Article

Influence of Mass Transfer on the Production of Biodiesel

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Abstract

The growing interest in alternative fuels makes it important to optimize classical routes for the production of biodiesel, as well as to explore and introduce non-classical alternatives. For the investigations reported in this article, a two-phase system consisting of rape oil and methanol was chosen. The goal of the experiments was to investigate whether ultrasound had a significant influence on the conversion rate of the reaction and the reaction mechanism, or if more intensive mixing of the reaction mixture was required to cause an increase reactivity.

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... Comparing methanolysis of vegetable oil in the presence of low-frequency ultrasound and mechanical agitation at room temperature [4,5] showed that ultrasonic irradiation ensured a shorter reaction time at lower quantity of the catalyst. Lifka and Ondruschka [6] performed the NaOH-catalyzed methanolysis of rapeseed oil at 45°C and observed no significant influence of the mixing method on the reaction rate and the biodiesel yield. This discrepancy might be caused by different types of ultrasonic reactors and different reaction conditions applied. ...
... The fatty acid methyl esters (FAME) formed under ultrasonic irradiation were identical to those formed in the stirred reactor [7], but the rate-determining reaction switches from the conversion of diglycerides (DG) to monoglycerides (MG) in the stirred reactor to the conversion of MG to FAME under ultrasonic irradiation [8]. The use of ultrasound has an extra advantage as it requires one-third to a half of the energy that is consumed by mechanical agitation [3,6]. Singh et al. [9] also observed an optimum input energy (between 125 and 215 kJ) for KOH-catalyzed soybean oil methanolysis using low-frequency ultrasound, ensuring FAME yields higher than 97% in 5 min. ...
... By increasing the catalyst loading, FAME yield and reaction rate also increase [12], but the excess catalyst will negatively affect FAME yield [5,10,14,27]. The reaction in the presence of NaOH at the concentration of 1.0% [6], 1.5% [4,5] or 2.5% [14,27] was followed by the strong soap formation, decreasing the FAME yield. The reaction temperature of base-catalyzed methanolysis in the presence of low-frequency ultrasound has not been optimized yet. ...
Article
The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at different reaction conditions. A full factorial experiment 33with replication was performed. The effects of three reaction variables, methanol-to-oil molar ratio, catalyst loading and the reaction temperature on fatty acid methyl ester yield were evaluated by the analysis of variance and the multiple regression. At the 95% confidence level all three factors and the interaction of the reaction temperature and methanol-to-oil molar ratio were effective on fatty acid methyl ester formation, the most important factor being the catalyst loading. The relationship between the factors and their interactions was modeled by the second-order polynomial equation.
... LFU energy improves the mass transfer between the immiscible reactants via ultrasonic cavitation. It is not only efficient and time saving but also economically viable as it requires low quantity of catalyst [10] and only one-third to a half of the energy that is consumed by mechanical agitation [11][12][13]. Maximizing the interfacial surface area between the immiscible reactants at lower energy inputs than conventional stirred reactors, ultrasonic reactors might be attractive for improving the performance of the transesterification process by obtaining higher biodiesel yields within shorter reaction times. Since the energy required for the biodiesel production represents a significant part of the overall energy input, the use of ultrasonic reactors with better performances than currently employed can reduce the production cost, enhancing chances for large-scale commercialization of the biodiesel production. ...
... With increasing alcohol-to-oil molar ratio from 5/1 to 10/1, the yield was increased from about 91% in 3 h to about 98% in 2 h. Lifka and Ondruschka [13] reported a very low methyl ester yield in 3 h of p-toluenesulfonic acid-catalyzed methanolysis of rapeseed oil. Deshmane et al. [34] carried out acid-catalyzed methanolysis of palm fatty acid distillate (PFAD), a side streaming product of palm oil production, under ultrasonic irradiation. ...
... Many researchers have succeeded in speeding up the reaction rate by carrying out homogeneous base-catalyzed methanolysis in the presence of LFU, for instance, Georgogianni et al. [23,24], Ji et al. [12], Lifka and Ondruschka [13], Siatis et al. [25], Stavarache et al. [10,44,45], etc. The effect of high-frequency ultrasound on the biodiesel production from soybean oil using methanol and potassium hydroxide as catalysts has been studied only by Mahamuni and Adewuyi [46,47]. ...
Article
In the present paper state-of-the art and perspectives of ultrasound-assisted (UA) biodiesel production from different oil-bearing materials using acid, base and enzyme catalysts are critically discussed. The ultrasound action in biodiesel production is primarily based on the emulsification of the immiscible liquid reactants by microturbulence generated by radial motion of cavitation bubbles and the physical changes on the surface texture of the solid catalysts generating new active surface area. The importance of ultrasound characteristics and other process variables for the biodiesel yield and the reaction rate is focused on. UA transesterification is compared with other techniques for biodiesel production. Several different developing methods reducing the biodiesel production costs such as the optimization of process factors, the development of the process kinetic models, the use of phase transfer catalysts, the application of the continuous process, the design of novel types of ultrasonic reactors and the in situ ultrasound application in transesterification of oily feedstocks are also discussed.
... Increasing the molar ratio of methanol/oil beyond 6:1 neither increases the product yield nor the ester content, but rather makes the ester recovery process complicated and raised its cost. Lifka and Ondruscka (Lifka 2004) said that since basic transesterification showed no significant temperature dependence, energy required for thermo starting the reaction mixture can be saved. From the energy balance of the three mixing methods (magnetic stirrer, ultrasound and ultra turrax) employed, it was determined that energy costs are lower for ultrasonic mixing. ...
... So no significant influence due to the mixing method was observed. Percent conversion to ester values is higher than those of Lifka and Ondruscka [26] who reported more than 85% conversion of rapeseed oil to methyl esters after 10 min. at 45 ْ◌C, on the alkaline transesterification of rapeseed oil using NaOH at a concentration of 1 % w/w, using different mixing methods (magnetic). ...
Article
The application of ultrasound during extraction and trans-esterification of oil from rapeseed was evaluated. Two methods of extraction were used, batch-wise extraction and soxhlet extraction. In batch-wise extraction procedure, ground rapeseeds were added to solvent and ultra-sonicated either by cleaning bath or ultrasonic generator. Conventional soxhlet extraction assisted in the soxhlet chamber by ultrasound has been developed. Ultrasonic technique reduced time required to extract oil. Using batch wise extraction procedure, percent recovery of oil increased almost 17.83% and 20.99% by using cleaning bath and ultrasonic generator respectively rather than control after 2hrs.While in using soxhlet extraction percent recovery reached 85% after 1.5 hr in case of ultrasonic and after 4 hrs without using ultrasonic. Physical and chemical properties of rapeseed oil were tested. Then the alkaline trans-esterification of rapeseed oil with methanol and potassium hydroxide for production of biodiesel was studied, using ultra-sonication and magnetic stirring. In trans-esterification the use of ultra-sonication and magnetic stirring led to similar high yields of 90% of methyl esters after approximately 10 min. of reaction time. Comparison between biodiesel obtained and standard biodiesel and diesel fuel was done.
