Esterification Of Free Fatty Acids Research Articles

Optimization of Methyl Oleate Synthesis with Sulfonated Pyrrolidonium Ionic Liquids as Catalysts Using the Response Surface Methodology

In order to improve the efficiency of biodiesel production from esterification of free fatty acids, an alternative to sulfuric acid has been explored in this study. These catalysts including three pyrrolidonium ionic liquids (ILs), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4), 2-pyrrolidonium hydrogen sulfate ([Hnhp]HSO4), and 1-(3-sulfonic acid) propyl-2-pyrrolidonium hydrogen sulfate ([C3SO3Hnhp]HSO4), were applied as catalysts to produce biodiesel through the esterification reaction of oleic acid with methanol. The catalytic performances of the synthesized ILs for the esterification of oleic acid were evaluated, and [C3SO3Hnhp]HSO4 exhibited the best catalytic activity among all tested acidic ILs. Moreover, the esterification of oleic acid with methanol by the [C3SO3Hnhp]HSO4-catalyzed was systematically explored, and the reaction conditions were further optimized through a single-factor experiment, the Plackett-Burman design, and a response surface methodology. It was found that optimum response for oleic acid conversion was 97.4% under reaction condition of using catalyst dosage of 12.5%, methanol/oleic acid molar ratio of 9:1, reaction time at 4 h and reaction temperature at 70 °C. In addition, the catalytic activity of [C3SO3Hnhp]HSO4 still remained high level after 5 cycles. In a conclusion, the IL [C3SO3Hnhp]HSO4 has great potential as a catalyst for producing fatty acid methyl esters via the esterification reaction.

Utilization of Keplerate-type polyoxomolybdates {Mo132} supported on hierarchical porous SOM-ZIF-8 as reusable catalyst boosts biodiesel production from acidic soybean oils by simultaneous transesterification-esterifications

Improving the reactant mass transfer on the catalyst surface is a feasible approach to fabricate a robust solid catalyst for efficiently promoting the biomass macromolecules-involving reactions, specifically for biodiesel production by using non-edible acidic oils as feedstocks. In this premise, to reduce the mass transfer resistance, the hierarchical porous SOM-ZIF-8 was firstly synthesized using polystyrene spheres (PS) as templates and then employed as catalyst supports for loading of Keplerate-type polyoxomolybdates {Mo132} to prepare a novel {Mo132}@SOM-ZIF-8 solid acid catalyst. The catalyst characterization results revealed that the active species of {Mo132} clusters were well-dispersed on the SOM-ZIF-8 support and the primary framework of the SOM-ZIF-8 support remained nearly unaltered after the preparation processes. This prepared catalyst featured three-dimensional ordered hierarchical porous structure and dual Bronsted-Lewis acid sites, with a large surface area of 736.26 m2/g and high acidity of 903 μmol/g, presenting high activities for concurrent triglyceride transesterification and free fatty acids (FFAs) esterification. With the acidic soybean oils as feedstocks, 93.9 % of oil conversion and full FFA conversion to biodiesel were achieved over this solid catalyst at 130 °C for 8 h with a catalyst loading of 2 wt%, thus imparting the great potential for a one-pot efficient biodiesel manufacture from the acidic oils to comply with the demand of green and clean production. The synergy between the hierarchical porous structure and the strong acidity emerged, thus boosting the catalytic performance of this solid catalyst for the heterogeneous biodiesel production. The good FFA and moisture-resistance capacity was shown for this catalyst even in the case of moisture content of 3 % and FFA content of 25 %. Further, this catalyst showed excellent reusability without significantly losing its catalytic performance even after five runs, providing a deeper insight into constructing efficient solid catalysts with hierarchical porous structure that are utilized for cost-effective production of biodiesel from the non-edible acidic oils.

Extending the computational and experimental analysis of lipase active site selectivity.

