Microalgae Oil Research Articles

Simulation of microalgae oil spray characteristics for mechanical fuel injection and CRDI systems

Simulation of microalgae oil spray characteristics for mechanical fuel injection and CRDI systems

A comparative study of in vitro gastrointestinal digestion of three strategic edible oils.

Three strategic edible oils, that is, olive oil, microalgae oil, and shea butter, with a significantly different composition of fatty acids (FA), have been studied in a static in vitro digestion model to evaluate the rate of hydrolysis, bioaccessibility, and micellar phases formed in the process. Lipid composition of each phase and how the lipids are distributed in the different phases have been obtained using this in vitro digestion model. We demonstrate that the composition in FA and the physical properties of the oil are the key factors determining the distribution of lipids in the different phases. The fastest rate of hydrolysis was observed for olive oil and the highest triacylglycerol conversion was attained for shea butter. In contrast, the most abundant precipitate phase was obtained for shea butter, which also produces the highest co-crystallization of cholesterol among the three edible oils studied. This study reveals that digestibility of edible oils is directly related with the initial rate of hydrolysis.

Technoeconomic Evaluation of Microalgae Oil Production: Effect of Cell Disruption Method

Microalgae have a high capacity to capture CO2. Additionally, biomass contains lipids that can be used to produce biofuels, biolubricants, and other compounds of commercial interest. This study analyzed various scenarios for microalgae lipid production by simulation. These scenarios include cultivation in raceway ponds, primary harvest with three flocculants, secondary harvest with pressure filter (and drying if necessary), and three different technologies for the cell disruption step, which facilitates lipid extraction. The impact on energy consumption and production cost was analyzed. Both energy consumption and operating cost are higher in the scenarios that consider bead milling (8.79–8.88 kWh/kg and USD 41.06–41.41/kg), followed by those that consider high-pressure homogenization (HPH, 5.39–5.46 kWh/kg and USD 34.26–34.71/kg). For the scenarios that consider pressing, the energy consumption is 5.80–5.88 kWh/kg and the operating cost is USD 27.27–27.88/kg. The consumption of CO2 in scenarios that consider pressing have a greater capture (11.23 kg of CO2/kg of lipids). Meanwhile, scenarios that consider HPH are the lowest consumers of fresh water (5.3 m3 of water/kg of lipids). This study allowed us to develop a base of multiple comparative scenarios, evaluate different aspects involved in Chlorella vulgaris lipid production, and determine the impact of various technologies in the cell disruption stage.

RETRACTED: Optimization of combustion, performance, and emission characteristics of a dual-fuel diesel engine powered with microalgae-based biodiesel/diesel blends and oxyhydrogen

• Diesel engine was powered with ternary blends of biodiesel-diesel-oxyhydrogen. • Third-generation biodiesel was synthesized from biomass of Azolla Pinnata . • A low-cost device-31 plates generator generated oxyhydrogen gas. • Oxyhydrogen addition improved engine performance and lowered emissions. • Box-Behnken design coupled with desirability approach used for optimization. The current study explores and improves the effects of engine load, injection time, and oxyhydrogen fuel flow rate on the combustion and emissions characteristics of a diesel engine. Experiment with the combustion and exhaust characteristics of a medium-sized diesel engine working in tri-fuel mode using microalgae oil methyl ester-diesel blends as injected fuel and an oxyhydrogen gas combination as inducted fuel. The Box-Behnken design (BBD) was used to reduce the number of testing. The parameters and proposed attributes were calculated utilizing response surface techniques and BBD-generated quadratic models. The response surface analysis displayed the patterns of input interactions on the output using surface diagrams. The desirability-based optimization revealed the optimal engine operating parameters as 22.92° crank angles advance, 76% engine load, and 0.92 L per minute oxyhydrogen flow rate. At these optimized operating ranges, the performance and combustion output of the study was 30.8 % brake thermal efficiency (BTE), 0.3 kg/kWh brake specific fuel consumption (BSFC), and 65.6 bar peak cylinder pressure (PCP). On the emission front, the CO emission was 0.0107%, UHC was 26 ppm, and NO x was 853 ppm. The optimized values were validated through experimental testing, and all the results were within 7% of the model-predicted output. The addition of oxyhydrogen significantly improved the combustion of an algal biodiesel-diesel-oxyhydrogen-powered diesel engine in terms of fuel efficiency and fuel consumption and lower carbon-based emission levels except for nitrogen oxide emissions.