... The use of ultrasound technology in biodiesel production presents an efficient, swift and economically functional process with reduced reaction time, static separation time as well as generally higher yields over the conventional process [38,40]. The effects of use of mechanical stirring, ultrasound technology and hydrodynamic cavitation on soybean biodiesel yields were studied under the following parameters (catalyst, KOH; feedstock, soybean oil; solvent, methanol; alcohol/oil molar ratio of 6:1, temperature of 45°C) by Lifka et al. [41] and Ji et al. [38]. Results obtained showed that the application of ultrasound technology enabled faster reaction periods and higher yields in comparison to mechanical stirring. ...
... Figure 1 shows a schematic of biodiesel production using ultrasound technology. Production of biodiesel under the ultrasonic processing possess the following advantages, reduction in processing time, less amount of alcohol, minimal catalyst, faster separation time and reduced reaction temperature as revealed in several studies [37][38][39][40][41][42][43]. ...
Chapter
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The importance and relevance of generating liquid fuels from biomass and producing biodiesel from vegetable oils given the enormous environmental advantages the process offers cannot be overemphasized. The increasing popularity of biodiesel has generated a great demand for successful commercial production methods, which, in turn, calls for the development of technically and economically sound process technologies. The applicability of various technologies employed currently for biodiesel production under diverse catalytic and process systems is explored, with particular attention paid to sustainable protocols for sub-Saharan Africa
... The collapse of cavitation bubbles disrupts the phase boundary in a two-phase liquid system and causes emulsification by ultrasonic jets that impinge one liquid in to the other [11]. This effect can be employed for biodiesel production [10,[12][13][14]. ...
... In this case ultrasonication increased conversion of oil to methyl esters. Lifka and Ondruscka [13] studied the effect of ultrasonication versus mechanical stirring on the alkaline transesterification of rapeseed oil using NaOH at a concentration of 0.5% w/w at 45°C. A conversion of 80-85% was obtained for both ultrasonicated and mechanically stirred reactions after 30 min. ...
Article
Full-text available
In the present work the alkaline transesterification of sunflower seed oil with methanol and ethanol, for the production of biodiesel fuel was studied. Both conventional and in situ transesterification were investigated using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm). Use of ultrasonication in conventional transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Use of ultrasonication in conventional transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ transesterification the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol use of ultrasonication led to high ester yields (98%) in only 40 min of reaction time while use of mechanical stirring gave lower yields (88%) even after 4 h of reaction time. In situ transesterification gave similar ester yields to those obtained by conventional transesterification being an alternative, efficient and economical process. In all cases a concentration of 2.0% NaOH gave higher ester yields. Reaction rate constants were calculated, using first order reaction kinetics, to be equal to 3.1 × 10− 3 s− 1 for conventional transesterification using methanol and 2.0% NaOH, and 9.5 × 10− 4 s− 1 using ethanol.
... Increasing the molar ratio of methanol/oil beyond 6:1 neither increases the product yield nor the ester content, but rather makes the ester recovery process complicated and raised its cost. Lifka and Ondruscka (Lifka 2004) said that since basic transesterification showed no significant temperature dependence, energy required for thermo starting the reaction mixture can be saved. From the energy balance of the three mixing methods (magnetic stirrer, ultrasound and ultra turrax) employed, it was determined that energy costs are lower for ultrasonic mixing. ...
... So no significant influence due to the mixing method was observed. Percent conversion to ester values is higher than those of Lifka and Ondruscka [26] who reported more than 85% conversion of rapeseed oil to methyl esters after 10 min. at 45 ْ◌C, on the alkaline transesterification of rapeseed oil using NaOH at a concentration of 1 % w/w, using different mixing methods (magnetic). ...
Article
Full-text available
The application of ultrasound during extraction and trans-esterification of oil from rapeseed was evaluated. Two methods of extraction were used, batch wise extraction and soxhlet extraction. In batch wise extraction procedure, ground rapeseeds were added to solvent and ultra-sonicated either by cleaning bath or ultrasonic generator. Conventional soxhlet extraction assisted in the soxhlet chamber by ultrasound has been developed. Ultrasonic technique reduced time required to extract oil. Using batch wise extraction procedure, percent recovery of oil increased almost 17.83% and 20.99% by using cleaning bath and ultrasonic generator respectively rather than control after 2hrs.While in using soxhlet extraction percent recovery reached 85% after 1.5 hr in case of ultrasonic and after 4 hrs without using ultrasonic. Physical and chemical properties of rapeseed oil were tested. Then the alkaline trans-esterification of rapeseed oil with methanol and potassium hydroxide for production of biodiesel was studied, using ultra-sonication and magnetic stirring. In trans-esterification the use of ultra-sonication and magnetic stirring led to similar high yields of 90% of methyl esters after approximately 10 min. of reaction time.
... Comparing the findings of the current study to those of Stavarache et al. [61] (i.e. 95% after 10 min at 30°C using ultrasonication (28 kHz)), indicate a low yield but when compared the yield (88.4%) with those of Lifka and Ondruscka [62] (80-85%) who compared ultrasonication versus mechanical stirring using alkaline transesterification of rapeseed oil at temperature of 45°C in 30 min, it can be realized that the optimum yield in this study was higher. ...
Article
Full-text available
The aim of this study is to investigate modified TiO2 doped with C4H4O6HK as heterogeneous solid base catalyst for transesterification of non-edible, Silybum marianum oil to biodiesel using methanol under ultrasonication. Upon screening the catalytic performance of modified TiO2 doped with different K-compounds, 0.7 C4H4O6HK doped on TiO2 was selected. The preparation of the catalyst was done using incipient wetness impregnation method. Having doped modified TiO2 with C4H4O6HK, followed by impregnation, drying and calcination at 600°C for 6h, the catalyst was characterized by XRD, FTIR, SEM, BET, TGA, UV and the Hammett indicators. The yield of the biodiesel was proportional to the catalyst basicity. The catalyst had granular and porous structures with high basicity and superior performance. Combined conditions of 16:1 molar ratio of methanol to oil, 5 wt.% catalyst amount, 60°C reaction temperature and 30min reaction time was enough for maximum yield of 90.1%. The catalyst maintained sustained activity after five cycles of use. The oxidative stability which was the main problem of the biodiesel was improved from 2.0h to 3.2h after 30days using ascorbic acid as antioxidant. The other properties including the flash point, cetane number and the cold flow ones were however, comparable to international standards. The study indicated that Ti-0.7-600-6 is an efficient, economical and environmentally, friendly catalyst under ultrasonication for producing biodiesel from S. marianum oil with a substantial yield.
... PTSA was added into the preheated SPO at different dosages in presence of methanol to reduce FFA of SPO by converting the FFA to FAME. The mechanism for the acid esterification reaction is shown in Figure 1 [9]. Several batch esterification process were carried out to study the influence of PTSA dosages (0.25-10% wt/wt), molar ratio of methanol to SPO (6:1-20:1), reaction temperature (40-80 o C), and reaction time (30-120 min). ...
