Glycerolysis Reaction Research Articles

Utilization of Waste Glycerol from Biodiesel Process as a Substrate for Mono-, Di-, and Triacylglycerol Production

Glycerol (or glycerin) is a major by-product in the biodiesel process. Ten percent of crude glycerol are created for every 100 pounds of biodiesel produced. As the utilization of biodiesel increasing, an excess of glycerol is being generated. However, the purify of waste glycerol is expensive, biodiesel producers must search alternative methods for its utilization. This paper demonstrate the feasibility of producing mono-, di- and triacylglycerol from waste glycerol. The acylglycerol was produced through glycerolysis reaction using commercial lipase from Candida sp. Effects of various reaction parameters were evaluated. The optimum conditions for acylglycerol production were a glycerol to fatty acid mole ratio of 6∶1, 100 mg of lipase with the reaction temperature and time at 40°C and 24 h, respectively. Analysis of acylglycerol by Thin Layer Chromatography (TLC) using petroleum ether : diethyl ether :methanol:acetic acid (90:7:2.5:0.5 v/v) as mobile phase found that mono-, di- and triacylglycerol were produced in high purity. Interestingly, the highest production of acylglycerol yeild from commercial lipase and crude lipase from pacific white shrimp’s hepatopancreas were obtained at the same conditions. Attenuated Total Reflectance (ATR)-Fourier Transform Infrared Spectroscopy (FTIR) proved that the final product contains mono-, di- and triacylglycerol.

Theoretical aspects of methyl acetate and methanol activation on MgO(100) and (501) catalyst surfaces with application in FAME production

Density functional theory (DFT) calculations were carried out to study the activation of methyl acetate and methanol on MgO(100) and MgO(501) surfaces and integrated in the context of transesterification, interesterification and glycerolysis reactions used in biodiesel industry. First results indicate the importance of including of dispersion forces in the calculations. On MgO(100) the reverse reactions steps of CO and CH dissociations and on MgO(501) the same reverse reaction step of CH dissociations of methyl acetate are energetically favorable, while the dissociation of CO bond into methoxide and acetate fragments on the edge of MgO(501) was found to be exothermic with a low activation energy. For methanol, the dissociation of OH bond on MgO(100) surface in the presence of the second coadsorbed methanol molecule becomes more energetically favoured compared to the isolated molecule, due to the fact that the methoxide fragment is stabilized by intermolecular hydrogen bonding. This is reflected by the decrease of the activation energy of the forward reaction step and the increase of the activation energy of the backward reaction step, increasing the probability to have dissociated molecules among the undissociated ones. These results represent a step forward for better understanding from atomistic point of view the paths of these reactions on these surfaces for the corresponding catalytic processes.

A highly efficient immobilized MAS1 lipase for the glycerolysis reaction of n-3 PUFA-rich ethyl esters

This study reported that immobilized MAS1 lipase showed high catalytic efficiency in the production of triacylglycerols (TAG) highly enriched with n-3 polyunsaturated fatty acids (PUFA) by glycerolysis of ethyl esters (EE). Immobilized MAS1 lipase was found to have no regiospecificity and be a more suitable catalyst for the glycerolysis of n-3 PUFA-rich EE compared with other enzymes. Higher TAG content (73.9%) and EE conversion (82%) were obtained by immobilized MAS1 lipase than those by Novozym 435 (29.6% and 54.8%, respectively) and Lipozyme RM IM (10% and 49%, respectively). Besides, the effects of temperature, enzyme loading and n-3 PUFA-rich EE/glycerol molar ratio on TAG content were evaluated using response surface methodology. The results showed that temperature, enzyme loading and n-3 PUFA-rich EE/glycerol molar ratio had significant effects on TAG content. The maximum TAG content (76.5%) was achieved under the optimal conditions (enzyme loading of 163.8U/g substrate, n-3 PUFA-rich EE/glycerol molar ratio of 4.13:1 at 65°C). Subsequently, the glycerolysis reaction mixtures were further purified by molecular distillation and highly pure n-3 PUFA-rich TAG (96.2%) with similar fatty acids composition to the substrate (EE) was obtained in the final products. In addition, the obtained final products had low acid value and peroxide value (0.03mg KOH/g and 3.2meq/kg, respectively). These results indicated that immobilized MAS1 lipase is a promising catalyst for the synthesis of TAG in industrial application.