Biodiesel Production through Acid Catalyst In Situ Reactive Extraction of Chlorella vulgaris Foamate

A method of biodiesel production from the freshwater microalgae Chlorella vulgaris based on the conversion of the dewatered algal biomass from a foam column (“foamate”) was investigated. The foam column collected and concentrated the microalgae. The foam was generated by passing air through a pool of algae, to which a collector/surfactant cetyltrimethylammonium bromide (CTAB) had been added. To produce biodiesel, the resultant “foamate” was esterified in situ using sulfuric acid and methanol. The effect of reaction temperature (30–70 °C), reaction time (30–120 min) and methanol/oil molar ratio (100–1000), were examined in a single-stage extraction–transesterification experiment on biodiesel yield at concentration of the catalyst H2SO4/oil molar ratio of (8.5/1). The thermodynamics and kinetics of transesterification of the microalgae oil were also investigated. The maximum biodiesel yield (96 ± 0.2%) was obtained at a reaction temperature of 70 °C, a reaction time of 90 min and methanol/oil molar ratio of 1000/1. Reaction kinetic parameters were determined that fitted the experimental data at all temperatures. A reversible reaction with first order forward and second order backward kinetics were found to be a good match for the experimental results. The kinetic model fitted experiments well under various temperatures and methanol/oil mole ratios. Under the most suitable conditions of reaction temperature, reaction time and methanol/oil molar ratio, the apparent activation energy was found to be 18.7 kJ/mol and pre-exponential factor 51.4 min−1. The activation entropy (ΔS), change in Gibbs free energy (ΔG) and variation in activation enthalpy (ΔH) revealed that the transesterification reaction is endergonic and unspontaneous, while the endothermic nature of the reaction was confirmed by the positive value (16.6 kJ/mol) of the ΔH. The thermodynamic information and kinetic model reported here will provide valuable insight into the understanding of the in situ transesterification process from algae foamate to biodiesel.

RETRACTED: Multi-attribute optimization of sustainable aviation fuel production-process from microalgae source

The aviation sector has been one of the most significant contributors to greenhouse gas (GHG) emissions; there is an urgent need to transition from traditional fossil-based jet fuel to sustainable aviation fuel to meet net-zero targets by 2030. The use of renewable aviation fuel may be regarded as the most effective option for reducing GHG emissions in the aviation sector while allowing for long-term growth. In this study, the microalgae oil was transformed to develop hydrocarbons with the boiling point range of jet fuel. Following the transesterification of algal oil fatty acids to algal oil methyl ester, fractional distillation was carried out. The Box-Behnken technique was used to design experiments for efficient resource utilization by minimizing the number of tests during transesterification. The quantitative relationship function between input (molar ratio of methanol to oil, catalyst concentration, and temperature) and % yield of methyl ester as an output of the process was developed using analysis of variance (ANOVA). The ANFIS (adaptive neuro-fuzzy inference system) was utilized to develop a prognostic model with good prediction effectiveness. MORSM (multi-objective response surface methodology) was also used to build a prediction model using correlations. A set of statistical indicators and Theil's U2 were used to examine the prediction efficacy and model uncertainty of ANFIS and MORSM. On both statistical indices and Theil's U2, the ANFIS-based model outperformed. To get the best results, the desirability approach was used to improve operating parameters. According to the desirability approach, the best operating parameters were catalyst concentration at 2.09%, methanol to oil ratio at 9.17%, and temperature at 60.49 °C, which resulted in the greatest yield of 91%.

Application of Microalgae Biomass for Biodiesel Fuel Production

Recently, there has been a growing interest in the use of new types of cheaper raw materials for biodiesel production. There are many prospects for microalgae, which do not compete for land with conventional biodiesel raw materials, are characterized by rapid reproduction and high biomass accumulation, and under certain conditions, some are able to accumulate a large amount of oil. A number of studies have been conducted on the extraction of oil from microalgae cells and transesterification with various acyl receptors. This paper provides an overview of the results of research on microalgal biomass preparation and oil extraction. Indicators of the quality of the oil are presented and its suitability for biodiesel synthesis is analyzed. The homogeneous and heterogeneous catalysts used for oil transesterification are described and the optimal conditions of the process when using various alcohols as acyl receptors are presented. Much attention is paid to the parameters affecting the transesterification efficiency and biodiesel yield. The physical and chemical, and operational and environmental properties of biodiesel obtained from algae oil are analyzed. The evaluation of the economic efficiency of biodiesel synthesis is also presented.