Article
Full-text available
Sludge palm oil (SPO) is an attractive feedstock and a significant raw material for biodiesel production. The use of SPO can lower the cost of biodiesel production significantly. In this study biodiesel fuel was produced from SPO by esterification process using P-toluenesulfonic acid (PTSA) as acid catalyst in different dosages in presence of methanol to convert free fatty acid (FFA) to fatty acid methyl ester (FAME). Batch esterification process of SPO was carried out to study the influence of PTSA dosage (0.25-10% wt/wt), molar ratio of methanol to SPO (6:1-20:1), temperature (40-80 o C), reaction time (30-120 min). The effects of those parameters on the yield of crude biodiesel and conversion of FFA to FAME were monitored. The optimum condition for batch esterification process was 0.75% wt/wt, 10:1 molar ratio, 60 o C temperature and 60 minutes reaction time.
... These effects can strongly improve enzymatic reactions [8,9] or contribute to enzyme deactivation [10]. Besides, ultrasound uses only one-third to a half of the energy that is consumed by mechanical agitation [11][12][13]. Some advantages of the ultrasound in enzyme-catalyzed reactions may be summarized as: minimization of the reaction time, reduction of the reagent amounts, yield increasing, and the chemo-, regioand stereoselectivities of reactions that normally would not occur in normal conditions. ...
Article
Full-text available
The named "green chemistry" has been receiving increasing prominence due to its environmentally friendly characteristics. The use of enzymes as catalysts in processes of synthesis to replace the traditional use of chemical catalysts present as main advantage the fact of following the principles of the green chemistry. However, processes of enzymatic nature generally provide lower yields when compared to the conventional chemical processes. Therefore, in the last years, the ultrasound has been extensively used in enzymatic processes, such as the production of esters with desirable characteristics for the pharmaceutical, cosmetics, and food industry, for the hydrolysis and glycerolysis of vegetable oils, production of biodiesel, etc. Several works found in the open literature suggest that the energy released by the ultrasound during the cavitation phenomena can be used to enhance mass transfer (substrate/enzyme), hence increasing the rate of products formation, and also contributing to enhance the enzyme catalytic activity. Furthermore, the ultrasound is considered a "green" technology due to its high efficiency, low instrumental requirement and significant reduction of the processing time in comparison to other techniques. The main goal of this review was to summarize studies available to date regarding the application of ultrasound in enzyme-catalyzed esterification, hydrolysis, glycerolysis and transesterification reactions.
... The improvements in BD production due to US application have promoted research in this field to consolidate this energy as a viable alternative for BD production. There are various ultrasonic devices available in the market that can be used with this aim: ultrasonic baths [13,21], ultrasonic probes [22][23][24] and ultrasonic reactors [25,26]. Ultrasonic baths are devices designed for cleaning laboratory glassware or degassing solutions, which have several limitations when used for other purposes (namely, they do not allow direct sonication in the reaction medium, so the amount of energy per unit area that reaches the reaction system is limited). ...
Article
Ultrasound-assisted synthesis of biodiesel is a well known process that has been widely used in recent years. A reduction of the processing time and the amount of required catalyst as well as the possibility to work at room temperature have been achieved in most cases. Normally, the use of ultrasound replaces the conventional agitation and heating required to establish close contact between the two immiscible phases involved in this reaction (triglycerides and methanol). However, it may be not sufficient depending on the type of oil. In the present study, transesterification of oils with very different fatty acids composition has been conducted by combination of sonication and agitation cycles either at room temperature or at 50 °C. Application of ultrasound was carried out with an ultrasonic probe at 20 kHz frequency, 70% duty cycle and 50% amplitude. The experimental designs were planned by using the response surface methodology intended to find optimal values allowing a significant saving in the amount of catalyst and total reaction time required. Thus, oils with high content of unsaturated fatty acids (e.g. rapeseed and soybean oils) were found to reach biodiesel yields higher than the minimum value provided by the standard EN 14103 in shorter reaction times (below 15 min) compared to traditional transesterification. On the contrary, oils with high content of saturated fatty acids (e.g. coconut and palm oils) did not reach the required yield of 96.5% w/w. Finally, it may be concluded there is a positive influence of stirring and heating at reaction temperature between consecutive ultrasonic cycles on FAME yield and properties.
... Conversion and product selectivity in biomass systems tend to be poor due to insufficient catalystereactant contact. Immiscible alcoholelipidecatalyst systems are a fundamental problem in biodiesel synthesis [12]. ...
Article
Two important challenges need to be addressed to realize a practical biorefinery for the conversion of biomass to fuels and chemicals: (i) effective methods for the degradation and fractionation of lignocelluloses and (ii) efficient and robust chemical methods for the conversion of bio-feeds to target products via highly selective catalytic reactions. Ultrasonic energy promotes the pretreatment and conversion process through its special cavitational effects. In this review, recent progress and methods for combining and integrating sonication into biomass pretreatment and conversion for fuels and chemicals are critically assessed. Ultrasonic energy combined with proper solvents allows destruction of the recalcitrant lignocellulosic structure, fractionation of biomass components, and then assists many thermochemical and biochemical reactions, with increased equilibrium yields of sugars, bio-ethanol and gas products by 10–300%. Sonication promotes hydrolysis, esterification and transesterification in biodiesel synthesis and leads to reduced reaction time by 50–80%, lower reaction temperature, less amounts of solvent and catalyst than comparable unsonicated reaction systems. For algal biomass, sonication benefits the disruption, lysis and content release of macro and microalgae cells, and reduces the time required for subsequent extraction and chemical/biochemical reactions, with efficiencies typically being improved by 120–200%. High-frequency ultrasound of 1–3 MHz allows harvesting of microalgae, liquid product separation and in-situ process monitoring of biomass reactions, while high-intensity ultrasound at 20–50 kHz activates heterogeneous and enzymatic catalysis of the biomass reactions. The use of ultrasound in conversion of biomass to biofuels provides a positive process benefit.
... The influence of mass transfer on the production of biodiesel may be observed through mixing variation, as the use of different mixing methods (magnetic stirrers, ultrasound, dispersers, etc.) results in different conversions after the transesterification of rapeseed oil with methanol in both acidic and basic systems [9,10]. The production of B. Likozar and J. Levec / Fuel Processing Technology (2014) biodiesel from vegetable oils may thus be assisted by ultrasound, which is a useful tool for strengthening the mass transfer of immiscible liquids [11]. ...
Article
Full-text available
Detailed reaction kinetics of oil transesterification were studied based on mechanism and reaction scheme of individual triglyceride, diglyceride, monoglyceride, glycerol and fatty acid methyl ester containing different combinations of gadoleic, linoleic, linolenic, oleic, palmitic and stearic acids determined by high-performance liquid chromatography. Pre-exponential factors and activation energies were correlated with molecular structure in terms of chain lengths and double bonds by response surface models. The activation energies of forward reactions were 47-61 kJ mol(-1) with backward ones being 31-49 kJ mol(-1), depending on component structure. Mass transfer during initial emulsion phase was acknowledged by determining diffusivities, distribution coefficients, molar volumes, boiling points and viscosities of individual components. Model was validated for a wide range of temperatures, hydrodynamic conditions, dispersed and continuous phase ratios, and methanolysis catalyst concentrations. Rotational speed had the most profound influence on the duration of transport phenomena-limited region spanning the latter to 27 mm upon use of 100 rpm. Economics of the process were finally evaluated in terms of alcoholysis cost and price breakdown. Proposed methodology may be usefully applied to transesterification syntheses employing heterogeneous catalysis and enzymes, as well as various renewable resources such as microalgae lipids, waste oils, bioethanol and biobutanol.
