Biodiesel Application Research Articles

Experimental and kinetic modeling study of methyl heptanoate low-temperature oxidation in a jet-stirred reactor

Methyl heptanoate (MHP) is a potential surrogate component for fatty acid methyl esters found in biodiesel. The carbon chain length of MHP is long enough to enable low temperature (low-T) reactivity and negative temperature coefficient oxidation behavior during the combustion experiments, similar to the real biodiesel fuels. This paper investigated the low-T oxidation of MHP at 780 Torr and equivalence ratios of 0.5, 1.0 and 1.5 in a jet-stirred reactor. Detailed speciation profiles of fuel, intermediates and products were obtained using synchrotron vacuum ultraviolet photoionization mass spectrometry. A comprehensive kinetic model with 779 species and 3594 reactions was developed and validated against the new experimental data. Model analysis indicated that the dominant reaction pathways for MHP consumption were H-abstraction reactions by radicals of OH, HO2 to produce MHP radicals under all experimental conditions. In this low-T oxidation region, O2 addition reactions were responsible for the consumption of MHP radicals. The formation pathways of unsaturated methyl esters were strongly related to the decomposition of cyclic ethers. Furthermore, the formations of CH3OOH and C2H5OOH were closely linked to the reactions of CH3O2 and C2H5O2 as well as the radicals of CH2O and HO2. This work provides detailed information relevant to low-T biodiesel oxidation chemistry and guidance for the application of biodiesel in internal combustion engines.

Optimizing biodiesel production from abundant waste oils through empirical method and grey wolf optimizer

The failure of classical techniques and algorithms have triggered researchers to search for stochastic tools capably of exploring the search space with constant convergence speed. Grey wolf optimizer (GWO) is a moderately novel stochastic algorithm with only a few parameters to regulate that can be easily employed for global optimization. For the first time, this study explored GWO to model biodiesel yield. It is worthy to note that, kerosene (KS) popularly known as paraffin oil has gained global attention in the aviation and biodiesel industries to improve cold flow properties and can be mixed with diesel in different proportions. Therefore, in this study, (1) Response Surface Methodology (RSM) and GWO were explored to model the waste sunflower oil methyl ester (WSOME)/biodiesel (BD) production from waste sunflower oil (WSO) and (2) Least square regression method was accosted to correlate the density of (0%KS + 100%BD), (5PKS + 95%BD), (20%KS + 80% BD), (50%KS + 50%BD) and (100%KS + BD) blends. The yield of WSOME (96.70%) was optimum at the methanol/oil molar ratio of 5.99/1, catalyst amount of 1.1 wt.% and reaction time of 77.6 min. The GWO model displayed a higher coefficient of determination, and a lower value of root mean squared errors compared to the RSM model. GWO predicted values, as compared to RSM, predicted yield indicates its reliability and usefulness for prediction without trial and error of conventional experimentation. The fuel properties concurred with the ranges of the ASTMD6751 and EN 14214 specifications. The quadratic relation with high regression coefficient (R2) was detected for the densities of (0%KS+100%BD) and (20%KS +80% BD) while the linear was found suitable for the densities of (5KS + 95%BD), (50%KS +50BD) and (100%KS+0%BD). The model and correlations can find application in biodiesel and aviation industries.

Role of C/N ratio on microalgae growth in mixotrophy and incorporation of titanium nanoparticles for cell flocculation and lipid enhancement in economical biodiesel application.

