst, and we conducted catalytic experiments to select the most suitable Zn-based material for the process, choosing zinc stearate (ZnSt2) as the best candidate. Our study demonstrated that a nano-sized zinc oxide (ZnO) catalyst, which was anticipated to be the most suitable choice, did not exhibit optimal performance. Subsequently, a Full Factorial Design of Experiments (DOE) was employed to optimize reaction parameters, specifically, the reaction temperature and the oil-to-methanol (O:M) molar ratio. The results consistently showed that increased O:M ratio and temperature promoted enhanced fatty acid methyl esters (FAME) production and reduced acidity. Then, experiments were conducted to maximize FAME production and minimize free fatty acid (FFA) content. The results showed that increasing the catalyst concentration from 5 wt% to 10 wt% did not significantly impact FAME production or acidity reduction. Also, while increased methanol should theoretically enhance FAME production and reduce acidity, the results were inconsistent across all experiments. Excess methanol interfered with glycerol separation, leading to decreased FAME yield. Thus, this study underscores the complexity of biodiesel production and highlights the importance of selecting suitable catalysts and optimizing process parameters.

Enhanced Mixing Towards the Production of Fatty Acid Methyl Esters by In Situ Transesterification of Eucheuma Cottonii: Experimental and Computational Fluid Dynamics (CFD) Analysis

Biodiesel is one of the alternative replacements for the conventional fossil fuel-based diesel as the demand for energy is increasing with the increasing world population. The production of biodiesel (also known as fatty acid methyl esters (FAME)) from macroalgae (E. cottonii) is the focus in this study. Conventionally, production of FAME from macroalgae will be carried out through the two-step transesterification processes, which consists of extraction of algal oil (lipids and free fatty acids) and subsequent transesterification step. However, the two-step transesterification method is time and energy consuming processes and thus ways to enhance the production yield of the biodiesel produced are being studied. This paper concentrates on utilization of enhanced mixing technique via in situ transesterification (ISTE) process in FAME production which elucidate the effects of reaction time and mixing intensity. The ISTE reaction was carried out at the ratio of biomass: Methanol (MeOH): Hydrochloric Acid (HCl) (w/v/v) of 1:20:5 and a reaction temperature of 60 °C. The total reaction time for the reaction was 90 minutes, where samples were collected at 30 minutes interval. The increase in reaction time and mixing intensity gave a significant positive impact on the production of FAME. At 90 minutes of reaction time and impeller rotational speed of 900rpm, the maximum amount of methyl palmitate and methyl stearate produced were 0.5729 wt% and 0.0559 wt% respectively. The results of contour of volume fraction (VF) of palmitic acid obtained from Computational Fluid Dynamics (CFD) analysis from the Aspen Fluent Software is in good agreement to the experimental results of the study.

Fatty acid methyl ester production from rainbow trout waste oil using microwave-assisted transesterification

The desirable oil content of Rainbow Trout waste makes it a valuable resource for the industrial-scale production of biodiesel. Limited research has been conducted regarding the utilization of microwave-assisted transesterification (MAT) as a cost-effective method for biodiesel production from this accessible resource. In this study, MAT was optimized in terms of reaction time (1–5 min), microwave power level (100–500 W), methanol/oil molar ratio (3−15), and catalyst concentration (0.3–1.5%). The optimal condition was reaction time of 4 min, microwave power 300 W, molar ratio of 12, and catalyst concentration of 1.2%, ensuring utmost efficiency and purity. In addition, MAT was compared to ohmic-, ultrasonic probe-, ultrasonic bath-, and magnetic stirrer-assisted transesterification techniques, assessing physicochemical properties, energy consumption, and thermal properties of produced methyl esters. The microwave, ohmic, and ultrasonic probe showed superior efficiency, briefest reaction time, and minimal pouring and cloudy values, respectively. Additionally, these techniques consumed only 5.3, 5.7, and 6.7 Wh/g, respectively, signifying the lowest energy usage. Conversely, magnetic stirrer and ultrasonic bath showed less desirable performance. Overall, MAT can be suggested as a novel and effective technique for enhancing efficiency, reducing reaction time, and decreasing energy consumption in the production of marine waste oil methyl esters.