Viable Glycerol Carbonate Synthesis Through Direct Crude Glycerol Utilization from Biodiesel Industry

Synthesis of organic carbonates specifically glycerol carbonate has become a major concern among researchers due to its interesting chemical properties. In this study, we report the direct utilization of two different sources of crude glycerol in glycerolysis reaction with urea for the synthesis of glycerol carbonate using potassium silicate containing boiler ash as a catalyst. The level of interference of moisture and methanol content in crude glycerol was studied by mimicking conditions in pure glycerol and it was found that moisture at 10 wt% significantly effects the conversion of glycerol while methanol at 5 wt% affects the selectivity towards glycerol carbonate. However, due to the low moisture and methanol content in crude glycerol, comparable yield % of glycerol carbonate with commercial pure glycerol as starting feedstock was noted. Besides, the study also found that the potassium methylate and sodium methylate used as catalysts for the commercial production of biodiesel can be also used as an effective catalyst for the synthesis of glycerol carbonate. The current approach is a near approach for a greener environment which proposes use of both catalyst and glycerol derived from waste sources.

Promotional Effects of CeO2 on Stability and Activity of CaO for the Glycerolysis of Triglycerides

Glycerolysis of triglycerides (corn oil) was carried out over CeO2 promoted CaO catalysts. CeO2 was introduced into CaO via the sol–gel combustion method with citrate as the precipitator. A strong interaction between CaO and CeO2 was revealed by XRD, XPS and Raman results, which results in an increased basic strength and amounts of strong basic sites. Moreover, the lixiviation of CaO in the glycerol at high temperature, which is the key problem in the glycerolysis reaction over CaO-based catalysts, was inhibited significantly. XRD, N2 adsorption–desorption isotherms and SEM results exhibit introducing CeO2 increases the surface area, pore volume and pore size of CaO catalysts, which are beneficial to the catalytic activity. The 2CaO–1CeO2 catalyst with strong basicity and large surface area achieved over 90 % conversion after 1 h while the lixiviated Ca decreased dramatically.

Lipase-catalyzed glycerolysis of olive oil in organic solvent medium: Optimization using response surface methodology

Enzymatic glycerolysis of olive oil for mono- (MG) and diglycerides (DG) synthesis was investigated. Several pure organic solvents and co-solvent mixtures were screened in a batch reaction system. The yields of MG and DG in co-solvent mixtures exceeded those of the corresponding pure organic solvents. Batch reaction conditions of the glycerolysis reaction, the lipase amount, the glycerol to oil molar ratio, the reaction time, and temperature, were studied. In these systems, the high content of reaction products, especially MG (55.8 wt%) and DG (16.4wt%) was achieved at 40 °C temperature and 0.025 g of lipase with relatively low glycerol to oil molar ratio (2: 1) within 4 h of reaction time in isopropanol/tert-butanol (1: 3) solvent mixture. Glycerolysis reaction was optimized with the assistance of response surface methodology (RSM). Optimal condition for reaction conversion was recommended as lipase amount 0.025 g, glycerol to oil molar ratio 2: 1, reaction time 4 h and temperature 40 °C.