Molecular docking is an important computational analysis widely used to predict the interaction of enzymes with several starting materials for developing new valuable products from several starting materials, including oils and fats. In the present study, molecular docking was used as an efficient in silico screening tool to select biocatalysts with the highest catalytic performance in butyl esters production in a solvent-free system, an eco-friendly approach, via direct esterification of free fatty acids from Licuri oil with butanol. For such purpose, three commercial lipase preparations were used to perform molecular docking studies such as Burkholderia cepacia (BCL), Porcine pancreatic (PPL), and Candida rugosa (CRL). Concurrently, the results obtained in BCL and CRL are the most efficient in the esterification process due to their higher preference for catalyzing the esterification of lauric acid, the main fatty acid found in the licuri oil composition. Meanwhile, PPL was the least efficient because it preferentially interacts with minor fatty acids. Molecular docking with the experimental results indicated the better performance in the synthesis of esters was BCL. In conclusion, experimental results analysis shows higher enzymatic productivity in esterification reactions of 1294.83μmol/h.mg, while the CRL and PPL demonstrated the lowest performance (189.87μmol / h.mg and 23.96μmol / h.mg, respectively). Thus, molecular docking and experimental results indicate that BCL is a more efficient lipase to produce fatty acids and esters from licuri oil with a high content of lauric acid. In addition, this study also demonstrates the application of molecular docking as an important tool for lipase screening to achieve more sustainable production of butyl esters with a view synthesis of biolubricants.

A ketogenic diet lowers myocardial fatty acid oxidation but does not affect oxygen consumption: a study in overweight humans.

A ketogenic diet (KD) characterized by very low carbohydrate intake and high fat consumption may simultaneously induce weight loss and be cardioprotective. The "thrifty substrate hypothesis" posits that ketone bodies are more energy efficient compared with other cardiac oxidative substrates such as fatty acids. This work aimed to study whether a KD with presumed increased myocardial ketone body utilization reduces cardiac fatty acid uptake and oxidation, resulting in decreased myocardial oxygen consumption (MVO2 ). This randomized controlled crossover trial examined 11 individuals with overweight or obesity on two occasions: (1) after a KD and (2) after a standard diet. Myocardial free fatty acid (FFA) oxidation, uptake, and esterification rate were measured using dynamic [11 C]palmitate positron emission tomography (PET)/computed tomography, whereas MVO2 and myocardial external efficiency (MEE) were measured using dynamic [11 C]acetate PET. The KD increased plasma β-hydroxybutyrate, reduced myocardial FFA oxidation (p < 0.01) and uptake (p = 0.03), and increased FFA esterification (p = 0.03). No changes were observed in MVO2 (p = 0.2) or MEE (p = 0.87). A KD significantly reduced myocardial FFA uptake and oxidation, presumably by increasing ketone body oxidation. However, this change in cardiac substrate utilization did not improve MVO2 , speaking against the thrifty substrate hypothesis.

Hierarchical porous SAPO-34 decorated with Mo and W oxides for concurrent transesterification-esterifications for efficient biodiesel production from acidic soybean oil

Hierarchical porous materials have gained much attention as promising heterogeneous catalyst supports due to their high efficiency of mass transfer and high exposure of active centers. In this research, the hierarchical porous SAPO-34 support with microporous, mesoporous, and macroporous hierarchical structure was initially prepared by in-situ alkali etching. Then, Mo and W oxides were incorporated into this hierarchical porous support by using the impregnation method to prepare Mo15W15/HSAPO-34/70 catalyst. This developed catalyst was applied to concurrently catalyze the oil transesterification and free fatty acid (FFA) esterification to biodiesel as the low-value oils severed as feedstocks. The textural and physicochemical properties of the nanocatalysts were evaluated by XRD, XPS, SEM, EDS, TEM, UV–vis, NH3-TPD, Py-FTIR, and nitrogen porosimetry measurement. This catalyst had hierarchical porous structure to ameliorate the large oil molecular transfer, and featured dual Brønsted-Lewis acid sites to synergistically boost the catalytic efficiency for the biodiesel production. Over this catalyst, the oil conversion of 90.1 % and full FFA conversion were achieved under optimized operation conditions, therefore imparting to one-pot conversion to biodiesel with low-value oils as feedstocks. In addition, this catalyst not only exhibited superior tolerance to moisture and FFAs, but also retained high activities after five reuse cycles, thus revealing its tremendous potential of being used in durable and efficient biodiesel production. The present work opens a new avenue for synthesizing a robust solid acid catalyst to achieve a one-pot biodiesel production from low-value oils.