Present study aimed to evaluate the influence of carbon/nitrogen ratio (C/N) on mixotrophic growth of microalgae and role of nanomaterial in cell recovery and lipid improvement. In this study, three microalgae species were isolated, screened from local freshwater body for lipid assimilation. The microalgae were identified as Chlorococcum sp., Scenedesmus sp., and Euglena sp. Mixotrophic cultivation of each microalgae strain using various organic carbon sources was preferred in contrast with photoautotrophic mode. Sucrose represented as the preeminent source for enhancing the microalgae biomass of 3.5g/L and lipid content of 58.35%, which was a significant improvement as compared to control. Later, response surface methodology-central composite design (RSM-CCD), tool was employed to optimize the C/N ratio and demonstrated the maximum biomass production of 5.02g/L along with the increased lipid content of 60.34%. Ti nanoparticles (Ti nps) were added to the culture for lipid enhancement in the stationary phase and biomass removal was performed by nanoparticle (np)-mediated flocculation technique. Optimized concentration of 15ppm Ti nps determined the cell harvesting efficacy of 82.46% during 45min of sedimentation time and 1.23-fold lipid enhancement was reported. Extracted lipid was converted to fatty acid methyl esters (FAME) by the process of transesterification and analyzed by gas chromatography-mass spectrometry (GC-MS). Characterization of FAME revealed the presence of 56.31% of saturated fatty acid (SFA) and 29.06% unsaturated fatty acids (UFA) that could be processed towards sustainable biodiesel production. Hence, our results suggested that integration of mixotrophic cultivation and Ti nps emerged as a new cost-effective approach for biomass and lipid enhancement in microalgae Chlorococcum sp.

Spirulina sp. as a Bioremediation Agent for Aquaculture Wastewater: Production of High Added Value Compounds and Estimation of Theoretical Biodiesel

The rapid development of large-scale aquaculture leads to wastewater accumulation, increasing environmental problems. Microalga cultivation is a potential biotechnological alternative to treat aquaculture wastewater. While this microorganism consumes the wastewater nutrients, high added value biomass is produced. The role of Spirulina in aquaculture wastewater treatment is not fully elucidated in the literature. Thus, this study aimed to reuse and treat aquaculture wastewater by Spirulina sp. LEB 18 cultures. The microalga growth parameters, the biochemical composition of the biomass produced, and the Spirulina efficiency to nutrient removal from the aquaculture wastewater were evaluated. The assays were performed in closed photobioreactors (1 L) using 100% aquaculture wastewater (T-0) supplemented with 25 (T-25), 50 (T-50), and 75% (T-75) of the Zarrouk synthetic culture medium. The maximum biomass concentrations showed no statistical difference between the assays T-50 (1.02 g L−1), T-25 (1.10 g L−1), and control (1.05 g L−1). The biomass from the T-25 assay showed the highest concentrations of protein (65.73%), phycocyanin (16.60 mg/mL), polyunsaturated fatty acid (38.20%), and γ-linolenico (23.29%). Besides that, the Spirulina sp. LEB 18 highest removal rate of sulfate (94.01%), phosphate (93.84%), bromine (96.77%), and COD (90.00%) was obtained from the T-25 assay. The biomass from T-25 and T-50 assays showed ideal properties for biodiesel application. The Spirulina sp. LEB 18 cultures using 100% aquaculture wastewater supplemented with 25% of Zarrouk culture medium was the best option for the aquaculture wastewater treatment, producing added value biomass and reducing production cost.

Synthesis of Nano ZnO: A Catalyst for N-formylation of Aromatic Amines and Biodiesel Application

Background: Zinc oxide nanoparticles prepared from an easy, eco-friendly and cost-effective green combustion technique using an extract of turmeric root has been an immense attractive nanomaterial that is used widely in light emitting display systems, piezoeletricity, electric conductivity, and biological applications. The prepared samples were characterized for their structural and morphological study using various analytical techniques. Results: Crystallite size was calculated by both XRD as well as UV-visible absorption measurements and Crystallite size was found to be 14-36 nm. An equation was developed with the aid of an effective mass model (Brus 1986) to calculate the size of the particle as a function of the peak absorbance wavelength. The energy bandgap of the synthesized sample calculated to be in the range of 4.74 - 5.0 eV by UV-Vis spectra confirms the quantum confinement. ZnO nanocatalyst is used for the synthesis of biodiesel from garcinia gummigutta seed oil has been studied. The environmental friendly procedure was carried for the formylation of amines under solvent-free reaction condition and simple work-up giving pure products with prompt recyclability behavior are the main features of the reaction. Conclusion: In this work, ZnO NPs were synthesised using turmeric root extract as a fuel via green combustion method. It is an environmentally friendly, easy as well as cost-effective method for the synthesis of nanoparticles. ZnO NPs were examined through various equipments such as PXRD, UV-Vis, FTIR, and SEM studies. XRD study show the hexagonal wurtzite structure. it is a good catalyst for the synthesis of biodiesel from the pongamiapinnata oil. It also serves as a catalyst for the Nformylation reactions, which involves the clean procedure under milder reaction conditions with an excellent yield of the desired products

