Unsaturated Fatty Acid Methyl Esters Research Articles

A comparative study on biodiesel production from edible and non-edible biomasses

Biodiesel is a renewable and environmentally friendly alternative to traditional diesel fuel. It can be produced from various sources, primarily through homogeneously alkali-catalyzed transesterification. However, with the increasing demand for edible oils and the ongoing concerns about using edible resources for fuel, non-edible oils have become more attractive for biodiesel production. Non-edible oils, such as those derived from waste oils, offer a more sustainable and environmentally friendly source for biodiesel production. The current study compares biodiesel samples’ properties derived from an uncooked sunflower oil sample provided by a local bio-industry and four waste cooking oil samples collected from a local restaurant and fast food shop. The findings indicated that most biodiesel properties from edible and non-edible biomass feedstocks were found to be similar and met the specifications outlined in the EN 14,214 standard. Nevertheless, the oxidation stability and the viscosity were found to be outside the specified limits in most of the samples. Additionally, GC–MS analysis exhibited a similar composition of fatty acid methyl esters (FAMEs), with a high proportion of unsaturated FAMEs in all biodiesel samples.

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.
 
 Keywords: Green microalgae, Chlorella spp., Total lipid content, Lipid composition, Biodiesel

Highly selective production of high purity methyl oleate biodiesel by silver-based deep eutectic solvent extraction

High-purity methyl oleate is one of the important oleo-chemical products with a wide range of applications (e.g., biodiesel). In this study, an efficient extraction method based on a silver-based deep eutectic solvent (Ag-DES) has been developed for separating high purity (>98 %) methyl oleate from unsaturated fatty acid methyl esters (e.g., camellia seed oil methyl esters). The rapid extraction method involving silver ions can selectively separate the unsaturated fatty acid methyl esters (FAMEs) by forming C = C double bond complexes with the unsaturated FAMEs. Ag-DES exhibited highly selectivity towards monounsaturated FAMEs (C18:1) and polyunsaturated FAMEs (C18:2, C18:3). The extraction conditions of Ag-DES were optimized and its recyclability was investigated. Under the optimal conditions (room temperature extraction for 10 min), the yield of high-purity methyl oleate (98.5 %) was greater than 60 %, while the selectivity of methyl oleate reached 48.07. The Ag-DES could be successfully recycled for 5 times without loss of extraction selectivity. Thus, this sustainable extraction can provide a simple method for producing a biodiesel with excellent oxidative stability.

The vaporization enthalpies and vapor pressures of Vescepa® and related unsaturated marine FAME by correlation gas chromatography

This article combines data from two previous reports together with new data dealing with the vaporization enthalpies and vapor pressures of a series of saturated and unsaturated fatty acid methyl ester(s) (FAME) by correlation gas chromatography. The work updates earlier results using newly proposed vaporization enthalpies for the saturated FAME used as standards in previous work. This update also provides some insight into the requirements necessary for appropriate column and standard selection for experiments using correlation gas chromatography. Vaporization enthalpies and vapor pressures for saturated FAME methyl heneicosanoate, methyl docosanoate, and methyl tetracosanoate are re-evaluated and together with proposed literature values for methyl tetradecanoate to methyl eicosanoate, are used to evaluate similar properties for a series of unsaturated fatty acid esters. Updated results on the vaporization enthalpies and vapor pressures of a number of unsaturated fatty acid methyl esters (FAME) found in marine oil are reported including several relatively reactive omega-3-polyunsaturated esters. Omega-3-FAME include methyl (9,12,15)Z-octadecatrienoate, methyl (5,8,11,14,17)Z-eicosapentaenoate, and methyl (4,7,10,13,16,19)Z-docosahexenoate among other unsaturated methyl esters. Also included in the study of the omega-3-unsaturated esters is the drug Vescepa®, ethyl (5,8,11,14,17)Z-eicosapentaenoate, a drug used to lower triglyceride levels.