New route for preparing palmitic acid imidazole from free fatty acid using imidazole

In this study, imidazole was used for the first time in esterification of free fatty acid (FFA) from acidic oil and for palmitic acid imidazole production. The FFA content in jatropha oil mixed with crude palm oil (CPO) was significantly reduced from 10.57% to 1.73% under the following optimum conditions (25% imidazole dosage, 30 mins of reaction time, reaction temperature at 60 °C and methanol to oil molar ratio of 20:1). This research opens up new possibilities for utilizing imidazole as a catalyst in various esterification processes, offering a promising and eco-friendly pathway for industrial applications.

Studi Kinerja Mesin Diesel Berbahan Bakar Campuran Biodiesel Kacang Tanah Dan Solar

Biodiesel is an oil produced from vegetable oils or animal fats. Peanut is one of the vegetable that can be used to produce biodiesel due to its high vegetable oil content. This research was conducted to investigate fatty acid characteristics of biodiesel produced from peanut and perfomance of a diesel engine which is fueled by mixture of peanut biodiesel and diesel fuel. Biodiesel was produced by some processes namely degumming, free fatty acid content testing, esterification and transesterification. It was produced 1450 ml biodiesel per 10 kg peanuts. Gas chromatography-mass spectrometry device was used to determine fatty acid content of peanut biodiesel which consists of 52.77% of oleic acid, 16.59% of palmitic acid and 10.63% of behenic acid, respectively. Four mixtures of peanut biodiesel and diesel fuel were created, namely B0 (pure diesel fuel) , B5, B10, B20 where index number is percentage of biodiesel in the mixture. These mixtures were applied to fuel an engine diesel to observe engine perfomances with variation of load and speed on engine. The best engine perfomance result from experiments was found using B20 with spesific fuel consumption (SFC) value is 0.175 kg/kWh at 30 psi of load and 1250 rpm engine speed, the air-fuel ratio (AFR) is 15,26 at 20 psi of load and 1500 rpm engine speed and termal eficiency is 46.37 percent at 30 of load and 1250 rpm engine speed.

Biodiesel Production from Waste Cooking Oil: A Perspective on Catalytic Processes

Presently, the use of fossil fuels is not ecologically sustainable, which results in the need for new alternative energies such as biodiesel. This work presents a review of the classification of the lipidic feedstocks and the catalysts for biodiesel production. It also presents the pros and cons of the different processes and feedstocks through which biodiesel is obtained. In this context, cooking oil (WCO) has emerged as an alternative with a high potential for making the process sustainable. A detected limitation to achieving this is the high content of free fatty acids (FFA) and existing problems related to homogeneous and heterogeneous catalysts. To overcome this, the use of bifunctional catalysts is being evaluated by the scientific community. Thus, this work also explores the advances in the study of bifunctional catalysts, which are capable of simultaneously carrying out the esterification of free fatty acids (FFA) and the triglycerides present in the WCO. For the sake of an improved understanding of biodiesel production, flow diagrams and the mechanisms implied by each type of process (enzymatic, homogenous, and heterogeneous) are provided. This article also highlights some of the challenges in catalyst development for sustainable biodiesel production from low-grade raw materials.

Kinetics of free fatty acids esterification in waste frying oil using novel carbon-based acid heterogeneous catalyst derived from Amazonian Açaí seeds – Role of experimental conditions on a simpler pseudo first-order reaction mechanism

This study reports the kinetics of free fatty acids esterification in waste frying oil, based on a simpler non-conventional pseudo first-order homogeneous reaction mechanism using a highly-efficient acid heterogeneous catalyst derived from seeds of Açaí (Euterpe oleracea Mart.), subjected to changes in temperature, catalyst dosage, MeOH:Oil ratio, and stirring speed. Statistical analyses revealed significant effects all four conditions (p < .05) on the reaction's apparent rate constant (k1) over their different pre-defined levels. Reaction mechanism was inferred to be fundamentally acid ionic exchanges with the oil/water film on catalyst's surface, neglecting kinetically controlled liquid-to-liquid splitting and autocatalyzed esterification.