Environment-Friendly Biodiesel/Diesel Blends for Improving the Exhaust Emission and Engine Performance to Reduce the Pollutants Emitted from Transportation Fleets

Biodiesel derived from biomass is a renewable source of fuel, and global application of biodiesel in the transport sector has rapidly expanded over the last decade. However, effort has been made to overcome its main shortcoming, i.e., efficiency and exhaust emission characteristics (NOx emissions) in unmodified diesel engines. Biodiesel combustion generally results in lower unburned hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM) in exhaust emissions compared to fossil diesel. In this study, various biodiesel blends (Chlorella vulgaris, Jatropha curcus, and Calophyllum inophyllum) were investigated for fuel characteristics, and engine performance with exhaust emission compared to diesel. Chlorella vulgaris, Jatropha curcus, and Calophyllum inophyllum biodiesel were synthesized by the acid–base transesterification approach in a microwave reactor and blended with conventional diesel fuel by volume. The fuel blends were denoted as MB10 (90% diesel + 10% microalgae biodiesel), MB20 (80% diesel + 20% microalgae biodiesel), JB10 (90% diesel + 10% jatropha biodiesel), JB20 (80% diesel + 20% jatropha biodiesel), PB10 (90% diesel + 10% polanga biodiesel) and PB20 (80% diesel + 20% polanga biodiesel). Experiments were performed using these fuel blends with a single-cylinder four-stroke diesel engine at different loads. It was shown in the results that, at rated load, thermal efficiency of the engine decreased from 34.6% with diesel to 34.1%, 33.7%, 34.1%, 34.0%, 33.9%, and 33.5% with MB10, MB20, JB10, JB20, PB10, and PB20 fuels, respectively. Unburned hydrocarbon, carbon monoxide and smoke emissions improved with third-generation fuels (MB10, MB20) in comparison to base diesel fuel and second-generation fuels (JB10, JB20, PB10 and PB20). Oxides of nitrogen emissions were slightly increased with both the third- and second-generation fuels as compared to the base diesel. The combustion behavior of microalgae biodiesel was also very close to diesel fuels. In the context of comparable engine performance, emissions, and combustion characteristics, along with biofuel production yield (per year per acre), microalgae biodiesel could have a great potential as a next-generation sustainable fuel in compression engine (CI) engines compared to jatropha and polanga biodiesel fuels.

Study of the Use of Hydrotalcite–Hydroxyapatite as Heterogeneous Catalysts for Application in Biodiesel Using By-Product as Raw Material

The materials hydrotalcite—HT, hydroxyapatite—HAp and hydrotalcite–hydroxyapatite—HT–HAp were synthesized using the co-precipitation method at constant pH (pH 10), in which first the materials of HT and HAp were synthesized and later a reaction mixture for the formation of HT–HAp material. The materials were characterized by X-ray diffraction (XRD), N2 adsorption and desorption, infrared spectral analysis (FT-IR), thermogravimetric analysis (TG) and morphology. The results indicated that the analysis by XRD confirmed that all materials (HT, HAp, and HT–HAp) presented the typical basal peaks of HT and HAp and that in the HT–HAp material it presented a better crystalline ordering. The analysis of specific surface area (BET) showed that the mixture of materials (HT–HAp) caused a loss of the specific area, indicating a possible interaction between the particles of both materials. The pore diameters showed mesoporosity. In addition, the materials HT, HAp and HT–HAp had their catalytic activity determined through transesterification reactions using different lipid raw materials (commercial soy oil and vegetable oil deodorization distillate-VODD) obtaining ethyl esters (biodiesel) as a product. The results for the raw material commercial soybean oil showed that the catalysts HT and HAp obtained incomplete reactions, that is, they presented low conversions in ethyl esters (about 39–65% in 6 h of reaction). On the other hand, the study of the influence of temperature on the calcination of the HT–HAp catalyst obtained high conversions in ethyl esters, about 98% for the catalyst calcined at 700 °C, under conditions of 45:1 ethanol/oil molar ratio, temperature of 70 °C, catalyst concentration of 5% and 6 h of reaction. With the transesterification of soybean oil as a comparative form, the catalyst in its best conditions was used to transesterify the VODD by-product. Which results of conversion into considerable ethyl esters were found (about 88%, in just 6 h of reaction), thus confirming that the chemical catalyst was able to form the main esters of fatty acids even using different lipid sources.