Polycarbonate Waste Management using Glycerol

Recycling method of polycarbonate (PC) plastic using glycerol is proposed as a novel green method. Glycerol was found as an efficient reagent for chemical recycling of PC and gives upto 98% monomer recovery, which is compatible with any of existing chemical recycling methods. Recycling involves digestion followed by glycerolysis reaction of PC. The various products thus obtained are Bisphenol A (BPA); mono glycerol ether of BPA and di glycerol ether of BPA. Addition of urea improves the yield toward more alkoxylated products, controls the dehydration of glycerol to acrolein at reaction temperature and improves the application of glycerol as a reagent. Temperature programmed FTIR spectra study provides a mechanistic picture of the proposed chemical recycling. Glycerol carbonate and glycerol urethane was found as the important reaction intermediates. The process works well with industrial grade glycerol to improve the economy in this process. Furthermore, a working model of the recycling of post-user optical disc is also proposes.

Enzymatic Synthesis of Mono- and Diglyceride Using Lipase From Candida rugosa Immobilized Onto Cellulose Acetate-Coated Fe2O3 Nanoparticles

A lipase from Candida rugosa was covalently immobilized on the cellulose acetate (CA)-coated Fe2O3 nanoparticles for the biocatalysis applications. The characterization of the Fe2O3-CA particles before and after immobilization of lipase was studied. The biocatalyst was assayed for the glycerolysis of olive oil in solvent system. The effect of reaction time, temperature, molar ratio of glycerol to oil and amount of lipase on the glycerolysis reaction was investigated. Results showed that the high yield of monoglycerides (49.7 wt%) and diglycerides (17.4 wt%) was achieved at 40 °C temperature and 0.02 g of lipase with relatively low glycerol to oil molar ratio (2:1) within 4 h of reaction time. Kinetics of immobilized lipase followed Lineweaver–Burk model with lower K m and V max values when compared to the free lipase. The immobilized lipase showed higher activity, thermal stability and reusability compared to the free lipase.

A First Attempt into the Production of Acylglycerol Mixtures from Echium Oil.

Enzymatic glycerolysis of Echium oil (Echium plantagineum) has been carried out in the presence of four commercial lipases. Different pretreatments of the reaction mixture, such as high pressure homogenization and addition of food grade monoolein as an emulsifier, were evaluated to test their influence on the glycerolysis reaction. In addition, the impact of reducing temperature and the utilization of a solvent generally recognized as safe as a flavoring agent, such as limonene, were also investigated. Conversion of ca. 60–70% of triacylglycerols and production of ca. 25–30% of monoacylglycerols (MAGs) were attained. Finally, at the best reaction conditions, the glycerolysis reaction was scaled up at pilot plant and the product mixture obtained was fractionated via molecular distillation. From this stage, two products were attained: a distillate containing 80% of MAGs and a residue containing approximately 50% of diacylglycerols and 50% of triacylglycerols. All these mixtures can be utilized as self-emulsifying vehicles for the formulation of bioactive substances and also as precursors for the production of structured bioactive lipids.

Synthesis and copolymerization of thermosetting resins obtained from vegetable oils and biodiesel-derived crude glycerol

Alkaline crude glycerol from biodiesel production was used in the synthesis of soybean oil and castor oil-based polyols through glycerolysis reaction. These polyols were further converted into highly active unsaturated resins through maleinization reactions. The resins were copolymerized with styrene (10–50wt%) using cobalt octoate and methyl ethyl ketone peroxide (MEKP) at 40°C, affording rigid materials. Materials were characterized by FTIR spectroscopy, Soxhlet extraction, TGA, DMTA, and mechanical tests. Tg values of 72–152°C and elastic modulus of 465–2945MPa were obtained, depending on the type of resin and styrene concentration.The materials presented flexural modulus and flexural strengths in the range of 246–1716MPa and 24–89MPa respectively. Tg values and elastic modulus at 25°C were higher for materials obtained from castor oil glycerides. Materials obtained from both resins were stable under 200°C. Higher thermal stabilities were obtained for castor oil based materials. These properties were related to a higher crosslinking density obtained for polymers derived from castor oil. In addition, radical homopolymerization of both resins at 100°C during 24h afforded viscous liquids with Mn values between 1358 and 3775.

