Biodiesel Quality Research Articles

Enhanced carotenoid production, biodiesel quality, and harvesting efficiency in microalga Graesiella emersonii via heterotrophic cultivation strategy

The aim of this study was to evaluate the potential industrial applicability of the green microalga Graesiella emersonii GEGS21 by comparing its biomass, photosynthetic pigments, and biodiesel properties under photoautotrophic (PA) and heterotrophic (HT) cultivation. Four agricultural soluble fertilizers (SFs) were tested as substitute medium for algal growth. Of these, three were not only cost-effective but also more efficient in promoting growth compared to the BG-11 algal medium. Supplementing the SF medium with 12 g/L of glucose significantly improved algal biomass productivity under HT condition, and the optimal conditions were identified as 0 M NaCl, a temperature of 30 °C, and a pH of 8. Subsequent supplementation with yeast extract led to a notable enhancement in algal growth, resulting in approximately 18.6-times higher biomass productivity compared to the PA condition. Under HT cultivation, the productivities of the photosynthetic pigments including lutein and zeaxanthin were significantly increased approximately by 3.6-fold and 3.5-fold, respectively compared to the PA condition (p < 0.05). Moreover, HT cultivation led to improved biodiesel properties, such as iodine value, cetane number, oxidative stability, and kinematic viscosity. These enhancements, achieved through altered fatty acid methyl ester composition, align with the ASTM D6751 and EN14214 biodiesel standards. Interestingly, when cultivated under HT conditions, algal strain exhibited higher sedimentation efficiency, accompanied by an enhanced cellular starch content, compared to both PA and mixotrophic conditions. This suggests a promising strategy for economically viable harvesting by altering the specific gravity of algal cells. In conclusion, our findings suggest that HT cultivation of Graesiella emersonii GEGS21 may serve as an effective approach to produce value-added compounds and bioenergy, offering potential for economical harvesting.

Silica Based Material as a Potential Adsorbent in Reducing Sterol Glucoside Level in Palm Oil Biodiesel

In recent years, biodiesel has emerged as a popular alternative to fossil fuels due to its superior properties. However, the presence of bioactive compounds, known as sterol glucosides (SGs), in crop-based biodiesel has posed a challenge for producers, as they act as crystal seeds and can cause gel formation or precipitation in cold temperatures. This can lead to issues with the quality of biodiesel during storage or use in vehicle engines. To address this issue, a study was conducted to explore the use of silica-based materials as an adsorbent to reduce SGs concentration in palm oil biodiesel. Natural resources silica material with a size of less than 100 µm was used in the process. The results showed that the use of silica gel led to the removal of 63.09 % of SGs in palm-based biodiesel due to its high surface area (556 m2/g) and porosity (0.79 cm3/g). Fourier transform infrared spectroscopy (FTIR) analysis indicated that the silicate and hydroxyl groups on the adsorbent’s surface were responsible for SGs adsorption. Importantly, the quality of the biodiesel before and after the adsorption treatment met all the specifications of the EN 61214 standard. This research suggests that the use of silica-based materials could be a promising solution for reducing SGs concentration in crop-based biodiesel, and could potentially improve its overall quality.

Analysis of Calophyllum Inophyllum Biodiesel Combustion with Variations of Magnetic Field Strength

The problems facing the world today are limited fossil fuels and increasing global warming due to fuel emissions. Therefore, there is a need to transition from fossil energy to alternative energy that is environmentally friendly and renewable. Biodiesel is an alternative material that can be used as a substitute for diesel fuel. This research aims to improve the combustion quality of calophyllum inophyllum biodiesel using the magnetic field influence method. The combustion test method uses a Bunsen burner and variations in magnetic strength of 4000 gauss, 8000 gauss and 12000 gauss are given. The equivalent ratios used in combustion analysis are 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1:1.1, and 1:1.2. The fuel and air flowing in the Bunsen pipe are heated to a constant temperature of 250°C for the fuel evaporation process. Then the resulting flame was analyzed for its combustion characteristics with RGB color variables, laminar burning velocity, and flame height. The research results show that the stronger the magnetic field effect, the more optimal the combustion quality will be. This is indicated by the increasingly strong magnetic field effect exerted on the flame, causing the red color intensity to decrease, the laminar burning velocity to increase, and the flame height to decrease. This is because the magnetic field can influence the movement of O2 molecules and cause a change in the orientation of the hydrocarbon from para to ortho. As a result, diffusion combustion becomes minimal and the combustion reaction becomes faster.