A hydrodynamic cavitation-assisted system for optimization of biodiesel production from green microalgae oil using a genetic algorithm and response surface methodology approach.

In the present research work, the effect of operating parameters such as molar ratio (3:1-7:1), catalyst concentration (0.5-1.5%), reaction time (5-25min), and operating pressure (0-4bar) on the rate of biodiesel conversion percentage for the transesterification reaction using hydrodynamic cavitation (HC) has been studied. Response surface methodology (RSM) and genetic algorithms (GA) were used to find the best condition. The best conditions for biodiesel generation were a molar ratio of 6.5:1, a catalyst concentration of 1.301 wt.%, a reaction period of 11.5min, and operating pressure of 3.6bar. The maximum yield of biodiesel obtained under optimal conditions was 97.3%. The reaction time for biodiesel produced by HC under similar conditions as the conventional technique was reduced by 85%. The HC approach is preferable to the conventional method due to its shorter processing time.

Lipid Constituents of Diatoms (Halamphora) as Components for Production of Lipid Nanoparticles.

Lipid nanocarriers smaller than 200 nm may be used as pharmaceutical/cosmetic raw materials as they are able to penetrate the skin. The nanostructured lipid carriers (NLCs) based on microalgae oil (Schizochytrium) and lipids extracted from diatoms (Halamphora cf. salinicola (strain SZCZM1454A)) were produced by the HSH (high shear homogenization) method. Fatty acid profile of crude oil from diatoms indicated the presence of palmitoleic, palmitic, stearic acid, oleic and myristic acids as the most common fatty acids in the strain investigated. The quantitative composition and the synthesis condition of NLC dispersions were optimized by using the full factorial designs. The physicochemical parameters of the obtained lipid nanocarriers were characterized by SEM, DSC and XRD measurements and the fraction with the optimum parameters (size below 200 nm, polydispersity index not exceeding 0.2 and zeta potential higher than +45 mV) was selected for further study. The positive charge of the obtained lipid nanoparticles is beneficial as permits electrostatic bonding with the negatively charged skin surface. As follows from stability tests, the NLCs obtained could be stored at room temperature.

Production of Biodiesel from Mixed Castor Seed and Microalgae Oils: Optimization of the Production and Fuel Quality Assessment

The diminishing reserves and environmental consequences of the fossil fuel-based petrodiesel necessitate the exploration of an alternative fuel with better quality and minimum environmental impacts. The study explores the optimization of biodiesel production from nonfood and locally available mixed feedstocks as an effective and a sustainable approach to solve the insufficiency and high costs of single oil feedstock. The selection of suitable oil feedstocks and optimization of process variables are the prime issues for cost-effective industrial scale production of biodiesel from mixed feedstocks toward the industrial scale production of biodiesel. The objective of this study was to optimize process variables for the alkaline transesterification of mixed castor seed and microalgae oils to optimize the yield of biodiesel. Oils were extracted from dried microalgae (Chlorella vulgaris) biomass and castor seed kernel using methanol. The oils were purified, characterized, mixed in a 1 : 1 ratio, and converted to biodiesel. The transesterification experiments designed according to the central composite design (CCD) were used to optimize the yield of biodiesel through the response surface methodology (RSM). Experimental results were analyzed by response surface regression to produce a model for predicting biodiesel yield. Model significance, fitness, the effect of significant variables, and interactions between the variables on the yield of biodiesel were studied through the analysis of variance (ANOVA). The optimization of transesterification process variables revealed that the catalyst concentration of 1.23% (w/w), ethanol to mixed oil ratio of 5.94 : 1 (v/v), and reaction temperature of 51.0°C were the optimum conditions to achieve an optimum biodiesel yield of 92.88%. Validation experiments conducted under the optimum conditions resulted in the biodiesel yield of 92.36%, which is very close to the model predicted value. Various standard methods were used to characterize the biodiesel produced under optimum conditions, and it was found compatible with ASTM 751 and EN14214 biodiesel standards.