Synthesis and characterizations studies of ZnO and ZnO-SiO2 nanocomposite for biodiesel applications

This paper discusses with the synthesis of nanoparticles of ZnO and ZnO-SiO2 nanocomposite by sol–gel method. Characterisation studies are taken for each sample and compared with previous literatures. Therefore, the synthesized particles were characterized by FTIR, SEM, XRD & BET analysis to obtain chemical bonding, surface morphology, crystallinity and surface area of the particles respectively micrographs of ZnO nanoparticles show hexagonal shaped ZnO and ZnO-SiO2 nanocomposite revealed an increase in particle agglomeration. In order to understand the crystallite size of ZnO and ZnO-SiO2 nanocomposite were found to be 44.37 nm and 34.09 nm respectively. Practically, both synthesized ZnO and ZnO-SiO2 nanocomposite applied for the preparation of biodiesel applications. Biodiesel is an alternative to petroleum-based diesel that is biodegradable, non-toxic and being less polluting. Based on the literatures, they produced biodiesel from waste cooking oil using transesterification process with ZnO and ZnO-SiO2 nanocomposite as heterogeneous catalysts. The fame conversion was confirmed by FTIR and GCMS analysis. The prepared biodiesel was characterized by its physical and fuel properties like density, kinematic viscosity, flashpoint and calorific value.

Optimization of FAME composition for improved engine performance and emissions reduction

Abstract Continuous application of biodiesel as an alternative fuel for compression ignition (CI) engines has necessitated the need to unearth an optimal mix to enhance engine performance and mitigated emissions. This particular work employed a numerical approach to solve linear equations generated for biodiesel properties using fatty acid (FA) composition for the determination of an optimal fatty acid methyl ester (FAME) candidate. Transesterification of waste vegetable oil employed to experimentally produce the FAME candidate generated through numerical intervention. The gas chromatography-mass spectrometer analysis of the resulting FAME revealed that the type of used vegetable oil, the food the oil was used to fry and catalyst particle size influenced the FA composition of the FAME. Numerical evaluation of the objective function and the constraints yielded a FAME candidate with palmitic and oleic acids at 36.4% and 59.8%, respectively. The outcome of this research indicates that two FA compositions are enough to describe optimized FAME candidate for better engine performance and reduced emissions of an unmodified CI engine.

Screening of three Chlorella mutant strains with high lipid production induced by 3 types of lasers

There are many studies on the use of lasers as a special mutation-breeding method to select microorganisms and plant seeds. In this study, we screened 72 microalgal mutants from the Chlorella samples irradiated using three types of laser (He-Ne, Nd:YAG and SC). Finally, 2 mutants N2 and S3 from wild Chlorella pyrenoidosa, and 1 mutant, N3 from Chlorella pacifica having high potential for biodiesel applications with high yield and stability, were obtained after comprehensive comparison and systematic screening. The average total lipid productivities of the 3 mutants were 19.90 ± 2.46 mg L−1 day−1 for N2, 29.82 ± 4.45 mg L−1 day−1 for S3 and 20.56 ± 5.69 mg L−1 day−1 for N3, respectively. The 3 mutants were proved they could display higher lipid productivity, lipid content, growth rate and transcriptional expression trends of 7 genes relevant to fatty acid biosynthesis than the wild strain in 10 continuous generation subcultures.