Total Lipid Content and Fatty Acid Composition of Two Morphologically Distinct Chlorella spp. for Biodiesel Production

This study investigated the potential of two morphologically distinct Chlorella spp. to assess the total lipid content and fatty acid composition targeting biodiesel production. Due to their rapid growth, less space requirement, and zero-conflict with current food demand, green microalgae-led biodiesel production has gained a key attention as an alternative, sustainable and eco-friendly substitute for fossil fuels diminishing the increased demand for fossil fuels, fuel prices and excessive release of greenhouse gases to the atmosphere. The Chlorella spp. were isolated from Beire Lake, Colombo (Wet Zone) and Kiriibban Lake, Monaragala (Dry Zone) of Sri Lanka. They were named as BCS1 and RCS2, respectively. Semi-mass culturing of Chlorella spp. in BG-11 medium (pH=7.5-8.5) was carried out in a greenhouse providing aeration and a 12:12 light: dark photoperiod. After 4 weeks, Chlorella spp. were harvested using aluminium sulphate, employing flocculation method. Harvested biomass was oven-dried and made into a fine powder for analysis. The total lipid content (TLC) of Chlorella spp. was determined using n-hexane as the extraction solvent in a soxhlet extractor maintaining three replicates for each. Extracted lipids were dried in a rotary evaporator and TLC was calculated gravimetrically. The total lipid content of BCS1 and RCS2 was recorded as 15.67% and 18.33%, respectively. After quantification, lipids were resuspended and concentrated in 1 mL of n-hexane to convert into fatty acid methyl esters (FAMEs)/ biodiesel via a transesterification reaction. The trans-esterified lipids (FAMEs) were analysed via Gas Chromatography. The most dominant FAMEs of BCS1 were palmitic acid (C16:0), oleic acid [C18:1 cis (n9)], stearic acid (C18:0), lignoceric acid (C24:0), lauric acid (C12:0) and myristic acid (C14:0). The most dominant FAMEs of RCS2 were cis-10-pentadecenoic acid (C15:1), elaidic acid [C18:1 trans (n9)], linolelaidic acid [C18:2 trans (n6)], cis-11-eicosenoic acid [C20:1 (n9)], lignoceric acid (C24:0) and oleic acid [C18:1 cis (n9)]. A well-balanced saturated and unsaturated FAME composition is essential for the optimal biodiesel quality, herein it was found in BCS1 with 41.62% of palmitic acid and 33.38% of oleic acid. Higher percentage of oleic acid exhibits a combination of oxidative stability and low temperature properties determining the suitability of BCS1 as a biodiesel feedstock compared to RCS2. In conclusion, even though RCS2 has a higher total lipid content, BCS1 exhibits more favourable characteristics in its FAME composition as a promising feedstock for biodiesel production.&#x0D; &#x0D; Keywords: Green microalgae, Chlorella spp., Total lipid content, Lipid composition, Biodiesel

Biodegradation of phenolic derivatives by Rhodosporidium toruloides: Effect on growth, cell morphology, lipid and biodiesel production

Phenol derivatives are considered one of the most hazardous pollutants, posing a significant risk to the ecosystem. The present study investigates the ability of the Rhodosporidium toruloides 9564T to degrade the selected phenol derivatives, i.e., catechol, 4-chlorophenol (4-CP), and 4-nitrophenol (4-NP), and simultaneously produce lipids. The experiments were performed using minimal salt media with varying ranges of catechol (0.25 g/L–1.5 g/L), 4-CP (0.25–1.5 g/L), and 4-NP (0.1–1 g/L) with a 10 % inoculum size. Results showed that R. toruloides 9564T completely degraded 1 g/L catechol, 0.5 g/L 4-CP, and 0.1 g/L 4-NP. In comparison with the two phenol derivatives, the maximum biomass (2.096 ± 0.093 g/L), total lipid (0.774 ± 0.031 g/L), and lipid content (36.92 ± 0.147 %.) produced during catechol degradation. The GC analysis revealed the percentages of saturated fatty acids in lipids were 66.21, 86.43, and 81.39 % for catechol, 4-CP, and 4-NP. Catechol, 4-CP, and 4-NP biodiesel qualities (cetane number, cloud point, pour point, viscosity, etc.) matched ASTM-D6751 and EN 14214. To assess the potential environmental impact, the degraded samples by yeast were analyzed for phytotoxicity, which exhibited reduced toxicity. Consequently, R. toruloides proves to be a promising agent for valorizing wastewater treatment for biodiesel production.