... Variation of agitation intensity influences the mass transfer rate from continuous to dispersed phase and ultimately the yield [10,22,25,26]. The mixing variation by use of different mixing methods results in different conversions for alcoholysis reaction [26][27][28]. Thus, optimization of mechanical agitation and evaluation of overall kinetics (mass transfer and chemical) is essential in alcoholysis reaction for biodiesel production. ...
... The authors also compared power consumption, noting that the use of ultrasound achieved higher yields with less electrical power than any of the comparison methods. [104] Zhu et al.reported on the use of ultrasound in biodiesel production using base catalyzed reaction. The study included an investigation into the effect of frequency. ...
Article
This work aimed to improve the understanding of the use of microwaves and ultrasound for chemical processes. Using biodiesel production as the case for study, the non-linear effects of high intensity ultrasonics, electromagnetic loss, and microwave heating were explored. Cavitation and atomization phenomena were used to describe the process of ultrasonic emulsification. The dielectric loss mechanisms pertinent to the biodiesel production materials were described as the connection to between the effects of ultrasonic emulsification and microwave heating. Superheating and anisothermal heating phenomena were identified as the specific advantages afforded by microwave heating. High intensity ultrasonics was found to be capable of creating emulsions of biodiesel reactants with uniform dispersed phase droplets. Through optical microscopy, the ability to control the dispersed phase droplet size by altering the frequency and intensity of ultrasound was confirmed. This ultrasonic technique was investigated by measuring complex permittivity of the emulsions from 500 MHz and 5 GHz. The dielectric loss of emulsions consisting of methanol and soybean oil indicated that ultrasonic treatments could be used to alter the microwave absorption. Microwave heating tests of ultrasonically formed emulsions confirmed the permittivity results practically. The superheated boiling point of methanol and heating rate of methanol was extended to higher temperatures and rates in ultrasonically formed emulsions. Microwave heating of ultrasonically mixed emulsions was shown to result in faster transesterification relations than microwave heating of conventionally mixed emulsions. Finally, utilizing ultrasonics to optimize microwave absorption was shown capable of transesterification without catalyst.
... irradiation and reported optimum conditions for the formation of ethyl ester under ultrasonic irradiation at 25 C, which were E/T (ethanol to triolein) molar ratio of 6:1, base catalyst (NaOH or KOH) concentration of 1 wt.%, and reaction time of less than 20 min. Lifka and Ondruschka [108] studied the effect of ultrasonication versus mechanical stirring on the alkaline transesterification of rapeseed oil using NaOH at a concentration of 0.5% w/w at 45 C. A conversion of 80e85% was obtained for both ultrasonicated and mechanically stirred reactions after 30 min. Carmen et al. [[109]] used ultrasonically driven continuous process for palm oil transesterification and reported >90% conversion at 20 min residence time in reactor with 6:1 methanol to oil molar ratio.Table 8 shows the work carried out for bio-diesel production from various feedstocks under different conditions using ultrasound irradiation. ...
Article
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Editors and authors as the authors have plagiarized parts of a paper that had already appeared in Fuel, 89 (2010) 1–9, doi:10.1016/j.fuel.2009.08.014.One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.
... Hoang et al. [108] studied effects of molar ratio, catalyst concentration and temperature on transesterification of triolein with ethanol under ultrasonic irradiation and reported optimum conditions for the formation of ethyl ester under ultrasonic irradiation at 25°C were E/T (ethanol to triolein) molar ratio of 6:1, base catalyst (NaOH or KOH) concentration of 1 wt.%, and reaction time of less than 20 min. Lifka and Ondruschka [109] studied the effect of ultrasonication versus mechanical stirring on the alkaline transesterification of rapeseed oil using NaOH at a concentration of 0.5% w/w at 45°C. A conversion of 80-85% was obtained for both ultrasonicated and mechanically stirred reactions after 30 min. ...
Article
Among the options explored for alternative energy sources, bio-diesel is one of the most attractive. This paper discussed about the various production processes, few of which are applied at industrial level also, to produce basically FAME (later can be utilized as bio-diesel after purification) and will be termed as bio-diesel in this paper. Transesterification of vegetable oils/fats and extraction from algae are the leading process options for bio-diesel production on large scale. This paper reviews briefly the literature on transesterification reaction using homogeneous, heterogeneous and enzyme catalysts. Employing also ultrasound, microwave and supercritical alcohol techniques and also algae based bio-diesel.
... Pretreatment process using a stirrer rate of 400 rpm was utilized by Yuan et al. (2008) in the pretreatment of waste rapeseed oil with high FFA to produce biodiesel. Lifka and Ondruschka (2004) have studied the PTSA as an acid catalyst and different methods of mixing using a magnetic stirrer, ultrasound and ultraturrax. The study found that ultrasonic mixing was lowest in energy costs. ...
Article
In this study, biodiesel was produced from sludge palm oil (SPO) using tolune-4-sulfonic monohydrate acid (PTSA) as an acid catalyst in different dosages in the presence of methanol to convert free fatty acid (FFA) to fatty acid methyl ester (FAME), followed by a transesterification process using an alkaline catalyst. In the first step, acid catalyzed esterification reduced the high FFA content of SPO to less than 2% with the different dosages of PTSA. The optimum conditions for pretreatment process by esterification were 0.75% (w/w) dosage of PTSA to SPO, 10:1 M ratio, 60 °C temperature, 60 min reaction time and 400 rpm stirrer speed. The highest yield of biodiesel after transesterification and purification processes was 76.62% with 0.07% FFA and 96% ester content. The biodiesel produced was favorable as compared to EN 14214 and ASTM 6751 standard. This study shows a potential exploitation of SPO as a new feedstock for the production of biodiesel.
... The main aim of this study was to optimize the experimental conditions for maximum biodiesel production from base-catalyzed transesterification process using an ultrasonic irradiation technique. So far, several studies on the transesterification of various vegetable oils with different types of alcohols in the presence of a base-catalyst using ultrasound have been published [11,[16][17][18][19][20][21][22]. However, little research has been done to date on the applications of ultrasound irradiation in heterogeneous base catalyzed biodiesel production. ...
Article
Full-text available
In present study, production of fuel-quality biodiesel from high free fatty acid (FFA) feed stock, such as karanja oil, was investigated by ultrasonic assisted technique using dual step process. The initial acid value of oil was found to be 33 mg KOH/g corresponding to FFA level of 18 %, which was far above 1 % limit for satisfactory transesterification reaction using alkali catalyst. Hence, the dual-step process, H2SO4 catalyzed esterification followed by transesterification in the presence of heterogeneous base Ba(OH)2·8H2O catalyst was performed with ultrasonic technique at 30 kHz and amplitude 80 %. In the esterification step, effect of different operating parameters such as alcohol to oil molar ratio (6:1–12:1); catalyst loading, H2SO4 (0.5–1.5 %); reaction time (30–120 min); and temperature (30–60 °C) to reduce the FFA content was investigated. In the second step, heterogeneous Ba(OH)2·8H2O catalyzed transesterification of acid esterified oil was carried out by studying the effects of following variable on maximum conversion level: the concentrations of Ba(OH)2·8H2O catalyst, reaction time, temperature, and alcohol to oil molar ratio. The product conformation was done using 1H-NMR (proton nuclear magnetic resonance). The physicochemical properties were determined and compared with the biodiesel standards. In addition, thermo-oxidative stability and cold flow properties of karanja oil and its methyl ester were also investigated.