Glycerolysis of methyl oleate on MgO: Experimental and theoretical study of the reaction selectivity

The liquid-phase MgO-promoted glycerolysis of methyl oleate, a fatty acid methyl ester (FAME), to give acylglycerol products was studied both, experimentally and by density functional theory (DFT). Catalytic results showed that strongly basic low coordination O2− surface sites participate in kinetically relevant steps of the glycerolysis reaction. Changes in the selectivity toward the different mono- and diglyceride isomers were investigated by varying the reaction conditions. The main product was always α-glyceryl monooleate (α-MG), a monoglyceride with the ester fragment at one of the terminal positions of the glycerol molecule; the β-MG isomer, with the ester substituted at position 2 was obtained in much lower amounts.The molecular modeling of glycerol (Gly) and FAME adsorptions as well as of the glycerolysis reaction was carried out using periodic DFT calculations and a model of stepped MgO surface. Results indicated that FAME was more weakly adsorbed than Gly; the latter adsorbs on a coordinatively unsaturated surface O2− site with OH bond breaking at position 2 of the Gly molecule, giving therefore a surface β-glyceroxide species. Calculations explained the apparent contradiction between the preferential formation of the α-MG isomer and the energetically favored dissociation of the secondary OH group of Gly that leads to the β-glyceroxide species. They predict that the β-glyceroxide species participates in the pathways conducting to both, α- and β-MG isomers. Synthesis of α-MG occurs by CO coupling of β-glyceroxide with FAME at one of the two primary OH groups of the β-glyceroxide species. Two transition states (TS) and a tetrahedral intermediate (TI) are involved in both, α-MG and β-MG isomer formation. However, the pathway toward β-MG is limited by the large sterical effects associated to the TI formation. Contrarily, the TI leading to α-MG is relatively easy to form.

Response surface methodology for optimizing the glycerolysis reaction of olive oil by Candida rugosa lipase

In the present work, solvent free olive oil glycerolysis for the monoglycerides (MG) and diglycerides (DG) production with an immobilized Candida rugosa lipase was studied. MG and DG production were optimized using experiment design techniques and response surface methodology (RSM). RSM based on five-level, a five-variable central composite design (CCD) was used to optimize MG and DG production: reaction time, temperature, molar ratio of glycerol to oil, amount of lipase, and water content in glycerol. The reaction time, temperature, and amount of lipase were observed to be the most significant factors on the process response. The immobilized Candida rugosa lipase revealed optimum yield of MG and DG as 38.71 and 40.45 wt% respectively following a 5h reaction time with 0.025 g of lipase and 5% water content in glycerol at 40?C temperature. The yield of MG and DG production can be enhanced 1.5 fold by RSM.

Enzymatic glycerolysis for conversion of sunflower oil to food based emulsifiers

High temperature glycerolysis widely used in industrial scale for production of food-based emulsifiers has many disadvantages. On the other hand, high cost, unavailability, low activity and high reaction time of enzymes limit the use in industrial scale glycerolysis reactions for the production of food-based emulsifiers (i.e. monoglycerides). The goal of this project is to develop an efficient and optimal glycerolysis process for production of monoglycerides. This study found that optimal production through enzymatic glycerolysis was achieved with 15wt% loading of Fermase CALB 10000 and oil to glycerol molar ratio was optimized at 1:5. A tert-butyl alcohol system was developed carefully with evaluation of more than 10 organic solvents. The suitable co-solvent addition was 1:50 molar ratio with respect to oil. In the above-optimized condition, the conversion of monoglyceride was 50–60% at 2–3h and 70–80% at 5 to 6h of reaction time. The reaction time was optimized at 5h. Subsequent to the following reaction was found that, there is no drastic reduction of enzyme activity and could be reused for next reaction. Due to this behaviour, we recommend Fermase 10000 as an effective and low cost enzyme for future glycerolysis reaction in industrial scale.