Coupling anaerobic co-digestion of winery waste and waste activated sludge with a microalgae process: Optimization of a semi-continuous system

Wine production represents one of the most important agro-industrial sectors in Italy. Wine lees are the most significant waste in the winery industry and have high disposal and storage costs and few applications within the circular economy. In this study, anaerobic digestion and a microalgae coupled process was studied in order to treat wine lees and waste activated sludge produced within the same facility, with the aim of producing energy and valuable microalgae biomass that could be processed to recover biofuel or biostimulant. Chlorella vulgaris was cultivated on liquid digestate in a semi-continuous system without biomass recirculation. The best growth and phytoremediation performance were achieved applying a hydraulic retention time (HRT) of 20 days with a stable dry weight, lipid and protein storage of 1.85 ± 0.02 g l−1, 33.48 ± 7.54 % and 57.85 ± 10.14 % respectively. Lipid characterization highlighted the potential use in high quality biodiesel production, according to EN14214 (<12 % v/v linolenic acid). The microalgae reactor’s liquid output showed high removal of ammonia (95.72 ± 2.10 %), but low organic soluble matter reduction. Further semi-continuous process optimization was carried out by increasing the time between digestate feeding and biomass recovery at HRT 10. These operative changes avoided biomass wash-out and provided a stable phytoremediation of the digestate with 84.58 ± 4.02 % ammonia removal, 33.01 ± 1.44 % sCOD removal, 38.06 ± 2.65 % of polyphenols removal.

Biodiesel quality improvement by mixing the Azadirachta indica and Moringa stenopetala seed oil (in situ hybridisation) via transesterification process

ABSTRACT Biodiesel is considered environmentally benign, biodegradable, and greener fuel derived from vegetable oils, animal fats, and algae, superseding petroleum products. Hybridisation of vegetable oil has not been widely examined to produce biodiesel with ameliorated quality. This study aims at hybridising Azadirachta indica and Moringa stenopetala seed oils to produce the hybrid biodiesel with improved quality. The Box-Behnken Design was used in design of the experiment and analysis of results. Catalyst dose, oil hybridisation ratio, and reaction time were experimental variables with 3 levels, whereas, agitation speed, oil-to-methanol molar ratio, and reaction temperature were constants. The oil hybridisation ratios were: 25% A. indica and 75% M. stenopetala oil, 50% A. indica and 50% M. stenopetala oil, and 75% A. indica and 25% M. stenopetala oil. Seventeen experimental runs were conducted and the quadratic model was developed at P < 0.0001(significant). The model was determined by analysis of variance (ANOVA) and determination coefficients at 5% LSD.

Cattle wastewater treatment using green microalga Coelastrella sp. KNUA068 as a promising bioenergy feedstock with enhanced biodiesel quality.

Global water scarcity increased the demand for clean water, leading to attention on microalgae-based biological treatment for wastewater due to economic feasibility and sustainable biomass applications. This study isolated indigenous microalga Coelastrella sp. KNUA068 from a wastewater treatment plant, observed its admissible growth rate in diluted cattle wastewater (DCW), and used it for wastewater treatment analysis. The microalga showed high growth rates in indoor and outdoor cultivation with 100% DCW. In addition, the ammonia nitrogen and nitrate nitrogen removal rates of the microalga were 69.97 and 60.35%, respectively, in indoor cultivation, and 50.63 and 67.20%, respectively, in outdoor cultivation. Carotenoid content analysis revealed lutein as the highest productivity carotenoid, and zeaxanthin production was higher in outdoor cultivation. The biomass exhibited suitable biodiesel quality with a cetane number of 50.8 for high-quality biodiesel production. Coelastrella sp. KNUA068 demonstrates potential for bioenergy feedstock, carotenoid production, and wastewater treatment.