Selection of the most beneficial raw materials for the synthesis of biodiesel from a standpoint of its yield and physicochemical properties

Biodiesel presents itself as one of the most promising alternative energy sources at the present time, both as a pure fuel and a mixed component of petroleum-based diesel fuels. According to research works carried out around the world, the addition of biodiesel to diesel oil is established to significantly improve the environmental friendliness of this oil product. Nevertheless, its effect on most regulated operational indicators remains ambiguous due to the characteristics of biodiesel fuel varying greatly depending on the feed-stock. The present paper is aimed at resolving the issue of selecting the most beneficial raw material for the synthesis of biodiesel from the perspective of the target product yield, physicochemical and low temperature characteristics. In this study, biodiesel was synthesised from five different edible vegetable oils (sunflower, mustard, linseed, corn and camelina) using ethanol and potassium hydroxide as transesterifying agent and catalyst, respectively. The main physicochemical (density, dynamic and kinematic viscosity, molecular weight) and low-temperature (cloud point and pour point) properties of vegetable oils, as well as biodiesel fuels derived therefrom, are determined. According to the obtained yield values of the target product, sunflower oil is shown to be the optimal raw material for the synthesis of biodiesel. From the position of their physical and chemical properties, sunflower and corn oil appear to equally preferential, while, with regard to low temperature properties, mustard oil turns out to be the optimal feedstock. Sunflower oil was additionally determined to be a leader in terms of economics. The paper presents recommendations for choosing the most preferable raw materials for the synthesis of biodiesel, which are useful in application of biodiesel as a mixed component for commercial diesel fuels.

Application of biodiesel for 12-cylinder, supercharged military combat vehicle

During wartime and disaster management military logistics such as combat vehicles, heavy-duty trucks must be capable of any transportation fuel available in forward area. In present work potential use of biodiesel derived from Karanja and Jatropha oil was investigated for a heavy-duty military vehicle. Performance and emissions of 12 cylinders, supercharged diesel engine was evaluated using JP-8, Karanja Oil Methyl Ester (KOME) and Jatropha Oil Methyl Ester (JOME) and compared with baseline standard diesel at variable speed range. Engine performance was slightly reduced with KOME and JOME. However from emission point of view, both the biodiesels contributed to reduction in CO and HC emissions as well as smoke opacity, with penalty in NO x emissions. Reduction in exhaust sound was seen for biodiesel fuels which is of upmost important during wartime. Thus, biodiesels can be used for military combat vehicles without any modifications in existing engine configurations.

Plant hormone induced enrichment of Chlorella sp. omega-3 fatty acids

BackgroundOmega-3 fatty acids have various health benefits in combating against neurological problems, cancers, cardiac problems and hypertriglyceridemia. The main dietary omega-3 fatty acids are obtained from marine fish. Due to the pollution of marine environment, recently microalgae are considered as the promising source for the omega-3 fatty acid production. However, the demand and high production cost associated with microalgal biomass make it necessary to implement novel strategies in improving the biomass and omega-3 fatty acids from microalgae.ResultsFour plant hormones zeatin, indole acetic acid (IAA), gibberellic acid (GBA) and abscisic acid (ABA) were investigated for their effect on the production of biomass and lipid in isolated Chlorella sp. The cells showed an increase of the biomass and lipid content after treatments with the plant hormones where the highest stimulatory effect was observed in ABA-treated cells. On the other hand, IAA showed the highest stimulatory effect on the omega-3 fatty acids content, eicosapentaenoic acid (EPA) (23.25%) and docosahexaenoic acid (DHA) (26.06%). On the other hand, cells treated with ABA had highest lipid content suitable for the biodiesel applications. The determination of ROS markers, antioxidant enzymes, and fatty acid biosynthesis genes after plant hormones treatment helped elucidate the mechanism underlying the improvement in biomass, lipid content and omega-3 fatty acids. All four plant hormones upregulated the fatty acid biosynthesis genes, whereas IAA particularly increased omega-3-fatty acids as a result of the upregulation of omega-3 fatty acid desaturase.ConclusionsThe contents of omega-3 fatty acids, the clinically important compounds, were considerably improved in IAA-treated cells. The highest lipid content obtained from ABA-treated biomass can be used for biodiesel application according to its biodiesel properties. The EPA and DHA enriched ethyl esters are an approved form of omega-3 fatty acids by US Food and Drug Administration (FDA) which can be utilized as the therapeutic treatment for the severe hypertriglyceridemia.