... Ultrasound improves the interfacial area between the immiscible reactants which accelerates the reaction and shortens the reaction time [1,2]. Application of ultrasound is also economically acceptable because the energy input is only one-third to a half of the energy that is consumed by mechanical agitation [3,4]. A limitation of the use of ultrasound is related to more difficult scale up and industrial application of sonochemical reactors [5]. ...
Article
The sunflower oil transesterification, catalyzed by KOH in the presence of ultrasound, was optimized by combining a 34 full factorial design of experiments with either a back-propagation artificial neural network (ANN) with the topology 4–10–1 or the response surface methodology (RSM). Four input factors, methanol/oil molar ratio, reaction temperature, catalyst loading and time and one output response, FAME yield, were included into the optimization study. The main goals were to test how accurately these two combinations predict and simulate the FAME yield achieved by the base-catalyzed methanolysis of sunflower oil under ultrasonication. Another aim was to compare the performances of the developed two models as a tool assisting decision making during the investigated methanolysis process. The ANN is shown to be a powerful tool for modeling and optimizing FAME production. Its predictions of FAME yield are very good all through the methanolysis process studied in wide ranges of the process factors. This is proved by a low value (±3.4%) of the mean MRPD between the experimental and simulated values of FAME yield, suggesting that they are almost the same. The ANN predictions were much better than those (±24.2%) obtained by the second-order polynomial equation from the RSM. The generalization ability of the developed ANN model for the base-catalyzed methanolysis optimization was well documented for different feedstocks and operational variables in the presence and absence of the ultrasound. The maximum FAME yield of 89.9% predicted by the ANN model could be achieved in 60 min at the reaction temperature of 30 �C, the initial methanol/oil molar ratio of 7.5:1 and the catalyst loading of 0.7%.
... Lifka and Ondruschka [37] reported that agitation is an important factor for biodiesel production. Therefore, in this study, the agitation speed was investigated to improve the FAME yield from dried biomass. ...
Article
Novel biodiesel or fatty acid methyl ester (FAME) was produced from dried biomass of Schizochytrium limacinum with dimethyl carbonate over a time period of 30 min. The highest FAME yield could reach 84% at 85 °C with a ratio of dried biomass to dimethyl carbonate of 1:4 w/w, with extra solvent of petroleum ether, 1.5 wt. % methanesulfonic acid (based on oil weight) and an agitation speed of 150 rpm. Biomass dried with 60-120 silica gels at 38 °C for 30 min was investigated. FAME was purified using Amberlyst™ 15 dry resin. FAME was analyzed via gas chromatography-mass spectrometry with the internal standard method. The properties of FAME met the international standard ASTM D 6751-02. The results revealed that all of the reaction variables in study had positive effects. Present study indicate that FAME could be a potential alternative to diesel.
... The ultrasound wave frequency seems to affect the reaction rate and the biodiesel yield. The use of ultrasound has an extra advantage as it requires one-third to a half of the energy that is consumed by mechanical agitation [112,[115][116]. Transesterification through ultrasonication can be carried out in a water bath (indirect sonication) or using a horn (direct sonication). ...
Chapter
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Limited reserves of fossil fuels as well as the growing concern for the environment, has led to a worldwide search for renewable energy sources, among which biodiesel, a mixture of fatty acid methyl esters (FAME), is one of the most perspective alternative fuels since it is a non-toxic and can be produced from different renewable sources through simple cost-effective alcoholysis, while being compatible with existing infrastructures. Vegetable oils, as renewable in nature and environmentally friendly, with a possibility to be produced on a large scale, represent a promising feedstock for biodiesel production. In this chapter, a comprehensive review of different vegetable oils as a feedstock for biodiesel synthesis is reported, including edible and non-edible oils, as well as waste vegetable oils. Selection of feedstock for biodiesel production mainly depends on the specific conditions and circumstances in some region (climate, presence of certain crops, the economic development of a country, etc.). Various fatty acid compositions of triacylglycerols directly determine the quality and fulfillment of the standards of biodiesel. One of the crucial points which determine technology route for biodiesel synthesis is content of free fatty acids (FFA) which might be present in vegetable oils, as well as the presence of water and other compounds. Also, many analysis performed in the past have shown that the production cost of biodiesel is mainly determined by the price of used feedstock, which represents 70-80% of total production costs of biodiesel. Currently more than 95% of feedstock comes from edible oils since they are easily accessible, consists mainly of triacylglycerols, whereby the properties of biodiesel produced from these oils are suitable to be used as diesel fuel substitute. Most commonly used edible oils for biodiesel production are rapeseed, soybean, sunflower and palm. However, for economic and social reasons, in recent years research and development of biodiesel production has focused on other sources of triacylglycerols, in order to replace edible oils by lower-cost non-edible plant oils and the waste cooking oils, feedstocks that are unsuitable for human consumption. Properties of different oils and biodiesel obtained from them as well as the technologies suitable for biodiesel synthesis are compared in this chapter. The wellknown fact is that the conventional and to-day widely applied homogeneous method of biodiesel synthesis is sensitive to the presence of impurities in the oil, primarily the presence of FFA and water. Furthermore, biodiesel synthesis is followed by creation of large amount of wastewater produced during neutralization of catalyst and purification of final product. The drawbacks of a homogeneous process can be avoided by applying technologies based on utilization of heterogeneous catalyst or by application of the noncatalytic supercritical process of biodiesel synthesis. These technologies for biodiesel production were also analyzed and compared.
... There are several ways to overcome the mass transfer limitation and enhance the contact between two phases such as the use of large excess alcohol, mechanical mixing, using polar aprotic solvents or inert cosolvent, ultrasonic and hydrodynamic cavitation, and supercritical conditions. However, these techniques are associated with one or more drawbacks like the high cost of solvent or require a very excessive amount of solvents, the high cost of operations, generation of huge amounts of effluents, and higher capital costs [22,41]. It was evident that eliminating the mass transfer limitations using cosolvent (which forms pseudo-homogeneous phase) or catalyst-free processes (conducted at high temperature and pressure), faster transesterification rates could be achieved [18][19][20]. ...
Chapter
In this chapter, the technical difficulties of conventional base-catalyzed transesterification and conventional esterification process using concentrated sulfuric acid in a homogeneous form have been discussed in detail. The use of low-quality feedstocks like waste vegetable oils and non-edible oils for biodiesel production has been explored. To address the mass transfer limitations in the conventional transesterification process, the addition of a phase transfer catalyst such as tetramethylammonium bromide (TMAB) has been investigated. Thereafter, the esterification of Karanja oil with high free fatty acid content through a non-catalytic method has been discussed. Kinetic modeling of the non-catalytic esterification along with process simulation in Aspen Plus was performed. Finally, the potential application of corncob-derived solid acid catalyst (SAC) for the esterification of oleic acid to produce biodiesel has been discussed.