Box-Behnken Design for Optimization on Esterification of Free Fatty Acids in Waste Cooking Oil Using Modified Smectite Clay Catalyst

A potential alternative fuel option is biodiesel, which is produced mostly from natural resources due to the limited availability of petroleum supplies and environmental issues. Waste cooking oil (WCO) containing a high concentration of free fatty acid (FFA) can be transformed into biodiesel, which substantially benefits the environment and for reducing the fuel . The use of smectite clay as a catalyst in the esterification reaction of WCO with methanol was studied. Smectite was chemically activated by sulfuric acid (H2SO4) to obtain the acid-modified smectite. The utilization of an acid-catalyzed esterification procedure as a pre-treatment for WCO for biodiesel synthesis has been studied in some detail. However, there aren't many effective ways to optimize this operation. The process variables used in this study's esterification of FFAs in WCO were optimized using a Box-Behnken design (BBD). At atmospheric pressure, the catalyst amount of 5.03 wt%, the methanol to WCO molar ratio of 22.38, and the reaction time of 3.01 h are the optimal running parameters for accomplishing 97.96% FFA conversion. The catalyst was employed five times in a row without noticeably lowering its catalytic effectiveness. The results showed that smectite clay is an essential, low-cost, and recyclable catalyst for the esterification of FFA in WCO.

Sustainable Setups for the Biocatalytic Production and Scale-Up of Panthenyl Monoacyl Esters under Solvent-Free Conditions.

A sustainable scaling-up process for the biocatalytic production of new bioactive provitamin-B5 monoacyl esters has been demonstrated. A solvent-free reaction protocol, based on the formation of eutectic mixtures between neat substrates, renders highly efficient direct esterification of free fatty acids (i.e., from C6 to C18 alkyl-chain length) with panthenol catalyzed by lipase. The scale-up from 0.5 to 500 g was evaluated by means of using several reaction systems (i.e., ultrasound assistance, orbital shaking, rotary evaporator, and mechanical stirring coupled to vacuum). For all reactor systems, the yield in panthenyl monoacyl esters was improved by increasing the length of the alkyl chain of the fatty acid (i.e., from 63% yield for panthenyl butyrate to 83% yield for panthenyl myristate). The best results (87-95% product yield, for all cases) were obtained upon a scale-up (50-500 g size) and when a vacuum system was coupled to the biocatalytic reaction unit. Under the optimized conditions, a 5-fold reduction of the amount of biocatalysts with respect to reactors without vacuum was achieved. The recovery and reuse of the immobilized enzyme for five operation cycles were also demonstrated. Finally, different metrics have been applied to assess the greenness of the solvent-free biocatalytic synthesis of panthenyl monoesters here reported.

Synthesis and Characterization of Physically Mixed V2O5.CaO as Bifunctional Catalyst for Methyl Ester Production from Waste Cooking Oil

Synthesis of the solid bifunctional vanadium-calcium mixed oxides catalyst was accomplished by application of a simple physical mixing approach. In this work, we compared the catalytic activity of CaO and 2%V2O5.CaO catalyst. Various characterization methods, such as X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), BET surface area, and temperature-programmed desorption (TPD) of CO2 and NH3, were involved in studying the newly synthesized catalysts. The presence of CaO, CaCO3, and Ca(OH)2 compounds in the synthesized catalyst were detected by XRD and FTIR analysis. The existence of 2% V2O5 on the CaO catalyst surface was demonstrated by XRF analysis. From TPD-NH3, TPD-CO2, and BET surface area analysis, it was known that the 2% V2O5-CaO catalyst had a higher total number of acid-base sites and surface area than the CaO catalyst. In the fatty acid methyl esters (FAME) production from waste cooking oil (WCO) with higher free fatty acid (FFA), CaO could only catalyze the transesterification reaction. In contrast, 2%V2O5-CaO could successfully catalyze both the esterification of FFA and the transesterification of triglyceride (TG) simultaneously in a one-step reaction process. Thus, these results prove that 2%V2O5.CaO can act as a bifunctional catalyst in the production of biodiesel from WCO. Moreover, the synthesized 2%V2O5.CaO catalyst could achieve a maximum FAME yield of 51.30% under mild reaction conditions, including a 20:1 methanol to oil molar ratio, 60 °C reaction temperature, 1 wt% of catalyst loading, and 3 hours of reaction time.