Extraction of Muriella decolor lipids using conventional and pressurized solvents and characterization of their fatty acid profile for biodiesel applications

Microalgae have been described as a sustainable feedstock for biodiesel production. In this work, Muriella decolor lipids were extracted using pressurized (compressed propane, scCO2 and scCO2 followed by scCO2+ethanol) and conventional solvents (hexane, ethanol and chloroform:methanol). Total fatty acid methyl esters (FAMEs) in the unextracted biomass and solvent extracts were quantified and their profiles were determined by gas chromatography. Hexane was more selective for saponifiable lipids, whereas ethanol and chloroform:methanol resulted in higher yields of crude extracts. Among compressed fluids, propane led to both higher extraction yield and higher selectivity for saponifiable lipids, leading to 67.5% of the total FAME yield of hexane extracts. Sequential extractions using scCO2 followed by three stages of scCO2+EtOH improved extraction yields, reaching values (16.37 wt.% for a total FAME yield of 5.87 wt.%) higher than those obtained by conventional solvents. However, the selectivity for saponifiable matter decreased from the first extraction step.

The implementation of artificial neural networks for the multivariable optimization of mesoporous NiO nanocrystalline: biodiesel application.

In the present research, artificial neural network (ANN) modelling was utilized to determine the relative importance of effective variables to achieve optimum specific surface areas of a synthesized catalyst. Initially, carbonaceous nanocrystalline mesoporous NiO core–shell solid sphere composites were produced by applying incomplete carbonized glucose (ICG) as the pore directing agent and polyethylene glycol (PEG; 4000) as the surfactant via a hydrothermal-assisted method. The Brunauer–Emmett–Teller (BET) model was applied to ascertain the textural characteristics of the as-prepared mesoporous NiO catalyst. The effects of several key parameters such as metal ratio, surfactant and template concentrations, and calcination temperature on the prediction of the surface areas of the as-synthesized catalyst were evaluated. In order to verify the optimum hydrothermal fabrication conditions, ANN was trained over five different algorithms (QP, BBP, IBP, LM, and GA). Among five different algorithms, LM-4-7-1 representing 4 nodes in the input layer, 7 nodes in the hidden layer, and 1 node in the output layer was verified as the optimum model due to its optimum numerical properties. According to the modelling study, the calcination temperature demonstrated the most effective parameter, while the ICG concentration indicated the least effect. By verifying the optimum hydrothermal fabrication conditions, the thermal decomposition of ammonium sulphate (TDAS) was applied to the functionalized surface areas and mesoporous walls by –SO3H functional groups. In addition, the catalytic performance and reusability of the produced mesoporous SO3H–NiO catalyst were evaluated via the transesterification of waste cooking palm oil, resulting in a methyl ester content of 97.4% and excellent stability for nine consecutive transesterification reactions without additional treatments.

Application with initiative to replace common insect fuel for fogging system with biodiesel

The project addressed the application of biodiesel as a fuel in replacing the petroleum-based liquid carrier in common fogging system. In controlling the population of larvae and adult mosquito using chemical pesticide spraying through fogging method, the dilution rate based on the efficient mixing of pesticide and biodiesel is yet to be investigated. A simulation field trial was conducted indoor in a visible container with the designed dimension of 50 cm × 50 cm × 50 cm with the method of fogging was adapted from the principle of thermal fogger. The biodiesel was produced through the transesterification reaction of palm oil with methanol using hydrotalcite as catalysts. To evaluate the larvicidal and adulticidal mortality, dilution of pesticide which is Sumithion L-40 into biodiesel as liquid carrier is varied. The 5 ml pesticide-carrier mixture with the dilution ratio of 1:9, 3:7 and 5:5 were used and dispersed into the ambient in the form of fog. After several tests, it can be deduced that the most effective dilution ratio for against larvae is 1:9 and adult mosquito is 5:5. The larvae mortality rate achieved 100% at the duration of 117 min due to effective settlement of the spraying droplet of formulation mixture on exposed water. The result also proven that, biodiesel as liquid carrier capable to overcome the solubility problem encountered by the conventional petroleum-based carrier. The adult mosquito needs shorter knockdown time with the higher dosage of pesticide. Sumithion L-40 consists of two active ingredients which are tetramethrin and fenitrothion that provide quick knockdown and residual effect especially to adult mosquito.