Ultrasound-assisted production of biodiesel from oils with saturated and unsaturated fatty acids

The reaction of biodiesel or FAME (Fatty Acid Methyl Esters) production can become especially slow because of the mass transfer between the non-polar phase (oil) and polar (alcohol) is one of the critical factors. Thus, different technologies have been developed to reduce the reaction time . One of them is ultrasound. Ultrasound is an acoustic wave with a frequency greater than the upper limit of human hearing. In the present work biodiesel from oils rich in unsaturated fatty acids (rapeseed and soybean) and saturated (coconut and palm) has been synthesized using ultrasound as auxiliary energy. For this, an ultrasonic probe at a fixed frequency of 20 kHz and 450 W of power was used. Moreover, it attempted to determine if the chemical composition affects the ultrasound assisted biodiesel synthesis... FAME yields were evaluated in the different oils. The rapeseed, soybean and palm yields achieved above 90 % wt., close to meet with European standard UNE EN 14003, but coconut oil was just over 80% wt. conversion. Thus, it was observed that the differences between the oil yields are determined by chain length of the fatty acids that form part of the triglyceride. Coconut oil has mainly short chain fatty acids opposed to rapeseed, soy and palm fatty acids having 16 carbons or higher. Regarding the reaction time, it was reduced significantly compared to conventional transesterification.

Microalgal synthesis of the biodiesel employing simultaneous extraction and esterification via heterogeneous catalyst

Within the realm of biorefinery, the third generation of biodiesel production relies on extracting oil from Algae to create renewable fuels. Algae cultivation can occur under precise laboratory conditions, making them a sustainable substitute for Fatty Acid Methyl Ester or biodiesel production. Through analysis of the simultaneous extraction and (trans)esterification process of Algae Chlorella Minutissima utilizing sulfated carbonaceous catalysts, scientists have discovered an efficient technique for producing biodiesel. Various parameters, such as catalyst loading, oil-to-methanol ratio, reaction temperature, and reaction time for FFA reduction and FAME yields, were studied and optimized. Results indicate that utilizing a 10 wt% catalyst loading and a 70:30 volumetric oil to methanol ratio can achieve 67.59 % FFA reduction and a biodiesel yield of 44 mL. This method of producing biodiesel can occur in a single-unit operation, leading to higher yields of renewable fuel at a reduced cost and energy consumption. Finally, the quality of the biodiesel produced met ASTM D6751 standards, confirming its suitability for use.

Fatty acid methyl esters production from crude waste frying oil using modified coffee husk ash catalyst: Parameters optimization

In this study, a KNO3-loaded coffee husk (CH) ash catalyst was synthesized to produce waste frying oil methyl ester (WFOME) from crude waste frying oil (WFO). Taguchi method optimization was performed to identify the best set of reaction temperature, time, catalyst loading and methanol to WFO molar ratio for maximum WFOME yield. A catalyst composite material (CCM) which is a mixture of CH char and KNO3 (0–65 wt%) was calcined to obtain the catalyst. The KNO3 loading and CCM calcination time effects on the catalyst performance and physicochemical properties were examined. The combustion behavior of the CH and CCMs was investigated using thermal analysis techniques. Utilizing FTIR, XRD, BET, SEM, and pH measurements, the catalyst characterization was carried out. For analytical sample sizes (during thermal analysis) with high KNO3 loading, the thermal reactivity was higher. However, for larger sample sizes (during catalyst synthesis) higher KNO3 loading decreased the CCM global thermal reactivity due to an oxygen permeation resisting ash deposition on the top surface. Thus, KNO3 tuned the catalyst’s physicochemical properties as a function of its loading (optimum 45 wt%) by affecting the combustion characteristics of the CCMs and basic site concentration. The optimum WFOME yield was 97.99 wt% at a reaction temperature of 65 °C, a reaction time of 1.13 h, a catalyst loading of 5.42 wt%, and a methanol to WFO molar ratio of 13.55:1. The WFOME yield was dropped by 46.93 wt% in three consecutive catalyst reuse tests because of active components leaching.