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

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

Optimization of microwave-assisted biodiesel production from watermelon seeds oil using thermally modified kwale anthill mud as base catalyst

A heterogeneous catalyst was developed from raw Kwale red Anthill mud by thermal treatment in a muffle furnace at 900 °C for 4 h. The resulting heterogeneous catalyst was highly porous with a surface area of 42.16m2/g, possessing excellent stability as well as high catalytic activity. Central Composite Design and Machine Learning approach (Python code) were applied to model and optimize biodiesel yield from extracted watermelon oilseed. Highest biodiesel yield of 93.41 wt% was obtained under the experimental conditions of 4min duration, 350 W microwave power, 4 wt% of catalyst, and MeOH/oil ratio of 8:1 based on Central Composite Design rotatable. The optimum value of the biodiesel yield from Machine Learning was 91.7 wt%, showing a marginal performance over the Central Composite Design rotatable value (91.6 wt%) at the optimized conditions of 3 min, 280 W, 3 wt% catalyst loading and MeOH/oil molar ratio of 6:1. The correlation of the coefficient (R2) of the model was 0.9827 for Central Composite Design rotatable while the R2 of the Machine Learning model was 1.0. Thus, python coding in terms of prediction and accuracy of biodiesel yield was superior to Central Composite Design rotatable, even though both models provide a reliable response within the region of data analyzed. The Gas Chromatography-Mass Spectroscopy of the biodiesel produced revealed the presence of both saturated and unsaturated fatty acid methyl esters. Biodiesel properties from watermelon seed oil transesterification fall within the recommended standard for biodiesel fuel. This study concluded that an effective green biowaste catalyst generated from earthen waste could enhance biodiesel production from watermelon seed oil, hence, ensuring sustainability and economic feasibility for biodiesel industries.

Biodegradation of quinoline by Nitrosomonas mobilis Ms1 through nitrification: A mechanistic study

Effluents from pharmaceutical and coal gasification industries contain recalcitrant aromatic pollutants such as quinoline. Ammonia oxidizing bacteria (AOB) has been known to simultaneously oxidize ammonia and aromatic compounds. This study investigated the impact of quinoline, a nitrogen-containing heterocyclic aromatic compound, on nitrification by pure culture of AOB- Nitrosomonas mobilis Ms1. Quinoline has been found to inhibit nitrification to suspension culture by IC 50 value 40.01 μM. However, biofilm culture could withstand its inhibitory effect upto 50 μM. Morphological analysis of biofilm culture showed destruction in extracellularpolymeric substances (EPS) in the presence of quinoline at concentration of 1.5 mM and above. X-ray photoelectron spectroscopy (XPS) analysis of the biofilm surface showed loss of NH4+ peak in quinoline treated biofilm which indicated lower protein in EPS. Biodegradation analysis showed pyridine derivatives – 2,3-Pyridinedicarbonitrile, 2,4-Dicyanopyridine, and Pyridine, 2-[(3-methoxyphenyl) methyl] and hydroxylated aromatic such as 3-Hydroxy-4-methylbenzaldehyde and phenol, 4-[2-(methylamino) ethyl] as metabolic intermediates of quinoline degradation. These metabolic intermediates have been found to inhibit nitrification by blocking enzyme active site. Quinoline caused change in fatty acid methyl ester (FAME) profile which resulted in higher fraction of unsaturated FAME. This is one of the pioneer studies on quinoline biodegradation by a pure culture of AOB species, which could in turn aid to improve the efficacy of biological treatment of nitrogen-containing (heterocyclic compounds such as quinoline) wastewater.

Stability of a Silica‐Supported Second Generation Hoveyda‐Grubbs Catalyst Under Atmospheric Conditions: Experimental and Computational Studies

AbstractSecond generation Hoveyda‐Grubbs (HG2) is a reliable and extremely useful catalyst for the synthesis of olefins. Recent studies show that supported HG2 catalyst is particularly well suited for the self‐metathesis reaction of unsaturated fatty acid methyl esters, such as methyl oleate (MO), among other applications. Within the various supports that have been studied, silica gel appears as one of the most promising for large scale application of heterogeneous HG2. In this work we found that although the catalyst supported on silica gel retains its activity when stored under strictly controlled conditions (vacuum, 253 K), the activity deeply decreases when the supported complex is stored under atmospheric conditions at 298 K, compromising the stability and applicability of the heterogeneous catalyst. We carried out a detailed experimental and spectroscopic study of the deactivation process of the supported catalyst, which, aided by electronic structure calculations, allowed us to throw some light onto the catalyst decomposition process.