Application of waste derived magnetic acid-base bifunctional CoFe/biochar/CaO as an efficient catalyst for biodiesel production from waste cooking oil

The loss of active components, weak acid resistance, and low recover efficiency of common Ca-based catalysts limited its further development and application. In this study, to effectively produce biodiesel from waste cooking oil (WCO), a green and recyclable magnetic acid-base bifunctional CoFe/biochar/CaO catalyst was prepared from sargassum and river snail shell waste via hydrothermal method. The catalysts' structure and properties were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), CO2/NH3 temperature programmed desorption (CO2/NH3 TPD), etc., The prepared catalyst mainly consisted of the carbon skeleton, CoFe alloy, and CaO. CoFe alloy provided catalyst's ferromagnetism for magnetic separation as well as acid sites for transesterification of WCO. Ca and other metal species with nanoscale (∼5.64 nm) were dispersively anchored on sargassum biochar surface, thereby leading to good catalytic activity (99.21% biodiesel yield) and stability (91.70% biodiesel yield after the 5th cycle). In addition, response surface methodology-Box-Behnken design (RSM-BBD) revealed the optimal operational conditions were 16:1 methanol/oil molar ratio, 3 wt% catalyst dosage, 73 °C for 157 min. The maximum biodiesel yield predicted value was 98.29% and the experimental value was 99.21%, indicating good satisfaction of the established model. Moreover, the quality of WCO biodiesel met the ASTM D6751 standards. This study benefits magnetic waste-derived acid-base bifunctional catalysts for the disposal of WCO towards sustainable biodiesel production.

Oxygenated bio-fuel synthesis in reactive distillation: A technological reform under process intensification

Chemical Engineering processes demands separation of reaction products to obtain them in purest form. Reactive Distillation facilitates this feature by incorporating a reactive zone for reaction between conventional rectifying and stripping zone for distillation. It also aid for solid catalyst incorporation of amphoteric nature to avoid repetitive addition of catalyst for different experimental run and will also improve the product yield. The other beneficial features of Reactive Distillation include reduced synthesis cost, reduced utility space required and higher selectivity. This technique is introduced in this paper for synthesis of oxygenated bio-fuel. For this, fuel additive of ether family namely Tert Amyl Ethyl Ether (TAEE) is synthesized using ethanol. Similarly, Biodiesel synthesis is done using transesterification of waste cooking oil with methanol. Both fuel-oxygenate (TAEE) and biodiesel are then blended in varying proportion to improve ignition quality of biodiesel fuel. The study is done experimentally and analyzed under object oriented modeling mode in simulation. Optimization of synthesis process is done using revamping in experimental mode corresponding to sensitivity analysis in simulation. The congruence results show that purity of 95 % and 65 % for biodiesel and TAEE respectively is obtained in reactive distillation corresponding to reboiler duty of 2 kW and reflux ratio 4.

Biodiesel production from hempseed (Cannabis sativa L.) oil: Providing optimum conditions by response surface methodology

This study focuses on the optimization of biodiesel synthesis using non-edible hempseed oil as the feedstock. The response surface method was used to find the best methanol: oil molar ratio, catalyst concentration, reaction temperature, and reaction duration for the transesterification process. The center composite design experimental design was used to make the design. A total of 30 cycles were conducted to adjust the four parameters at five different levels in order to optimize the biodiesel production process. It was found that the best conditions for transesterification of hempseed oil were a KOH catalyst concentration of 0.80 wt.%, a molar ratio of 7.41:1, a reaction time of 62.83 min, and a reaction temperature of 61.92 °C. Under these optimized reaction conditions, the predicted biodiesel yield was 95.57%, while the experimental yield was 95.24%. The biodiesel produced using the optimized parameters was analyzed for its properties, and the findings demonstrated that it met the requirements of EN 14214, a standard for biodiesel quality. The optimization of the biodiesel synthesis process using non-edible hempseed oil contributes to the exploration of alternative and sustainable feedstocks for biodiesel production. The values of the produced biodiesel within the standard range demonstrate its suitability for commercial applications and strengthen the potential of hemp seed oil as a suitable raw material for biodiesel production.

Production of biodiesel from low-quality vegetable oils with a high content of free fatty acids by alkaline transesterification

The extraction of natural fats as well as the production of derived products based on them are renewable processes that play a major role in the modern energy industry. An example in this regard is the so-called biodiesel fuel which is Fatty Acid Methyl Esters (FAME), the production of which in recent years has reached enormous scales. Its main advantage is that it is an ecological product (methyl ester of higher fatty acids), which before and after use does not pollute the environment. Quality biodiesel fuel, in turn, is obtained from quality raw materials, which invariably limits its production. On the other hand, every year as a result of improper storage or processing, as well as obtained as waste products huge amounts of low-quality oils remain unutilized and they in turn, represent a valuable raw material and source of energy after their conversion into biodiesel fuel. The present work investigates the possibility of obtaining methyl esters of fatty acids (biodiesel) from low-quality (bad-quality) vegetable oils with high acid values by transesterification with an alkaline catalyst, which includes the selection of suitable catalysts and conditions for the optimal course of the process.