Intensification of glycerolysis reaction of higher free fatty acid containing sustainable feedstock using microwave irradiation

Glycerolysis can be a useful alternative for the removal of free fatty acid content present in the sustainable feedstock but has limitation in terms of requirement of higher temperatures and higher processing time. In the present work, intensification of glycerolysis has been attempted using microwave irradiations with comparative studies based on the use of the conventional heating approach. Effect of reaction parameters such as molar ratio (oil to glycerol), catalyst concentration and reaction temperature has been investigated. It has been observed that the optimum molar ratio of oil to glycerol as 1:2 and catalyst concentration of 0.1% for both approaches is similar but there is a significant decrease in the reaction time and optimum temperature. Reaction time was reduced from 240 to 25min while the optimum temperature for maximum benefits reduced from 200 to 105°C for the microwave based approach. Comparison based on kinetic analysis confirmed that the rate constant obtained for microwave assisted glycerolysis was six times higher than that obtained in the conventional approach. Energy consumption analysis also revealed the superiority of microwave based synthesis approach with much lower energy requirement for microwave (35.3kJ/g) as compared to the conventional method (203.6kJ/g).

High yield of monoacylglycerols production through low‐temperature chemical and enzymatic glycerolysis

AbstractThe present study aimed to produce MAG through low‐temperature chemical glycerolysis. Over 80% MAG yield with 97% TAG conversion was obtained within short reaction times at temperature of 35–55°C, when tert‐butanol (TB) or tert‐pentanol (TP) was used as reaction medium and sodium hydroxide (NaOH) as catalyst. TB gave a faster reaction rate than TP. Catalysts were important for the low‐temperature chemical glycerolysis reaction. Of the eight common base catalysts evaluated, only NaOH and potassium hydroxide (KOH) were effective, and NaOH was better than KOH. Reaction parameters were studied and optimized. The optimum conditions were TB dosage 3:1 (TB to oil in weight ratio), NaOH concentration 0.45 wt% based on oil, molar ratio of glycerol to oil 5:1. Under these conditions, similar MAG yield and TAG conversion was also observed by Novozym 435 catalyzed glycerolysis, however, a 4 h reaction was required.Practical applications: The process of NaOH catalyzed chemical glycerolysis for MAG production in TB solvent system described in this study provides several advantages including short reaction time and high product yield, which is potential for industrial considerations.

Thermal esterification of cinnamic and p-methoxycinnamic acids with glycerol to cinnamate glycerides in solventless media: A kinetic model

The thermal processes of the esterification of glycerol with cinnamic acid and with p-methoxycinnamic acid in the absence of organic solvents to obtain monocinnamoyl glycerols were studied. Esterification runs were performed batchwise, changing the initial molar ratio of acid to glycerol from 1:3 to 1:9, and temperature from 150 to 200°C. Under such conditions, systems proved to be monophasic, obtaining almost quantitative acid conversion and a significant selectivity to monoesters (80–90%). Apart from the esterification reactions, experimental conditions and data suggest the presence of glycerolysis and disproportionation reactions. Several kinetic models were fitted to experimental data and statistical and physical criteria were used to select the most adequate: a model with esterification and reversible glycerolysis reactions. When results and parameter values for both acids were compared, their kinetic behaviour in these processes resulted similar in the experimental conditions tested.

Optimization of structured diacylglycerols production containing ω-3 fatty acids via enzyme-catalysed glycerolysis of fish oil

The main objective of the present work was the production of structured diacylglycerols (DAG) by Novozym 435-catalysed glycerolysis of n-3 PUFA rich fish oil. Different enzyme loads (5, 7, 10, 13 and 15 %, with respect to the total weight of substrates), temperatures (40, 44, 50, 56 and 60 °C) and molar ratios of substrates (1, 1.4, 2, 2.6 and 3, oil/glycerol) were explored by the response surface methodology in order to optimize the reaction system. Temperature showed the highest significant effect (P < 0.05) on the glycerolysis reaction. Good agreement on the experimental data and the second-order polynomial regression was obtained (R2 = 0.85). Optimal conditions for the production of DAG were established by the model using 15 % enzyme load at 60 °C for a 2:1 (oil/glycerol) substrates molar ratio, reaching a 50 % yield, with 89.37 % n-3 PUFA content, namely, EPA (11.32 %), DPA (8.34 %) and DHA (69.71 %).