Numerical simulation of a diesel engine performance powered by soybean biodiesel and diesel fuels

BackgroundThe present study presents a 3-D numerical simulation of a direct injection diesel engine powered by base diesel oil and soybean biodiesel fuel at different load conditions. The modeling was performed using commercial computational fluid dynamics (CFD) software linked to a chemical solver. A chemical kinetic reaction mechanism was developed to simulate the combustion and fuel spray processes. Base diesel oil results were verified using a single-cylinder, 4-stroke diesel engine.ResultsThe study showed that the usage of the soybean biodiesel fuel caused a reduction in carbon monoxide (CO) and hydrocarbon (HC) emissions by about 42.38% and 41.35%, compared with base diesel and an increase in nitrogen oxides (NOx) and carbon dioxide (CO2) emissions of about 21.8% and 11.2%, respectively. Exhaust gas temperature (EGT) is reduced by an average value of 9.4%, the brake-specific fuel consumption (BSFC) is increased by an average value of 11.8% and the brake thermal efficiency (BTE) is dropped by an average value of 11.3% for soybean biodiesel fuel.ConclusionsThe CFD model showed the effect of the unsaturated fatty acid methyl esters present in soybean biodiesel on the spatial distributed values of NOx, oxygen and temperature during the combustion in engine cylinder. It was observed that the combustion of soybean biodiesel began about 3.89 CAD earlier than base diesel, and the in-cylinder peak pressure was dropped by 8.25%. Soybean biodiesel fuel was optimized by performing four starts of injection (SOI) at timings of − 18, − 16, − 15 and − 13,5 bTDC, and it was found that the combustion characteristics of soybean biodiesel are optimum at SOI = − 15 bTDC. These results indicate that the biodiesel fuel can be used as an alternative and environmentally friendly fuel in the engine without any modifications.

Two approaches for bio-lubricant production from soybean oil with organosilicon

With the rapid increasing of environmental pollution concerns and declining petroleum assets, bio-based lubricants industry has aroused increasingly more attention and study. The present paper proposed two methods (a two-step process and a direct hydrosiylation process) for the production of biolubricant from soybean oil with organosilicon. At first, soybean oil was subjected to transesterification with potassium hydroxide under certain conditions. Then, the transesterified soybean oil was undergone urea inclusion for obtaining unsaturated fatty acid methyl esters (UFAMEs). After urea inclusion, the content of UFAMEs was increased to 88.1%. Next, the chemical modification of UFAMEs by the two-step process (epoxidation and ring-opening reaction) and the direct hydrosiylation process (with triethylsilane in present of catalyst) were systematically studied, respectively. With the optimal conditions, the conversions of UFAMEs in the two-step process and direct hydrosiylation process were 86.1% and 82.1%, respectively. In addition, the structure characteristics of material and products were determined by Fourier-transformed infrared (FTIR) spectroscope and 29Si-Nuclear magnetic resonance (29Si-NMR) spectrascopy. The lubrication performances of the two products were proved to be much better than soybean oil according to industry standards. Therefore, both of the two processes appeared to be feasible for bio-lubricant production.

Synergistic effect in co-processing a residue from a transesterification process with vacuum gas oil in fluid catalytic cracking

• Co-processing of bio-oil in existing fluid catalytic cracking unit produces biofuel. • Bio-oil oxygen content determines its blends level with vacuum gas oil or VGO. • Distillation residue from biodiesel production using waste fats and oil is used. • Synergistic effect of bio-oil and VGO shows yield of gasoline higher than predicted. • Cracking of 10 wt% bio-oil has the closest coke characteristics compared to VGO. The catalytic co-processing of bottom fuel oil (BFO) with refinery vacuum gas oil (VGO) using a commercial fluid catalytic cracking (FCC) zeolite equilibrium catalyst was carried out to ascertain its potential as a source for biofuels. The BFO used was the distillation residue from biodiesel transesterification process using waste fats and oil; being a mixture of saturated and unsaturated fatty acid methyl esters. The catalytic cracking experiments were performed in a laboratory fixed bed micro activity test (MAT) reactor at 516 °C and atmospheric pressure. As well as the VGO and BFO, three different blends were used with BFO to VGO mass ratios of 10:90, 20:80 and 50:50, and catalyst-to-oil (C/O) ratios of 3.0 – 5.7. The synergistic effect of BFO in VGO blends includes the yield of gasoline, and LPG being higher than predicted for the blends of 10 wt% BFO in VGO. Also, the formation of more CO 2 with the increase in BFO blend level suggests CO 2 production through decarboxylation reactions as a possible route. The compositions of the produced gasoline for pure VGO and 10 wt% BFO are similar as well. The cracking of 10 wt% BFO gives a higher fraction of aromatics, alkenes and naphthenes than other blends. However, some deterioration was observed when higher substitution levels of BFO were used, resulting in a decrease in the gasoline yield and higher yields of LCO, HCO and coke as predicted. Overall, co-processing BFO with VGO may be economically attractive because the BFO is obtained from waste oils and fats which are one of the under-exploited sources of biodiesel feedstocks and add value to waste management.