Lipase catalysis: an environmentally friendly production for polyol esters (biolubricant) from microalgae oil

ABSTRACT This study aims to investigate the optimized lipase-catalysed esterification reaction from novel feedstock microalgae (Chlorella protothecoides) oil-free fatty acids (FFAs) for biolubricant (Trimethylolpropane (TMP)-triesters) synthesis. FFAs were obtained from microalgae oil by enzymatic hydrolysis. Response surface methodology (RSM) with the central composite design was performed to investigate the effect of experimental factors (lipase amount, TMP/FFAs molar ratio, reaction temperature) on the FFAs conversion and also investigated to resolve the optimum design points. After the experimental studies, the highest FFAs conversion of 93% with 92% triester and 8% mono, di esters contents were found when the lipase amount was 5.5%. TMP/FFAs molar ratio was 0.33 and the reaction temperature value was 60°C. The model fitted with the experimental values with R 2 = 0.97. It was also supported by gas chromatography and FTIR analyses that the product obtained was a lubricant.

The effect of 3D structure preparation method on lipase/3DMGO biocatalytic parameters and catalytic performance in transesterification of microalgae bio-oil

Nano-biocatalysts, based on Rhizopus oryzae lipase (ROL) immobilized on 3D superparamagnetic graphene oxide (3DMGO) were prepared in two methods and used for the conversion of Chlorella vulgaris oil to biodiesel. The 3D graphene oxide hydrogel was synthetized using two different cross-linking agents, p-phenylene diamine (PPD) and ethylene diamine tetra acetic acid (EDTA), and then magnetized by insitu co-participation of Fe3O4. A modified BG-11 medium was used for cultivation of this microalgae to increase the total biomass lipid (up to 35 wt%). The kinetics parameters, enzyme loading percentage, thermal stability, and storage stability of ROL, ROL/3DMGO-EDTA, and ROL/3DMGO-PPD were evaluated. The biodiesel production yields in the presence of ROL, ROL/3DMGO-PPD, and ROL/3DMGO-EDTA were 75.04%, 74.25%, and 72.12%, respectively. The reusability tests confirmed that the ROL/3DMGO-EDTA had better performance. Therefore, 3D graphene oxide nanostructures can be introduced as a suitable option for enzyme immobilization in the biodiesel production from microalgae oil.

A new urea adducts method for PUFA concentration using green food grade solvents and avoiding ethyl carbamate formation

This study aimed to selectively enrich stearidonic acid (SDA) together with γ-linolenic acid (GLA) in Echium plantagineum oil by urea complexation. The complexation process at room temperature was carried out replacing common organic solvents, such as hexane and ethanol, by alternative compounds, included in Green Solvent and Food Grade categories, adapting this process towards the principles of Green Chemistry. This substitution was also intended to avoid the generation of the toxic compound ethyl carbamate. Among all the solvents studied, the mixture propionic acid and α-pinene provided the best results, leading to a final product comprised of ∼99% of PUFA, with ∼45% SDA (∼14% in the original oil), and without apparition of ethyl carbamate. The procedure was tested on other raw materials (salmon and microalgae oils). The solvent was efficiently recuperated from the liquid phase (∼87% recovery) and reutilized once with almost identical results.

Investigation of the pure use of microalg oil in diesel engines

The effects of mixing pure vegetable oils with diesel fuels and using them in diesel engines were explored in this study. Due to its great production, Chorella protactes, a microalgae species, was employed as a vegetable oil. First, pure microalgae oil was combined with 5% (DSYK-5) and 10% (DSYK-10) diesel reference fuel (RDF) by volume for this experiment. The resulting blended fuels and diesel reference fuel were put to the test in a four-cylinder, four-stroke diesel engine at 1500 rpm and various loads. With the use of pure oil, the results showed a 4.64 percent rise in specific fuel consumption (SFC). CO emissions reduced by 9.05 percent on average when DSYK-5 fuel was used, while CO emissions increased when DSYK-10 fuel was used. HC emissions reduced by 4.6 percent on average when blended fuels were used, whereas NOx emissions increased by 3.13 percent on average. CO2 emissions were comparable to RDF fuel when DSYK-5 fuel was used. When comparing RDF fuel to DSYK-10 fuel, fewer CO2 emissions were found. Average gas temperatures, cumulative heat releases, and cylinder pressure values all reduced as the pure oil ratio in the mixture ratio increased.