Evaluation of the use of surfactants as additives in enzymatic glycerolysis reactions

AbstractMAGs and DAGs are widely used as emulsifiers in many industries. During glycerolysis reactions for their production, the immiscibility of the glycerol and the oil phases is an important drawback for practical purposes. For overcoming this problem, the use of a food grade surfactant can be an important alternative to improve system homogeneity, leading to high TAGs conversion in short reaction times. On the other hand, food grade surfactants have bonds that could be modified by lipases. The main interest of this work was to qualitatively verify the reactivity of different Tween and soy lecithin used as additives in glycerolysis reactions in the presence of Candida antarctica B lipase. The biocatalyst had activity toward all tested surfactants in the experimental conditions chosen for the tested reactions. Despite this, MAG and DAG could be produced when using Tween 85 as additive in the enzymatic glycerolysis of fish oil. Our results therefore suggest that tested Tween and soy lecithin can be used as surfactants in glycerolysis reactions, but one has to consider their reactivity in the presence of lipases.Practical applications: This work investigates the reactivity of synthetic (Tween) and natural (soy lecithin) surfactants in the presence of lipase during glycerolysis reactions. Tween 85 was further applied in different reaction media for a better understanding of the modifications it was undergoing. The biocatalyst had activity toward almost all tested surfactants in the experimental conditions chosen for the preliminary assays herein performed, as qualitatively verified by thin‐layer chromatography. This result suggests that the use of phosphatides and polyoxyethylene esters as additives in glycerolysis systems has to be well evaluated as their enzymatic modification may generate problems during downstream processes for the recovery of the desirable products. The present report is part of a broader project aiming at building a platform to allow developing new processes for the production of emulsifiers through enzyme‐catalyzed glycerolysis reaction.

The Production, Benefits, and Applications of Monoacylglycerols and Diacylglycerols of Nutritional Interest

In light of the increasing interest in the development of functional food, several researches have focused on the production of food grade emulsifiers of nutritional interest, especially enriched in the eicosapentaenoic (EPA) and docosahexaenoic acids (DHA). The aim of this paper is to make a review of the production of monoacylglycerols (MAG) and diacylglycerols (DAG) obtained from different feedstock, mainly fish oil. A section of this paper is dedicated to the raw materials used as feedstock for these emulsifiers production. The health benefits of these partial acylglycerols are outlined. The chemical and enzymatic methods for producing these esters of glycerol are discussed, focusing on glycerolysis reactions. Recent advances on the lipase-catalyzed production of these partial acylglycerols in alternative reaction media and systems are also reviewed.

Optimal conditions for the production of monoacylglycerol from crude palm oil by an enzymatic glycerolysis reaction and recovery of carotenoids from the reaction product

SummaryMonoacylglycerol (MAG) was produced from crude palm oil (CPO) by the enzymatic glycerolysis reaction in organic solvents. The optimal conditions for MAG production from CPO were: the use of a mixture of tert‐butanol and hexane (1:1) as the organic solvents; an immobilised lipase of 40%; a molar ratio of glycerol to CPO of 8:1 with 4% of water content in the glycerol; and an initial CPO concentration of 10%. A maximum yield of 74.3% MAG was obtained with an initial production rate of 42.3 mg MAG mL−1 h−1. By converting CPO to the more polar MAG, the efficiency of recovery of carotenoids by adsorption column chromatography was improved up to 75.7% from 55.1% when using unconverted CPO. This study provides information that will be useful for developing an efficient and cheaper industrialised process for the production of MAG from CPO and recovery of carotenoids from the reaction product.