Potential of algal oil production from secondary treated sewage: a study using Chlorella vulgaris and synthetic wastewater

ABSTRACTTo assess the potential of using the secondary treated wastewater for the production of algal biofuel, batch experiments were carried out in photobioreactors using indigenous Chlorella vulgaris isolated from the natural freshwater body. Secondary treated wastewater with partial nitrification was simulated using various proportions of NO3-N and NH4-N while keeping the total nitrogen the same. Experiments with similar concentrations of nitrate without the NH4-N were used for comparison. In the presence of only NO3-N in the concentration range of 9–37 mg/L, the growth and fatty acid methyl ester (FAME) production was similar to the literature reports. When NH4-N was present along with NO3-N, the biomass growth was adversely affected, indicating an impact on the metabolic activity. For the same initial concentrations of nitrate in the culture, the maximum biomass concentration was reduced by 50–60% in the presence of NH4-N. The FAME profile changed significantly and a new FAME was identified, suggesting an impact on the lipid synthesis pathway. Comparison and analysis with the help of existing literature indicated that the adverse effect due to NH4-N was a function of pH. The growth, biomass yield, and FAME production were unaffected by a wide range of phosphorus concentrations. Maximum fatty acid methyl ester (FAME) suitable for biodiesel production (fatty acid carbon chain length C16 to C18) was 381.01 mg/L (224.58 mg/g of dry biomass), produced at NO3-N concentration of 18.5 mg/L and initial nitrogen loading per unit biomass of 0.37 g NO3-N/g of dry biomass.

BaO as a heterogeneous nanoparticle catalyst in oil transesterification for the production of FAME fuel

Metal oxide-based catalysts play an important role in the transesterification reaction of vegetable oils for fatty acid methyl ester (FAME) production. Additionally, nanocatalysts demonstrate high efficiency due to their increased surface area, higher catalytic activity, and easy operational procedures. Thus, the main objective of this work is to investigate FAME production from sunflower oil using barium oxide (BaO) nanoparticles. BaO was synthesized through one-pot sol–gel reactions and was analysed by several techniques, such as X-ray diffraction (XRD), transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence(EDXRF), N2 adsorption–desorption of liquid nitrogen at 77 K [Brunner–Emmett–Teller (BET)] for surface area measurement and UV–Vis spectroscopy. BaO behaved as an efficient catalyst in the transesterification of oils into FAMEs. Furthermore, the impacts of a variety of reaction parameters on the biofuel yield were explored. The catalyst with 4.7 wt% has the maximum yield of 78.38 % achieved under the optimized reaction conditions (70 °C, 1:20 M ratio of oil:methanol). The characteristics of the resulting methyl ester partially agreed with international FAME standards, making it suitable for use as a blend with petroleum diesel in proportions defined by volume according to the specifications of the American Society for Testing and Materials(ASTM). The catalyst was also evaluated for reusability tests, and the reusability through the reaction showed less than a 7 % conversion drop after 3 runs and 14.6 % after 5 runs.

Evaluating nutrient limitation in co-culture of Chlorella pyrenoidosa and Rhodobacter sphaeroides

The influence of nitrogen deficiency on microalgae-bacteria co-culture has been studied mostly with nitrogen-fixing bacteria. Photosynthetic bacteria (PSB), which are non-nitrogen-fixing bacteria, the impact of N deficiency on its co-culture with microalgae is unknown. In this study, Chlorella pyrenoidosa and Rhodobacter sphaeroides co-culture was cultivated photoheterotrophically with acetate. The impact of N starvation and different P supply levels on oil production were examined. When phosphorus was sufficient, N starvation increased the fatty acid methyl ester (FAME) content from 21.7 % to 28.2 %, and also increased the FAME yield (g CODFAME/g CODAcetate) from 0.17 to 0.22. However, the biomass and FAME productivities decreased. Sufficient phosphorus was also essential for a high growth rate and FAME productivity. Deficiencies in either N or P led to a decrease in the proportion of unsaturated FAMEs. iTRAQ analysis indicated N starvation promoted oil accumulation by driving the carbon flow to fatty acid synthesis in microalgae from co-culture. This study improves the understanding of biomass and lipid production via microalgae-PSB co-culture in photoheterotrophic cultivation. The mechanism of interaction between microalgae and bacteria needs further study.