... The phenomenon in this case contradicts earlier studies on similar subject [35]. However, the phenomenon agrees with others previous studies on related works [36]. Figure 4 shows the influence of the amount of catalyst on the yield of biodiesel. ...
Article
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This study is aimed at producing biodiesel from Allanblackia parviflora seed oil as a new non-edible alternative resource. The amount of oil extracted from the seeds was approximately 49% and was mainly composed of linoleic acids (66.68). The Allanblackia parviflora methyl esters (APME) were prepared using NaOH as a homogeneous base-catalyst for the transesterification. The rate of conversion of the triglycerides to methyl esters was determined using Gas Chromatograph with an optimum yield of 97.1%. The conditions under which this maximum yield (97.1%) was obtained include methanol to Allanblackia parviflora oil ratio of 6:1, reaction temperature of 60 ℃, NaOH concentration of 1% and reaction time of 2 h. The properties of the methyl esters were comparable to fuel properties of conventional diesel using ASTM and European Union standards. The seeds of Allanblackia parviflora can be described as promising non-edible resource.
... Pabrik kelapa sawit (PKS) di Bengkulu sebagian besar mengolah tandan buah segar (TBS) menjadi crude palm oil (CPO). CPO apabila dimanfaatkan sebagai bahan bakar masih dijumpai masalah, yaitu viskositas yang terlalu tinggi jika dibandingkan dengan petroleum diesel (Jan dan Bemd, 2004). Oleh karena itu penggunaan CPO sebagai bahan bakar masih harus dikonversi menjadi metil ester (Hanh et al., 2007;Stavarache et al., 2007). ...
... These effects can strongly improve enzymatic reactions [20,21] or contribute to enzyme deactivation [22]. Besides, ultrasound uses only one-third to a half of the energy that is consumed by mechanical agitation [23][24][25]. Some advantages of the ultrasound in enzymecatalyzed reactions may be summarized as: minimization of the reaction time, reduction of the reagent amounts, yield increasing, and the chemo-, region and stereoselectivities of reactions that normally would not occur in normal conditions. ...
Article
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The main objective of this work was to investigate the enzymatic production of ethyl esters in continuous mode coupled to an ultrasound bath. For esterification reactions soybean free fatty acids (FFA) and ethanol were used as substrates, and Novozym 435 and Lipozyme TL IM, as catalysts. The experimental system consisted of a packed bed glass reactor immersed in an ultrasound bath and the following variables were studied: ethanol to FFA molar ratio of 1:1, 1:3 and 1:6, substrates flow rate of 2.5 and 5 mL/min, at 65 °C and 132 W ultrasound power output. It was noticed that the excess alcohol favored the esterification reaction with the best conversions observed, 95%, at 6 min reaction for 1:6 FFA to ethanol molar ratio, 2.5 mL/min feeding flow rate. Increasing the substrates feeding flow rate decreased the conversion down to 87% and replacing the Novozym 435 by Lipozyme TL IM no satisfactory conversions were achieved. This type of reactor demonstrated good performance for ethyl esters production, opening promising perspectives for use in the production of other types of esters such as those aromatic and others with high value.
... Ultrasonic reactors could be an effective system for improving the performance of the transesterification process with shorter reaction times. The energy requirement for biodiesel production complies very well with the overall energy output ( Lifka and Ondruschka, 2004;Wang et al., 2007;Chand et al., 2010). The conventional mechanical agitation or stirring improves the interfacial surface area and mass transfer characteristics of the process. ...
... The ultrasound wave frequency seems to affect the reaction rate and the biodiesel yield. The use of ultrasound has an extra advantage as it requires one-third to a half of the energy that is consumed by mechanical agitation [112,[115][116]. Transesterification through ultrasonication can be carried out in a water bath (indirect sonication) or using a horn (direct sonication). ...
Chapter
In recent years the production of vegetable oils (sunflower, linseed, rapeseed, soybean, olive, etc.) has significantly increased, oils being considered a major economic resource, mainly used in the food industry or as raw materials for the biodiesel production, as well as for the oleochemical and pharmaceutical industries. Authentication of vegetable oils refers mainly to two aspects. On one hand, it is related to establishing conformity according to label - in terms of plant species, part of the plant (e.g., discrimination between palm oil and palm kernel oil), geographical origin, crop year, processing technique (differentiation of minimum processed oils such as cold pressed oils from refined oils). On the other hand, detection of adulteration of expensive vegetable oils and fats such as olive oil or cocoa butter with cheaper oils is another important issue concerning oils authentication. In the last decade, researchers in the food quality control field, showed an increased interest to establish methods for products authentication. This trend results from the consumers enhanced demand for quality products. Vegetable oils authentication by means of establishing the geographical origin of oil seeds goes with the new trend of protecting the local food products. Protected designation of origin (PDO), protected geographical indication (PGI) and Traditional Specialty Guaranteed (TSG) are geographical indications defined in European Union Law to protect regional foods and to eliminate the dishonest practices. Those laws are inflicted in the European Community since 1992 and gradually extended to the non-UE countries by various joint agreements. The fatty acid composition of vegetable oils is the main factor influencing their nutritional value and properties. In recent years, new and efficient methods for the determination of the fatty acids profile of different kind of samples (e.g., vegetable oils, lipid extracts from different vegetable or animal tissues) have evolved, being partially fed by the general trend in the chemical literature concerning the food authenticity assessment. Among the most envisaged physical methods of analysis, vibrational spectroscopy (NIR, FT-IR and Raman), nuclear magnetic resonance (1H-, 13C-NMR) and chromatographic techniques (GC, HPLC) can provide structural and compositional information useful for vegetable oils authentication. Special attention has been focused on 1H-NMR spectroscopy which leads to a global fatty acids profile (in terms of linolenic, linoleic, mono-unsaturated and saturated fatty acids) in a non-invasive manner and mild analysis conditions which do not require chemical transformations prior to/during analysis, as compared to chromatographic techniques. Moreover, spectra (both NMR or vibrational) can be considered as fingerprints of samples taken into analysis, thus being helpful for authentication purposes. Authentication of a food product is almost impossible without the use of statistical methods applied to data bases obtained from genuine samples. Among these methods, multivariate statistical analysis - Principal Component Analysis (PCA), Discriminant Analysis (DA) - have proven suitable for vegetable oils authentication. In this chapter, we aim to investigate the potential of physical methods (NMR or vibrational spectroscopies and chromatography) coupled with statistical data processing to assess vegetable oils authentication issues such as establishing conformity according to label and detection of adulteration.
... Among experimental conditions, temperature and agitation speed were chosen for further optimization since a high correlation between the two variables and the methanol release rate was expected. Initial ranges of temperature and agitation speed considered for optimization was set to 30-50 • C and 100-300 rpm based on optimal temperatures and agitation speed (45 • C and 600 rpm for Novozym 435 and Lipozyme RM IM, respectively [21]) and optimization results previously reported by other researchers [15,21,22]. Sonare and Rathod [21] reported that the effect of temperature and agitation speed on the transesterification reaction using two enzymes (Novozym 435 and Lipozyme RM IM). ...