Design of a New Chemoenzymatic Process for Producing Epoxidized Monoalkyl Esters from Used Soybean Cooking Oil and Fusel Oil

The aim of this study was to produce epoxidized monoalkyl esters (EMAE), a valuable class of oleochemicals used in a wide range of products and industries, from used soybean cooking oil (USCO) and fusel oil via a three-step chemoenzymatic process. This process consists of a first enzymatic hydrolysis of USCO to produce free fatty acids (FFA). Here, five microbial lipases with different specificities were tested as biocatalysts. Full hydrolysis of USCO was obtained after a 180 min reaction time under vigorous stirring (1500 rpm) using a non-specific lipase from Candida rugosa (CRL). Then, monoalkyl esters (MAE) were produced via the esterification of FFA and fusel oil in a solvent-free system using the lipase Eversa® Transform 2.0 (ET2.0) immobilized via physical adsorption on poly(styrenene-divinylbenzene) (PSty-DVB) beads as a biocatalyst. Different water removal strategies (closed and open reactors in the presence or absence of molecular sieves at 5% m.m−1) on the reaction were evaluated. Maximum FFA conversions of 64.3 ± 2.3% (open reactor after a 30 min reaction time) and 73.5 ± 0.4% (closed reactor after a 45 min reaction time) were observed at 40 °C, using a stoichiometric FFA:fusel oil molar ratio (1:1), without molecular sieves, and 5 mg of immobilized protein per gram of reaction mixture. Under these conditions, maximum FFA conversion was only 30.2 ± 2.7% after a 210 min reaction time in a closed reactor using soluble lipase. Reusability tests showed better retention of the original activity of immobilized ET2.0 (around 82%) after eight successive batches of esterification reactions conducted in an open reactor. Finally, the produced MAE was epoxidized via the Prilezhaev reaction, a classical chemical epoxidation process, using hydrogen peroxide and formic acid as a homogeneous catalyst. The products were characterized by standard methods and identified using proton nuclear magnetic resonance (1H NMR). Maximum unsaturated bond conversions into epoxy groups were at approximately 33%, with the experimental epoxy oxygen content (OOCexp.) at 1.75–1.78%, and selectivity (S) at 0.81, using both MAEs produced (open or closed reactors). These results show that this new process is a promising approach for value-added oleochemical production from low-cost and renewable raw materials.

Zeolitic imidazolate framework (ZIF-8)-derived acid-base bifunctional single-atom catalysts with Zn-Nx coordination for microalgal lipids conversion

To strengthen active sites in zeolitic imidazolate frameworks (ZIFs) to effectively convert microalgal lipids into biodiesel, acid-base bifunctional single-atom catalysts with Zn-Nx coordination were synthesized through pyrolyzing ZIF-8. The saturated coordinated Zn-N4 sites were destroyed and converted to unsaturated coordinated Zn sites and surrounding N atoms at 700 °C, which enhanced Lewis acidity and basicity, respectively. The Zn-N content in the catalyst decreased from 77.68 % to 43.26 %, while that of pyridinic N increased from 8.14 % to 36.73 %. The acidity of the catalyst increased from 0.498 to 3.979 mmol/g, whereas basicity increased from 0.219 to 0.650 mmol/g. According to density functional theory calculations, unsaturated coordinated Zn-Nx (x = 1, 2, 3) sites exhibited lower free energies and reaction energy barriers in free fatty acid esterification. The energy barriers for rate-determining steps over Zn-N4, Zn-N3, Zn-N2, and Zn-N1 sites were + 1.01 eV, +0.82 eV, +0.63 eV, and + 0.54 eV, respectively. Therefore, the optimum catalyst exhibited a high conversion efficiency of 97.9 %, which was better than that of ZIF-8 (85.4 %).