Novel thermal conductivity-mixing ratio-temperature mathematic model for forecasting the thermal conductivity of biodiesel-diesel-ethanol blended fuel

ABSTRACT To explore the thermal conductivity of diesel-biodiesel-ethanol blended fuel under different temperatures and mixing ratios, three ternary blended fuels, namely, Jatropha/soybean/catering waste oil biodiesel-diesel-ethanol, were prepared. The three biodiesel components were analyzed using gas chromatography-mass spectrometry. A Hot Disk 2500S thermal constant analyzer was used to measure the thermal conductivity of the blended fuels in the temperature range of 20–60°C. Thermal conductivities of the three blended fuels increased with increase in temperature, and the three blended fuels had different thermal conductivities at the same temperature and mixing ratio. This may be attributed to the different contents of unsaturated fatty acid methyl esters in the blended fuels. The optimal mixing ratio was determined to be 80% diesel, 15% biodiesel, and 5% ethanol. Further, a thermal conductivity (λ) forecasting model related to temperature (t) and mixing ratio (w) was established based on experimental results, and its accuracy was evaluated using correlation coefficients and the average absolute percentage error. The value of the correlation coefficient reached 0.9700 for all three blended fuels, and the value of the average absolute percentage error was 0.2738, 0.2823, and 0.8596%, respectively. Thus, the variation of fuel thermal conductivity with temperature and mixing ratio could be accurately predicted. The findings of this study provide insights for designing thermophysical parameters of biodiesel.

The effect of biodiesel production method on its combustion behavior in an agricultural tractor engine.

In this study, biodiesel fuel was produced from waste cooking oil (WCO) using a heterogeneous catalyst under microwave (MB) and conventional (CB) heating, and fueled in an agricultural tractor engine to evaluate the engine performance as well as emissions. The biodiesels presented different fatty acid methyl ester (FAME) profiles where MB had lower unsaturated FAME chains. Beyond the transesterification reaction time, the energy consumed for MB biodiesel production diminished by around eight times compared to that required for CB production. The engine results confirmed the positive influence of blending net diesel fuel with biodiesel for enhancing the engine performance and reducing the emissions. More than 20% increment in the engine power and torque was detected at all engine loads (the engine speed was adjusted at 1500rpm). The hydrocarbon (HC), carbon monoxide (CO), and smoke opacity (SO) indicated significant reductions compared to when net diesel fuel was used. According to statistical analysis, CB25 and MB25 fuels presented a suitable combination as fuel where MB25 provided better engine performance, lower HC and SO emissions, with CO emissions reaching the minimum amount by CB fuels.

Thermodynamically predicting liquid/solid phase change of long-chain fatty acid methyl esters (FAMEs) and its application in evaluating the low-temperature performance of biodiesel

BackgroundLong-chain FAMEs, also called biodiesel, are viewed as the alternative to petroleum diesel for renewability and sustainability. Because the fatty acid profiles significantly varied for the sources, the compositions significantly affected the biodiesel properties, such as cloud points. The cloud point of biodiesel indicates the phenomenon of solid-liquid phase change. Previous models for cloud point predictions were limited to known components in the mixtures. MethodsThe cloud points of the binary, ternary and multicomponent mixtures of fatty acid methyl esters were measured in this study. A cloud point prediction model was established based on phase equilibrium with the modified Universal functional activity coefficient (UNIFAC) model and excess fusion enthalpy for predicting the nonideal behaviors of the components resulting from the molecular shape and molecule interactions. Significant findingsThe developed thermodynamic model accurately predicts the cloud point according to compositions. The model extends the application scope to the low-temperature range. There had eutectic points in the phase diagrams when the mixtures consisted of either saturated FAMEs or unsaturated FAMEs. This study proved that saturated FAMEs regulate the cloud points, but unsaturated FAMEs affect them through group interactions. Moreover, the proposed model can predict unknown FAMEs mixture as it is built on the group contributions.