Pengaruh Durasi, Suhu dan Rasio Reaktan Reaksi Transesterifikasi pada Kualitas Biodesel dari Minyak Biji Kesambi (Schleichera Oleosa Lour)

Abstract. Kesambi oil (Schleichera oleosa Lour) is one of the potential raw materials for biodiesel production. The purpose of the study was to determine the factors that influence the process of making biodiesel from kesambi seed oil. Cassava seed oil was reacted with methanol, with a mass ratio of 7:2 using KOH as catalyst with 1%-ww of catalyst. The reaction was carried out using a stirred reactor operated for at a stirring speed with a reaction time of 45, 60, 75 and 90 minutes, with temperature variations of 55oC and 60oC. The quality of biodiesel was measured by viscosity, density, acid number and iodine number; while the transesterification performance was measured by % yield. Temperature and reaction time that provided biodiesel that met SNI 7182:2012 and gave the highest yield used for further experiments, it was best to re-produce biodiesel with a ratio of reactants mass ratio of kesambi seed oil and methanol 7:1,5;7:2, 5; and 7:3. Parameters measured were viscosity, density, acid number, iodine number and %yield. The biodiesel yield obtained at a temperature of 55oC with a reaction time of 60 minutes with a reactant ratio of 7:2, and at a reaction time of 90 minutes with a reactant ratio of 7:1,5, 7:2, 7:2.5 and 7:3 had density, viscosity, acid number and iodine number. met SNI 7182:2012,. %Yield with a reactant ratio of 7:2.5 is 92.07%, and transesterification at a temperature of 60oC did not produce biodiesel that met SNI 7182:2012.&#x0D; &#x0D; Keywords: biodiesel, reaction duration, reactant ratio, reaction temperature.

Bicarbonate-assisted microalgae cultivation for drinking water RO reject recycling and bioproduct generation

This study undrapes a microalgae-mediated approach for recycling drinking water reverse osmosis (RO) reject with bicarbonate supplementation. Among the tested strains, Chlorella pyrenoidosa exhibited a significantly (p ≤ 0.05) higher biomass growth (760.81 ± 34.24 mg L−1) at 4.0 g L−1 bicarbonate in RO reject. Whereas Scenedesmus sp. showed the maximum biomass yield of 1041.81 ± 33.32 mg L−1 in RO reject without bicarbonate. Moreover, bicarbonate in RO reject promoted biofuel precursor synthesis, with Scenedesmus obliquus and Chlorella sorokiniana acquiring maximum carbohydrate (339.41 ± 13.68 mg L−1) and lipid (1453.57 ± 44.29 mg L−1) yields at 0.5 and 1.0 g L−1 bicarbonate, respectively. The fatty acid methyl ester (FAME) and theoretical methane potential (TMP) analyses showed improved biodiesel quality and biogas yield from bicarbonate-supplemented RO reject-grown microalgal biomass. Thus, the present findings inferred that bicarbonate supplementation to RO reject could be an economically feasible approach for RO reject recycling and microalgae-mediated resource recovery.

CO2 to green fuel converter: Photoautotrophic-cultivation of microalgae and its lipids conversion to biodiesel