Article
A silica gel-based substrate feeding system was developed to prevent methanol inhibiting the catalyst during enzymatic biodiesel synthesis. In the system, silica gel swelled upon methanol addition and subsequently released it in a controlled manner to prevent excess methanol affecting the enzyme. Biodiesel was synthesized by the enzymatic transesterification of canola oil with methanol. For this reaction, enzyme loading, methanol/oil molar ratio, silica gel dosage, glycerol content, and methanol feeding method were tested using commercial immobilized enzymes (Novozym 435 and Lipozyme RM IM from Novozymes). The results showed that conversion was highest with controlled substrate feeding rather than direct methanol addition, suggesting that the method developed here can easily prevent enzyme inhibition by limiting methanol concentration to an acceptable level.
... [19] Effect of agitation speed on DMC-Sm-BioDs yield In biodiesel production, agitation speed is an important factor, as demonstrated by Lifka and Ondruschka. [28] In DMC-Sm-BioDs production, the effect of the speed of agitation in the 50À200 rpm range was investigated by keeping all other conditions constant, as previously mentioned under section, affect of reaction temperature on DMC-Sm-BioDs yield. The biodiesel yield increased with increased agitation speed from 50 to 150 rpm and subsequently remained constant (see Figure 6). ...
Article
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The kinetics and transesterification of Sapindus mukorossi seed kernel powder with dimethyl carbonate (DMC) were explored using a mixed KOH–Folch solution as a catalyst for the preparation of biodiesel. The effect of the reaction conditions (the molar ratio of S. mukorossi seed kernel powder with DMC, the catalyst amount and the reaction time, the reaction temperature and the agitation speed) on DMC-Sm-BioDs yields were investigated. The highest DMC-Sm-BioDs yield was 95% at 60 °C for 60 min with a molar ratio of S. mukorossi seed kernel powder to DMC 1:3 and 1.5% KOH (based on DMC weight). DMC-Sm-BioDs was analyzed by gas chromatography-mass spectrometry (GC-MS) to identify the fatty acid dimethyl esters. The activation energy (Ea) was 75.2 kJ mol−1, and the pre-exponential factor was 1.09×108 min−1. The DMC-Sm-BioDs produced from S. mukorossi seed kernel powder is characterized for various properties, such as the kinematic viscosity at 40 °C, the specific gravity at 25 °C, the flash point, the pour point, the cloud point, the acid value and the copper stripe corrosion. DMC-Sm-BioDs satisfied the European quality standards defined in ASTM D6751-02.
Article
In this research, Daturametel Linn seed oil was investigated for the first time as a promising non-conventional feedstock for preparation of biodiesel fuel. The maximum extraction of oil was observed to be 38.57 (wt) % and the activation energy Ea (25.8 kJ mol−1) was calculated. Further the thermodynamic properties for oil extraction were determined as activation enthalpy = 25.051 kJ mol−1, activation entropy = −241.25 J mol−1, and the Gibb's energy = 105.39 kJ mol−1. This present study also reports the new single-step ultrasound production of biodiesel from high fatty acid D.metel Linn oil using sulfuryl chloride as catalysts in which 95.50% yield was achieved with 2 h. Different reaction parameters for oil extraction and biodiesel production were optimized. This analysis confirms that Daturametel Linn biodiesel is appropriate alternative to petroleum diesel with recommended fuel properties as per specified standards.
Article
In the present work, the transesterification of cottonseed oil with methanol and ethanol, in the presence of alkali catalyst (NaOH), using low-frequency ultrasonication (24 KHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Both conventional and in situ transesterification were investigated. Use of ultrasonication in conventional transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Higher concentrations of NaOH (2.0%) gave higher ester yields. Use of ultrasonication in conventional transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ transesterification, the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol, use of ultrasonication led to high ester yields (98%) in only 40 min of reaction time while use of mechanical stirring gave low yields (78%) even after 4 h of reaction time. In situ transesterification gave similar ester yields to those obtained by conventional transesterification being an efficient and economical process. Reaction rate constants were calculated, using first-order reaction kinetics, to be equal to 3.1 × 10−3 s−1 for conventional transesterification using methanol and 2.0% NaOH, and 7.0 × 10−4 s−1 using ethanol.
Chapter
Biodiesel is an energy source that is mostly derived from plant‐based oils through a transesterification and esterification reactions with alcohols. Due to the immiscibility of the reactants, the reaction is only limited to the interface and vigorous mechanical stirring is often needed to homogenize the reactants. To achieve high yields (>90%) in about 2 h, temperatures between 50°C and 65°C in the presence of 0.5 to 3.0 wt. % of catalyst are usually required. The use of ultrasonic energy as the source of mixing has become a great interest as it can increase the interface area leading to higher biodiesel yield. During ultrasonication, the cavitation bubbles will be formed and subsequently collapse asymmetrically once the critical sizes are reached. The boundary of the reacting phases will be disrupted by the micro jets that result from these collapses. It will also result in a temperature rise at the locality of the phase boundary. The use of ultrasonic energy in conjunction with a heterogeneous catalyst can lead to shorter reaction times of 10–40 min with two to three times lower amount of catalyst needed as compared to those expected in normal mechanically stirred reactor. Thus, the process will require shorter reaction time, lower catalyst amount and lower energy input to result in high methyl ester yield.
Article
In the present work, the transesterification reaction of rapeseed oil with methanol, in the presence of alkaline catalysts, either homogeneous (NaOH) or heterogeneous (Mg MCM-41, Mg–Al Hydrotalcite, and K+ impregnated zirconia), using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Selection of heterogeneous catalysts was based on a combination of their porosity and surface basicity. Their characterization was carried out using X-ray diffraction (XRD), Nitrogen adsorption–desorption porosimetry and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The activities of the catalysts were related to their basic strength. Mg–Al hydrotalcite showed particularly the highest activity with conversion reaching 97%). The activity of ZrO2 in the transesterification reaction increased as the catalyst was doped with more potassium cations, becoming thus more basic. Use of ultrasonication significantly accelerated the transesterification reaction compared to the use of mechanical stirring (5 h vs. 24 h).Given the differences in experimental design, it can be concluded that the homogeneous catalyst accelerated significantly the transesterification reaction, as compared to all heterogeneous catalysts, using both mechanical stirring (15 min vs. 24 h) and ultrasonication (10 min vs. 5 h). However, the use of homogeneous base catalysts requires neutralization and separation from the reaction mixture leading to a series of environmental problems related to the use of high amounts of solvents and energy. Heterogeneous solid base catalysts can be easily separated from the reaction mixture by simple filtration, they are easily regenerated and bear a less corrosive nature, leading to safer, cheaper and more environment-friendly operations.
Article
In the present work, the transesterification reaction of soybean frying oil with methanol, in the presence of different heterogeneous catalysts (Mg MCM-41, Mg-Al Hydrotalcite, and K+ impregnated zirconia), using low frequency ultrasonication (24 KHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Selection of catalysts was based on a combination of porosity and surface basicity. Their characterization was carried out using X-ray diffraction, Nitrogen adsorption-desorption porosimetry and scanning electron microscopy (SEM) with energy dispersive spectra (EDS). The activities of the catalysts were related to their basic strength. Mg-Al hydrotalcite showed particularly the highest activity (conversion 97%). It is important to mention that the catalyst activity of ZrO2 in the transesterification reaction increased as the catalyst was enriched with more potassium cations becoming more basic. Use of ultrasonication significantly accelerated the transesterification reaction compared to the use of mechanical stirring (5 h versus 24 h).