Silver ion functionalized covalent organic polymer for selective online solid phase microextraction of unsaturated fatty acid methyl esters

In this work, silver ion functionalized covalent organic polymer (COPTAPB-BPDA@SA@Ag+) was fabricated via the introduction of silver ion to COP, and utilized as selective sorbent for online SPME of unsaturated fatty acid methyl esters (UFAMEs). The synthesis of COPTAPB-BPDA@SA@Ag+ was confirmed by using the SEM, EDS, FT-IR, XRD and XPS characterization techniques. Due to the charge-transfer interaction between silver ion and C = C double bonds, COPTAPB-BPDA@SA@Ag+ displayed satisfactory extraction ability towards UFAMEs. Several SPME factors, such as ACN content in the sampling solution and eluent, sampling and elution flow rate, were investigated with respect to the extraction efficiency of UFAMEs. Under the optimized conditions, an online Ag+-SPME-Ag+-HPLC method for analysis of target trans-UFAMEs was proposed. A good linearity was established in the range of 0.04 ∼ 2 mg/kg for two target trans-UFAMEs in milk tea samples. The limits of detection (LODs) and limits of quantitation (LOQs) were not more than 8.8 μg/kg and 19 μg/kg respectively, while the intra-day RSDs (n = 3) and the inter-day RSDs (n = 3) were less than 2.1% and 2.9% respectively. The recoveries for the proposed method was ranged from 82.3% to 93.5% with RSDs (n = 4) less than 5.9%. The above results demonstrated the selective extraction of COPTAPB-BPDA@SA@Ag+ towards UFAMEs from complex real samples, as well as the satisfactory detection sensitivity for trans-fatty acids of the proposed method. This study provided a facile approach for the preparation of metal ion functionalized COP sorbent and showed its wide potential for sample preparation.

Effect of Thermal Treatment and Nickel-Salt Modification on the Catalytic Performance of the Illite-Kaolinite Clay from Bukittinggi of West Sumatra in Palm Oil Transesterification

The effect of thermal and chemical modification on the catalytic performance of illite-kaolinite clay (obtained from Bukittinggi, West Sumatra) in the transesterification of palm oil was investigated. Characterization with XRD, XRF and FTIR indicated a slight change in the composition of the crystal phase and the Si/Al molar ratio after such clay was calcined at 450 °C. XRF measurements also confirm that after treatment with two nickel salts, the natural clay absorbs more nickel sulfate than nitrate, while temperature played an important role in increasing the performance of the clay in loading nickel about 2 times bigger at a higher temperature. All clay-based materials prepared in this study were tested for their catalytic activity and selectivity in the transesterification of palm oil to produce Fatty Acid Methyl Ester (FAME) using the previously reported procedure. Chemical modification of clay samples with nickel sulfate and nickel nitrate was found to increase the catalytic performance of the clay in producing FAME from 38 to about 60 % while thermally treated at 450 °C yielded slightly higher to about 67 %. In terms of selectivity, all clay-based catalysts in this study gave almost the same amount of saturated and unsaturated FAME

Investigation of flame structure and stabilisation characteristics of palm methyl esters diffusion flames

Experiment and numerical analysis were conducted to investigate the flame structure and stabilisation characteristics of palm methyl esters (PME) diffusion flame. In the experiment, nitrogen-diluted biodiesel mixtures with fuel mole fraction range from 0.02 to 0.03 were supplied to the nozzle through a pre-heated pipeline at a temperature of 550 K. The results showed that the stabilisation of the PME lifted flames was mainly controlled by the jet momentum, especially in the jet developed region, whereas the role of the buoyancy in the stabilisation of the lifted flame was not significant. In the simulation, biodiesel lifted flames were modelled using open-source tool, laminarSMOKE in OpenFOAM. Numerical analysis revealed that the stabilisation mechanism of the lifted flames at jet momentum dominated regime could be based on the factors that affect the edge flame propagation speed, such as mixture strength and fuel Lewis number. Additional numerical simulations were also carried out to investigate the role of each fatty acid methyl ester (FAME) component on the liftoff behaviour, and it was found that the unsaturated FAME, methyl oleate, has a lower liftoff height compared to the saturated FAME, methyl palmitate due to the higher reactivity of the methyl oleate.