Comprehensive Analysis of Fatty Acid and Oxylipin Patterns in n3-PUFA Supplements.

Supplementing long-chain omega-3 polyunsaturated fatty acids (n3-PUFA) improves health. We characterized the pattern of total and non-esterified oxylipins and fatty acids in n3 supplements made of fish, krill, or micro-algae oil by LC-MS. All supplements contained the declared amount of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); however, their content per capsule and the concentration of other fatty acids varied strongly. Krill oil contained the highest total n3 oxylipin concentration (6000 nmol/g) and the highest degree of oxidation (EPA 0.7%; DHA 1.3%), while micro-algae oil (Schizochytrium sp.) showed the lowest oxidation (<0.09%). These oils contain specifically high amounts of the terminal hydroxylation product of EPA (20-HEPE, 300 nmol/g) and DHA (22-HDHA, 200 nmol/g), which can serve as an authenticity marker for micro-algae oil. Refined micro-algae and fish oil were characterized by NEFA levels of ≤0.1%. Overall, the oxylipin and fatty acid pattern allows gaining new insights into the origin and quality of n3-PUFA oils in supplements.

Effects of light intensity and photoperiod on growth, lipid accumulation and fatty acid composition of Desmodesmus subspicatus LC172266 under photoautotrophic cultivation

Microalgae oil accumulation in their natural growing states hardly reaches the quantities needed to replace fossil-derived diesel. Therefore, for algae to be used as biofuel feedstock, their growths are manipulated with the aim of achieving high cell density and high lipid accumulation. Two major factors affecting microalgal biomass and lipid productivity are light intensity and photoperiod. In the present study, Desmodesmus subspicatus was grown photoautotrophically under varying light intensities and photoperiods with a view to assessing the growth, lipid accumulation potential and fatty acid composition. Whereas the optimal light intensity for biomass production of the microalga was 5000 lx, that for lipid productivity was 3500 lx. At 5000 lx and 18: 6 h light/dark cycle, biomass yield, lipid content and lipid productivity were highest, at values of 1.92 ± 0.03 g/L, 53% and 118.80 ± 2.04 mgL-1day -1 respectively. The major fatty acid of the alga was oleic acid irrespective of light changes. The quantities of lipid accumulated and the properties of the fatty acid methyl esters showed that Desmodesmus subspicatus LC172266 is an ideal feedstock for biodiesel production.

Performance, combustion and emission characteristics of the CI engine fueled with Botryococcus braunii microalgae with addition of TiO2 nanoparticle

Production of biofuels from the green synthesis considered to be the promising source of the energy to replace the conventional fuels. Further the usage of the biofuels in the optimized ratio will effectively reduce the environmental concerns and the reduce the greenhouse gas emission. In this study, the impact of the Botryococcus braunii microalgae along with the diesel was examined. From the previous work it is understood that, usage of the Botryococcus braunii in the diesel affects the combustion and performance characteristics. To avoid the shortcomings, the nanoparticles TiO2 (50 ppm) were dispersed in the biodiesel blends by sonication method. The test blends such as D100 (100% diesel), B100 (neat microalgae oil), B10 (20% microalgae + 80% diesel), B10T (20% microalgae + 80% diesel), B30 (30% microalgae + 70% diesel) and B30 (30% microalgae + 70% diesel) were tested at engine loads of 0%, 25%, 50%, 75% and 100%. Individual blends were tested for brake thermal efficiency, brake specific fuel consumption, indicated thermal efficient, cylinder pressure and emission of NO, HC, CO and CO2. Based on the findings, addition of the microalgae blends with the nanoparticles enhances the BTE by 5% and 3% for BT20 and BT30, respectively, compared to neat diesel. Further, the BSFC was precisely reduced for B30 compared to D100 and B20 due to the viscosity of the blends. The role of the mixed fuel addition along with nanoparticles increases the cylinder pressure and heat release rate. With regard to emission, the CO, HC and CO2 reported significant drop in the emissions. However, NOx emissions remain to be high despite the engine speed for the blends B30.