ZrO2 nanoparticles mediated flocculation and increased lipid extraction in chlorococcum sp. for biodiesel production: A cost effective approach

Herein, zirchonium di-oxide nanoparticles (ZrO2-Nps) were selected best for cell recovery and lipid extraction for microalgae Chlorococcum sp. Optimization of ZrO2-NPs concentrations by varying time intervals was done to achieve maximum cell recovery. The flocculation efficiency of 99.59% was achieved at the elevated pH (pH 10) providing 15 mg/L of ZrO2-NPs, simultaneously 2.07 folds of increase in lipid content was observed. The extracted lipids were converted into fatty acid methyl esters (FAME) and recorded with higher amount of saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA) making it preferable for biodiesel application. The ZrO2-NPs were characterized by various analytical techniques for its application in microalgae system.

Statistical Approach of Nutrient Optimization for Microalgae Cultivation

The Plackett-Burman Design (PBD) was applied to study fresh water microalgae cultivation using Chlorella sp. TISTR 8411 to select the influential nutrient factors for biomass and lipid production. The PBD for 13 trials from 11 nutrient factors with 3 levels was studied in the mixotrophic cultivation at 28 0C under 16:8 light and dark photoperiods over 7 days of cultivation time. Two influential factors were chosen as glucose and cobalt chloride hexahydrate to further design via Box-Behnken Design (BBD) in order to optimize the cultivation of this microalgae for biodiesel production. The 17 trials of 3 factors and 3 levels of BBD experimental design technique were applied with varying factors of glucose (20-40 g/L), cobalt chloride hexahydrate (0.01-0.04 mg/L) and light intensity (4,500-7,500 Lux) under 16:8 light and dark photoperiods over 7 days of cultivation time at 28 0C. Result showed that Chlorella sp. TISTR 8411 cultivation yield 0.52 g/L biomass and 0.31 g/L lipid production resulting in approximately 60% of lipid production when cultivated in 20.05 g/L glucose, 0.04 mg/L CoCl26H2O under light intensity of 4,614 Lux with the supplementation of 4.38 g/L NaHCO3 coupled with 1 g/L of both NaNO3 and KH2PO4. Under statically mixotrophic cultivation, result indicated that Chlorella sp. TISTR 8411 had potential to produce high lipid content for biodiesel application and biomass production for nutraceutical application. Further experiment with the longer cultivation period up to 2 weeks would implement not only for monitoring the growth kinetics but also evaluating the suitable type of fatty acid production.

Mathematical modeling of ethanol production from glycerol by Enterobacter aerogenes concerning the influence of impurities, substrate, and product concentration

The application of biodiesel derived crude glycerol for ethanol production using Enterobacter aerogenes TISTR 1468 involved multiple interactions among substrate (glycerol), impurities (methanol) and product (ethanol and acetic acid). A mathematical model based on Monod and Luedeking-Piret models were established to simulate the cell performance in the presence of inhibitors. The Monod model was modified by adding the inhibition factors in terms of critical concentration (C*Ac< C*EtOH< C*MeOH< C*Gly) and its inhibition degree (ni) (nGly>nMeOH>nAc>nEtOH with the values of 119.06, 13.33, 1 and 0.0383, respectively). The Luedeking-Piret model confirmed that ethanol and acetic acid were predominantly growth-associated products. Glycerol up to 24.31 g/L and 31.32 g/L were optimum for cell growth and ethanol productivity, respectively. The cell performance was affected by methanol even at its lowest concentration tested (7.92 g/L). The applicability of the new two-phase growth model during the growth phase and stationary phase in the crude glycerol medium was validated and proved accurate (r2> 0.98).

Research Progress on Preparation of Biodiesel by Transesterification

The preparation of biodiesel by transesterification was systematically described. According to the different types of catalysts, four transesterification methods, such as acid catalysis, alkali catalysis, enzymatic catalysis and supercritical method, were introduced in detail. The advantages and disadvantages of these four methods are analyzed, aiming at providing reference for the research and development and application of biodiesel in transesterification.