Encapsulated paracetamol-based eutectic solvents for the treatment of low-grade palm oil mixed with microalgae oil

The development of an efficient and green catalyst is a key step for the esterification of free fatty acid (FFA) in non-edible oil feedstocks. This study introduces a novel acidic deep eutectic solvent (DES) catalyst derived from an active pharmaceutical ingredient for FFA esterification. The DES was formed by paracetamol and p-toluenesulfonic acid monohydrate (PTSA), as the hydrogen bond acceptor (HBA) and the hydrogen bond donor (HBD) components, respectively. The DES was encapsulated in medical capsules for the loading and handling steps; and they utilized to esterify a high content of FFA (8.11%) in a low-grade palm oil-microalgae oil mixture to achieve an acceptable FFA limits (<2%) for transesterification reaction. The FFA content was decreased to < 2% under optimum conditions (catalyst dosage 2% wt/wt of catalyst to oil, 10:1 molar ratio of methanol to oil at 60 °C for 60 min reaction time). Paracetamol forms a eutectic mixture with PTSA and is an effective HBA component in the formation of the DES catalyst. The analysis of relative solubility screening, σ-profile and σ-potential confirm certain level of solubility and homogeneity of this DES in methanol during the pre-treatment process. The formation of the eutectic mixture endows the catalyst with advantages for the esterification reaction such as improvements in recyclability and hygroscopicity of PTSA.

Conversion of Free Fatty Acid in Calophyllum inophyllum Oil to Fatty Acid Ester as Precursor of Bio-Based Epoxy Plasticizer via SnCl2-Catalyzed Esterification.

The preparation and application of bio based plasticizers derived from vegetable oils has gained increasing attention in the polymer industry to date due to the emerging risk shown by the traditional petroleum-based phthalate plasticizer. Epoxy fatty acid ester is among the prospective alternative plasticizers since it is ecofriendly, non-toxic, biodegradable, low migration, and low carbon footprint. Epoxy plasticizer can be synthesized by the epoxidation reaction of fatty acid ester. In this study, the preparation of fatty acid ester as a green precursor of epoxy ester plasticizer was performed via esterification of free fatty acid (FFA) in high acidic Calophyllum inophyllum Seed Oil (CSO) using methanol in the presence of SnCl2.2H2O catalyst. The analysis of the process variables and responses using Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was also accomplished. It was found that the quadratic model is the most appropriate model for the optimization process. The BBD analysis demonstrated that the optimum FFA conversion and residual FFA content were 75.03% and 4.59%, respectively, achieved at the following process condition: a reaction temperature of 59.36 °C, a reaction time of 117.80 min, and a catalyst concentration of 5.61%. The fatty acid ester generated was an intermediate product which can undergo a further epoxidation process to produce epoxy plasticizer in polymeric material production.

Kinetic Parameters Investigation for The Esterification of Free Fatty Acid from Coconut Oil Mill Waste using Montmorillonite-Sulfonated Carbon from Glucose Composite Catalyst

Coconut oil mill waste (CMW) contained high free fatty acid (FFA) content which potentially could be converted into a value-added product such as fatty acid methyl ester (FAME). In this study, a montmorillonite-sulfonated carbon catalyst was used to evaluate the kinetic parameter of FFA conversion from CMW into FAME. The characterization of FTIR and SEM-EDX confirmed that the -SO3H groups were successfully incorporated into montmorillonite- carbon catalyst. The highest catalyst acidity (9.4 mmol/g) was achieved by a ratio of montmorillonite to sulfonated carbon of 1:3 % w/w. The kinetic study using montmorillonite-sulfonated carbon 1:3 % w/w showed that the reaction temperature and molar ratio of methanol to FFA (% v/v) were positively correlated to the reaction rate. The highest rate constant of esterification towards the product (k1), reactant (k2), and equilibrium were 0.1187, 0.0595, and 1.995, achieved by a temperature of 80 ˚C, respectively. The Arrhenius constant and activation energy towards the product were 3.3085×106 and 50.3 J/mole, respectively. The reaction temperature was positively correlated to the equilibrium constant, which indicated that the reaction was endothermic. The kinetic model validation revealed that the predicted value from the model was adequately in accordance with the experimental value, as indicated by a high coefficient of determination.

Volatilome evolution during storage and in vitro starch digestibility of high-power ultrasonication pretreated wholegrain Oryza sativa L.