This research focused on utilizing photoautotrophically-cultivated microalgae as efficient converters of CO2 into high-quality renewable biodiesel. This study investigated the feasibility of capturing CO2 from the atmosphere (0.04 % CO2) and simulating industrial sources (20–40 % CO2) for utilization as a simulated waste carbon source for the growth and biodiesel feedstock accumulation of three photoautotrophically-cultivated microalgae species, including Chlorella sp. AARL G049, Tetradesmus obliquus AARL G090, and Desmodesmus opoliensis AARL G085. The results demonstrated that all the tested microalgae are promising CO2-to-fuel converters due to their ability to efficiently convert CO2 into lipid-rich biomass, which can subsequently be processed into biodiesel. All three strains of microalgae displayed remarkable CO2 capture capabilities as well as significant biomass production and lipid accumulation, with the highest performance observed under a 20 % CO2 concentration. The microalgae demonstrated CO2 fixation rates ranging from 0.020 to 0.072 g-CO2/L/day, leading to significant improvements in both biomass productivity, which ranged from 0.011 to 0.040 g/L/day, and lipid accumulation, which ranged from 0.22 to 3.39 mg/L/day. Additionally, the lipid content varied between 5.04 % and 14.75 %. Interestingly, changes in CO2 concentration, ranging from 0.04 % to 40 %, significantly influenced the composition of fatty acids, leading to elevated levels of C16–C18 fatty acids. Nevertheless, these alterations had a minimal impact on the overall quality of biodiesel. The estimated fuel characteristics of the produced biodiesel complied with global specifications for biodiesel, providing better oxidative stability (≥6 h), high heating value (≥39 MJ/kg), and cetane number (≥47). Therefore, this study emphasizes sustainable CO2 capture and the potential of microalgae as a renewable source of economically viable biodiesel.

Converting neem seed-derived oil into biodiesel using zeolite ZSM-5 as an efficient catalyst via electrosynthesis procedure: Optimization of operating variables using response surface methodology (RSM)

Biodiesel has been contemplated as the best alternative to diesel fuel, owing to its distinctive qualities which cause environmental preservation. The purpose of this research is to convert Neem Seed-Derived Oil (NSDO) into biodiesel through zeolite ZSM-5 as a heterogeneous acid catalyst, by applying an electrosynthesis technique. The response surface methodology according to central composite design (RSM-CCD) was exerted to optimize the process conditions and obtain a reliable model. Based on the RSM-CCD technique, the parametric range for optimization study was as follows: voltage of 10–40 V, time of 0.5–1.5 h, Me/NSDO of 10–30 molar ratio, and catalyst amount of 2–6 wt%. The best yield of produced biodiesel, based on the design of the experiment's model predictions, was 85.96%, and based on the experimental observations, was obtained at 86.03%, which indicates a very high adaptation of experimental design with experimental data. The optimal operating conditions, to get the best process efficiency, were as follows: voltage of 25 V, time of 1 h, Me/NSDO (Methanol to Neem Seed Derived Oil) molar ratio of 20:1, and catalyst amount of 6 wt%. The reaction yielded satisfactory results due to the catalyst's exceptional efficiency, which also demonstrated impressive performance and reusability, exhibiting only a 14% reduction in yield after five successive cycles. The catalyst was characterized by analyses, and moreover the produced biodiesel was analyzed by qualitative and quantitative analyses of FT-IR (Fourier Transform Infrared Spectroscopy) and GC-FID (Gas Chromatography with Flame Ionization Detector). As well as, to investigate the produced biodiesel quality, physicochemical analyzes were used, according to ASTM (American Society for Testing and Materials) standards, and the measured results were completely consistent with the quality characteristics of diesel fuel.

Production of high quality biodiesel from sunflower soapstock acid oil as novel feedstock: Catalyzed by immobilized pancreatic lipase

AbstractEdible refined oils, which are utilized as raw materials in biodiesel production, have been replaced by by‐products (acid oil, fatty acid, deodorized distillate, and soapstock distillates) obtained from the vegetable oil refining industry, in recent years. This study aims to investigate the production of high quality biodiesel fuel in accordance with the standards (TS EN and ASTM) from sunflower soapstock acid oil. This feedstock was donated by an oil factory in the Thrace region, Turkey. Esterification reaction was performed by immobilized enzyme. For this, immobilization was carried out by covalent binding of pancreatic lipase in glutaraldehyde activated chitosan and optimum immobilization conditions were determined. The activity of the immobilized lipase and the retained activity were found to be 65.69 U/μg and 61.8%, respectively (pH: 7.5, 37°C). The Km (Michealis constant) and Vmax (maximum velocity of an enzymatically catalyzed reaction) values of the immobilized enzyme were found to be 5.1 mmol/L and 48.6 U/min/mg protein, respectively. The immobilized enzyme was employed as a biocatalyst for esterification of sunflower soapstock acid oil. Notably, an impressive yield of 75.6% was attained under the conditions of a 1:5 molar ratio of soapstock acid oil to methanol, with 10 wt% immobilized lipase as the catalyst, and a reaction temperature of 45°C for 36 h. The resulting biodiesel exhibits fuel characteristics that meet the standards outlined in TS EN 14214:2012 + A2 and ASTM D6751‐02.