Dual nutrient heterogeneity modes in a continuous flow photobioreactor for optimum nitrogen assimilation to produce microalgal biodiesel

The impact of different nitrogen sources on the microalga, Chlorella vulgaris, was studied in a newly developed microalgal-bacterial photobioreactor via a dual nutrient heterogeneity mode. The mechanisms of nitrogen transformation and valorisation were unveiled, and subsequently, optimized via dual nutrient heterogeneity feeding modes comprising of various NH4+-N and NO3−-N concentrations. The nitrogen-assimilation mechanism from the microalgal-bacterial consortium was found to reduce microalgal growth inhibition, stemming at high NH4+-N concentrations. Accordingly, the total nitrogen removal efficiency was enhanced from 40.91% to 96.38% accompanied with maximum microalgal biomass production of up to 792 mg/L at a balanced or higher NH4+-N loading from mixed nitrogen environment. The harvested microalgal biomass contained high lipid accumulation of approximately 30% when fed with optimum NH4+-N and NO3−-N loadings at 60 and 58 mg/d, respectively. At this mixed nitrogen species loadings, high unsaturated fatty acid methyl esters (FAME) were attained. Indeed, the major FAME species (97%–100%) fell within the C16-18 range, signifying biodiesel characteristics conformity to the requirements for quality biodiesel application. Therefore, the dual heterogeneity modes of balanced NH4+-N and NO3−-N loadings into photobioreactor could offer effective microalgal nitrogen assimilation for sustainable wastewater treatment and microalgae-based biodiesel production simultaneously.

A 5-(2-Pyridyl)tetrazolate Complex of Molybdenum(VI), Its Structure, and Transformation to a Molybdenum Oxide-Based Hybrid Heterogeneous Catalyst for the Epoxidation of Olefins

There is a considerable practical interest in discovering new ways to obtain organomolybdenum heterogeneous catalysts for olefin epoxidation that are easier to recover and reuse and display enhanced productivity. In this study, the complex salt (H2pytz)[MoO2Cl2(pytz)] (1) (Hpytz = 5-(2-pyridyl)tetrazole) has been prepared, structurally characterized, and employed as a precursor for the hydrolysis-based synthesis of a microcrystalline molybdenum oxide/organic hybrid material formulated as [MoO3(Hpytz)] (2). In addition to single-crystal X-ray diffraction (for 1), compounds 1 and 2 were characterized by FT-IR and Raman spectroscopies, solid-state 13C{1H} cross-polarization (CP) magic-angle spinning (MAS) NMR, and scanning electron microscopy (SEM). Compounds 1 and 2 were evaluated as olefin epoxidation catalysts using the model reaction of cis-cyclooctene (Cy8) with tert-butyl hydroperoxide (TBHP), at 70 °C, which gave 100% epoxide selectivity up to 100% conversion. While 1 behaved as a homogeneous catalyst, hybrid 2 behaved as a heterogeneous catalyst and could be recovered for recycling without showing structural degradation or loss of catalytic performance over consecutive reaction cycles. The substrate scope was broadened to monoterpene DL-limonene (Lim) and biobased unsaturated fatty acid methyl esters, methyl oleate (MeOle), and methyl linoleate (MeLin), which gave predominantly epoxide products.

Intensification of catalytic transfer hydrogenation of fatty acid methyl esters by using ultrasound

Ultrasound was applied to intensity the catalytic transfer hydrogenation (CTH) of highly unsaturated fatty acid methyl esters (FAMEs) to realize the effective hydrogenation of FAMEs under mild conditions. Under the optimum reaction conditions of ultrasound-assisted CTH using La-doped nickel-boride amorphous alloy (Ni–La–B) as catalyst, sodium borohydride as hydrogen donor and water as solvent, a high conversion ratio of hydrogenation for polyunsaturated FAMEs could be easily realized at 35 °C at 120 min (ca. 78.66%). It was found that ultrasound presented a significant intensification effect on the CTH of FAMEs; different from the conventional and ultrasound approaches, by using ultrasound-assisted approach of CTH, deep hydrogenation could be avoided to a certain extent even under the high conversion ratio of hydrogenation, and the hydrogenated product with good performance was easily gained. The self-purification function of ultrasound on the catalyst played the most important positive effect on the intensification of CTH of FAMEs. Overall, the ultrasound-assisted approach played an effective process intensification on the CTH of FAMEs to produce high-quality products under mild conditions.