Macular pigment-enriched oil production from genome-edited microalgae

BackgroundThe photosynthetic microorganism Chlamydomonas reinhardtii has been approved as generally recognized as safe (GRAS) recently, this can excessively produce carotenoid pigments and fatty acids. Zeaxanthin epoxidase (ZEP), which converts zeaxanthin to violaxanthin, and ADP-glucose pyrophosphorylase (AGP). These are key regulating genes for the xanthophyll and starch pathways in C. reinhardtii respectively. In this study, to produce macular pigment-enriched microalgal oil, we attempted to edit the AGP gene as an additional knock-out target in the zep mutant as a parental strain.ResultsUsing a sequential CRISPR-Cas9 RNP-mediated knock-out method, we generated double knock-out mutants (dZAs), in which both the ZEP and AGP genes were deleted. In dZA1, lutein (2.93 ± 0.22 mg g−1 DCW: dried cell weight), zeaxanthin (3.12 ± 0.30 mg g−1 DCW), and lipids (450.09 ± 25.48 mg g−1 DCW) were highly accumulated in N-deprivation condition. Optimization of the culture medium and process made it possible to produce pigments and oil via one-step cultivation. This optimization process enabled dZAs to achieve 81% higher oil productivity along with similar macular pigment productivity, than the conventional two-step process. The hexane/isopropanol extraction method was developed for the use of macular pigment-enriched microalgal oil for food. As a result, 196 ± 20.1 mg g−1 DCW of edible microalgal oil containing 8.42 ± 0.92 mg g−1 lutein of oil and 7.69 ± 1.03 mg g−1 zeaxanthin of oil was produced.ConclusionOur research showed that lipids and pigments are simultaneously induced in the dZA strain. Since dZAs are generated by introducing pre-assembled sgRNA and Cas9-protein into cells, antibiotic resistance genes or selective markers are not inserted into the genome of dZA, which is advantageous for applying dZA mutant to food. Therefore, the enriched macular pigment oil extracted from improved strains (dZAs) can be further applied to various food products and nutraceuticals.

Microalgae Biomass as a New Potential Source of Sustainable Green Lubricants.

Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. However, production, usage and disposal of these lubricants have significant impact on environment and health. Hence, there is a growing pressure to reduce demand of this sort of lubricants, which has fostered development and use of green lubricants, as vegetable oil-based lubricants (biolubricants). Despite the ecological benefits of producing/using biolubricants, availability of the required raw materials and agricultural land to create a reliable chain supply is still far from being established. Recently, biomass from some microalgae species has attracted attention due to their capacity to produce high-value lipids/oils for potential lubricants production. Thus, this multidisciplinary work reviews the main chemical-physical characteristics of lubricants and the main attempts and progress on microalgae biomass production for developing oils with pertinent lubricating properties. In addition, potential microalgae strains and chemical modifications to their oils to produce lubricants for different industrial applications are identified. Finally, a guide for microalgae oil selection based on its chemical composition for specific lubricant applications is provided.

ANALYSIS OF ANTIMICROBIAL, ANTIBIOFILM, AND HEALING ACTIVITY OF LIPID NANOCARRIERS BASED ON TUCUMAN BUTTER (Astrocaryum vulgare), FIXED OILS FROM MICROALGAE Chlorella homosphaera AND FROM UVA SEED Vitis vinifera

Therapeutic alternatives of natural origin have been arousing the interest of large research centers that are looking for new bioactive molecules to treat numerous diseases in the context of public health. Among them, infectious diseases, which present antimicrobial resistance, deserve attention. The present study aimed to evaluate the antimicrobial activity of lipid nanocarriers (CLN), as well as the healing activity, arising from the association of tucumã butter with grape seed oil and another one containing microalgae oil. Two formulations were prepared using the high-speed homogenization technique, which was evaluated for antimicrobial action for 10 strains of great clinical importance, including a multiresistant and healing activity. The formulation with Chlorella homosphaera oil showed growth inhibition for the 10 strains tested, in addition to antibiofilm activity for 8 strains, bactericidal action for 3 of 3 isolates, and satisfactory healing action in 48 hours.