Indigenous microalgae strains characterization for a sustainable biodiesel production.

Microalgae have been widely recognized as a promising feedstock for sustainable biofuels production to tackle global warming and pollution issues related to fossil fuels uses. This study identified and analyzed indigenous microalgae strains for biodiesel production, specifically Chlorella vulgaris and Coelastrella thermophila var. globulina, from two distinct locations in Algeria. Molecular identification confirmed their identity, and the microalgae exhibited notable growth characteristics. Local Chlorella vulgaris and Coelastrella thermophila var. globulina showed good growth and high biomass yield, compared to Chlorella vulgaris CCAP211/11B reaching a weight of 1.48 gL-1 , 1.95 gL-1 , and 2.10 gL-1 , respectively. Lipids content of local Chlorella vulgaris, Coelastrella thermophila var. globulina, and Chlorella vulgaris CCAP211/11B, were found to be 31.39±3.3%, 17±2.26%, and 19±0.64%, respectively. Chlorella vulgaris stood out as a candidate for biodiesel production due to its equilibrium between SFA and PUFA (43.24% and 45.27%). FAs are predominated by SFA and MUFA for Coelastrella thermophila var. globulina with value of 81.49% (SFA+MUFA). Predicted biodiesel qualities comply with ASTM6751 and EN14214 standards. Studied microalgae have therefore a promising potential for biodiesel production. However, optimising cultivation conditions is necessary to enhance biomass and lipids yield at a large scale.

Effects of polyethylene terephthalate microplastics on cell growth, intracellular products and oxidative stress of Scenedesmus sp.

Polyethylene terephthalate (PET) has been widely utilized in the synthesis of textile materials and packaging of foods and beverages. In recent years, it has been commonly detected in the form of microplastics (MPs) in wastewater. However, the effects of PET MPs on microalgal intracellular products and their interrelationships have been poorly investigated. In this study, the microalgae Scenedesmus sp. Strain H-1 was exposed to PET MPs to explore their effects on the growth, intracellular products (such as lipids, carbohydrates, and proteins), and antioxidative defense systems of Scenedesmus sp. The results demonstrated that PET MPs significantly reduced Scenedesmus sp. cell growth, with a maximum inhibition rate of 38.25% in the 500 mg L−1 treatment group. PET MPs had negative effects on glucose and nitrate utilization rates and reduced intracellular carbohydrates, intracellular proteins, and photosynthetic pigments. Surprisingly, PET MPs reduced acetyl-CoA carboxylase activity but induced lipid accumulation in microalgae. In addition, PET MPs significantly decreased the essential linoleic acid concentration and increased the palmitic acid content, resulting in reduced biodiesel quality. PET MPs induced the production of reactive oxygen species and malondialdehyde as well as the activities of superoxide dismutase and catalase. The results of the PCA indicated that the response mechanism of Scenedesmus sp. to PET MPs exposure was synergistic. This study provides fundamental data on the impact of MPs on the intracellular products of microalgae.

Development of a fast GC-response factor method to quantify total FAMEs in biodiesel from various fatty acid sources

Biodiesel is a renewable energy source that can be employed as an alternative fuel to fossil diesel. Monitoring samples in terms of fatty acid methyl esters (FAMEs) content using gas chromatography (GC) is a useful way to evaluate the quality of biodiesel produced. Fast GC can be used to reduce the time of analysis and consequently the costs, even though the equipment required for this may be expensive. Therefore, we developed and validated a Fast GC-response factor (Fast-GCRF) methodology using a low-priced nonpolar column, flame ionization detection (FID) and a standard chromatograph usually destined for conventional GC separations. The method was validated and applied to the quantification of FAMEs produced from various raw materials (soybean, cottonseed, canola, coconut, palm, sesame, sunflower, castor, corn, macauba, almond, peanut, chia seeds, residual frying oils, and chicken fat), being both selective and robust even when subjected to changes in sample preparation. The Fast GCRF method presented respective maximum relative standard deviation (RSD) values for instrumental precision, repeatability, and intermediate precision of 2.3 %, 3.6 %, and 2.8 %. When compared to conventional GC methodologies, accurate results with high degrees of agreement were obtained using the Fast-GCRF method, within an at least four times shorter analysis time.