The potential of high-power ultrasonication (HPU) to enhance the physicochemical stability of bran-containing cereal products has been demonstrated, but the information concerning how the wholegrain volatilome and key quality-related chemical reactions evolve responding to HPU remains scarcely reported. The objective of this work was to examine the headspace volatile fingerprinting features of sonicated wholegrain brown rice (WBR; 400 W, 28 kHz, 30 min) following an accelerated storage testing (37 °C, 20 days), and simultaneously to identify the key chemical reactions induced by ultrasonication. A total of 70 aroma compounds were identified by the untargeted headspace GC–MS, including 9 alkanes, 6 alkenes, 15 aldehydes, 6 furans, 12 ketones, 9 alcohols and 13 miscellaneous compounds. Multivariate statistical analysis demonstrated that HPU pretreatments before a storage process significantly influenced the volatilome evolution, as revealed by a clear classification between sonicated and unsonicated grains. Supervised orthogonal partial least squares discriminant analysis identified the volatiles including acetic acid, pentanoic acid, hexanal, ethyl hexanoate and 2-pentyl-furan as HPU-related markers, inferring that HPU mainly modified the chemical reactions involving lipid decomposition, free fatty acids oxidation and esterification. This was further confirmed by targeted monitoring of lipid peroxidation products, with 13.22–14.84 % of MDA contents reduced (p < 0.05) in sonicated samples after storage. Besides, the ultrasonic effects resulted in a slight improvement of in vitro starch digestibility of WBR samples depending on the rice ecotype. This investigation demonstrated the potential of HPU pretreatments for prolonging the oxidative stability of WBR grains, without significantly compromising digestion properties.

Functionalized mesoporous polymer ionic liquids for efficient immobilization of lipase: Effects of ethyl oleate

Herein, fatty acid esters were synthesized cost-effectively from various fatty acids using reusable lipase (L) immobilized with novel porous ionic polymer (PIP) (l–PIP). The functionalized mesoporous PIP was synthesized through Friedel–Crafts alkylation reaction of 1, 4-bis(bromomethyl) benzene in the presence of ferric chloride as catalyst, and lipase was completely immobilized with PIP at varied time, forming l–PIP–6H, l–PIP–12H, l–PIP–18H, l–PIP–24H, l–PIP–30H, and l–PIP–36H, which were applied in ester production. l–PIP–30H was characterized using FT–IR, SEM, XPS, solid–state 13C NMR, and N2 adsorption–desorption isotherms. The conversion of oleic acid reached 88.21 % under optimized conditions (12:1 ethanol/oleic acid molar ratio after 5 h at 45 °C with 250 wt% catalyst at 300 rpm). The stability and reusability of l–PIP–30H were demonstrated by the sustained catalytic efficiency for at least six reaction cycles. Good catalytic activity during the esterification of various free fatty acids with ethanol was observed. This cost–efficient and effective lipase–immobilized PIP catalyst may have positive economic and environmental repercussions to inspire further academic and industrial research on biodiesel.

DFT Study of the Possible Reaction Path for Radical Promoted Esterification Mechanism of Free Fatty Acids of Soapnut Oil for the Production of Biodiesel

Abstract:Esterification of higher free fatty acids content by using a photo-catalyst has recently been proved as the most efficient method for the pretreatment of non-edible oil to synthesize biodiesel.Methods:In the current study, mechanistic details of photo-catalyzed esterification reaction for four different fatty acids through density functional theory (DFT) calculations are explored and compared with un-catalyzed esterification reaction.Results:Revealed that the presence of photo-catalyst lowers the activation barrier and the structure of fatty acid has no significant effect on its reactivity. Thermodynamic data also revealed that the presence of photo-catalyst lowered the activation energy from 51.67 kcal/mol to 0.7495 kcal/mol. Furthermore, Gibbs free energy changes (ΔrGm Ø) and molar enthalpy changes (ΔrHm Ø) of the photo-catalyzed esterification reaction are negative, indicating that it is a spontaneous exothermic reaction. On the other hand, free fatty acids esterification in the absence of a catalyst is a kinetically unfavorable process with positive values of ΔrGm Ø and ΔrHm Ø.Conclusion:Our findings theoretically clarify the mechanism of the photo-catalyzed esterification reaction of FFA present in non-edible oil, which facilitates the process of biodiesel production.