Article
Biodiesel production is a rapidly advancing field worldwide, with biodiesel fuel increasingly being used in compression ignition (diesel) engines. Biodiesel has been extensively studied and utilised in developed countries, and it is increasingly being introduced in developing countries, especially in regions with high potential for sustainable biodiesel production. Initial sections systematically review feedstock resources and vegetable oil formulations, including the economics of vegetable oil conversion to diesel fuel, with additional coverage of emerging energy crops for biodiesel production. Further sections review the transesterification process, including chemical (catalysis) and biochemical (biocatalysis) processes, with extended coverage of industrial process technology and control methods, and standards for biodiesel fuel quality assurance. Final chapters cover the sustainability, performance and environmental issues of biodiesel production, as well as routes to improve glycerol by-product usage and the development of next-generation products. Biodiesel science and technology: From soil to oil provides a comprehensive reference to fuel engineers, researchers and academics on the technological developments involved in improving biodiesel quality and production capacity that are crucial to the future of the industry.
Article
Heterogeneously catalyzed transesterification process has by far been one of the most popular methods of biodiesel production particularly for the oil feedstock containing large amount of free fatty acid. However, the major constraint of the method is the poor yield of biodiesel and a long reaction time that increased its production cost. With an objective to increase the product yield in lesser time, the current work investigated the effect of addition of ultrasound and addition of cosolvent in the heterogeneously catalyzed transesterification reaction. Three commonly used solid catalyst – calcium oxide (CaO), calcined sodium silicate (CSS) and sulfated zirconia (SZ) were chosen for study. The results suggested that there was a remarkable increase in the yield of biodiesel in comparison to the conventional mechanically stirred process. CSS showed the best catalytic activity both in first use and in repeated uses. It gave a maximum yield of 97% biodiesel in 120 minutes with 9:1 molar ratio of alcohol to oil 3 wt.% of catalyst and 10 wt.% of catalyst. For CaO and CSS a noticeable difference in biodiesel yield was observed upon addition of cosolvent. CaO gave 76% yield with cosolvent and 65% without it. SZ gave 73% biodiesel with cosolvent and 61% without. Since petrodiesel was used as the cosolvent it was not required to remove the cosolvent from biodiesel during the purification process.
Article
The transesterification of two different frying oils (soybean oil and a mixture of soybean and cotton seed oil) with methanol, in the presence of an alkali catalyst (NaOH), by means of low-frequency ultrasonication (24 kHz, 200 W) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. The two different frying oils gave similar yields of isolated methyl esters both under mechanical stirring and ultrasonication. Also the physical and chemical properties of the two biodiesel fuels produced were investigated. The fuels produced were characterized by determining their density, viscosity, flash point, boiling point, cetane number, sulfur content, cloud point, pour point, cold filter plugging point, acid value, iodine value, and saponification value. From the physical and chemical properties of the two biodiesel fuels, it is concluded that these fuels have very similar properties to those of conventional diesel, except for the cetane number, which is higher, and the sulfur content of the biodiesel, which is negligible. Thus, experimental biodiesel fuels are environmentally friendly and attractive alternatives to conventional diesel.
Article
Biodiesel has become one of the premier forms of alternative energy sources. However, its growth is hindered by the cost of production, which makes it uncompetitive compared to petrodiesel. Hence, research efforts are ongoing to reduce the cost of production of biodiesel using various emerging approaches. Ultrasound has been reported to aid biodiesel formation at relatively lower energy costs. However, not many reports are available that give in-depth analysis of the effects of ultrasound on biodiesel formation. This paper reports the result of a study to evaluate the effect of high-frequency ultrasound on the synthesis of biodiesel from soybean oil using methanol and potassium hydroxide as catalysts. The effects of various parameters, such as ultrasonic power, ultrasonic frequency, oil/methanol molar ratio, catalyst loading, and temperature, on biodiesel formation were studied to optimize the process. It is shown that high-frequency ultrasound can achieve >90% conversions within 30 min with relatively low-energy inputs. A specially designed multifrequency ultrasonic reactor, which has the potential to reduce the energy losses because of scattering, reflection, and absorption, was used for this study.
Article
Alkaline transesterification of Silybum marianum seed oil to biodiesel using methanol and ethanol was studied. The two methods used were conventional stirring (600 rpm) and ultrasonication (40 kHz). Oil was extracted from the seeds, followed by physico-chemical properties' determination and transesterification to biodiesel. The seeds contained 46% oil which had low free fatty acids (FFA) (0.68%). Linoleic acid (65.68%) was the main composition of the oil. Ultrasonication transesterification with methanol gave the highest yield (95.75%) after 20 min. Yields of methyl esters were higher than respective yields of ethyl esters. Using first order reaction kinetics model, the reaction rate constants were 2.3 X 10(-2) s(-1) and 7.0 X 10(-3) s(-1) for ultrasonication using methanol and ethanol, respectively. With the exception of oxidative stability (2.1 h) and iodine values (132-methyl and 133-ethyl esters), properties out of range but can easily be improved, the remaining properties including cetane number, flash point and the cold flow ones of both methyl and ethyl esters were similar and comparable to Chinese, ASTM and European Union standards. The findings of this study complement with the abundance of S. marianum oil at cultivation and silymarin industrial production as by-product indicates its potentially new non-edible feedstock for biodiesel.
Article
Introduction The utilization of biodiesel as an alternative fuel is turning out to be progressively famous these days because of worldwide energy deficiency. The enthusiasm for utilizing Jatropha as a non-edible oil feedstock is quickly developing. The performance of the base catalyzed methanolysis reaction could be improved by a continuous process through a microreactor in view of the high mass transfer coefficient of this technique. Materials & Methods Nanozirconium tungstovanadate, which was synthetized using sol-gel preparation method, was utilized in a complementary step for biodiesel production process. The prepared material has an average diameter of 0.066 &µm. Results First, the NaOH catalyzed methanolysis of Jatropha oil was investigated in a continuous microreactor, and the efficient mixing over different mixers and its impact on the biodiesel yield were studied under varied conditions. Second, the effect of adding the nanocatalyst as a second stage was investigated. Conclusion The maximum percentage of produced methyl esters from Jatropha oil was 98.1% using a methanol/Jatropha oil molar ratio of 11 within 94 s using 1% NaOH at 60 &°C. The same maximum conversion ratio was recorded with the nanocatalyst via only 0.3% NaOH.
Article
This study evaluated the most suitable pulse mode (pulse ON–OFF pattern) for transesterification of waste cooking oil (WCO) using sodium hydroxide. Pulse sonication effect was investigated using ethanol, methanol, and ethanol–methanol mixtures to convert waste cooking oil into biodiesel. The importance of duty cycle (pulse-mode operation) and the role of reaction temperature during the conversion process were discussed. A maximum biodiesel yield of 99% was obtained for a pulse ON–OFF combination of 7 s–2 s at 150 W power output, and the optimum reaction conditions of 9:1 alcohol-to-oil molar ratio (50%-ethanol, 50%-methanol), 1 wt.% of NaOH, and 1.5 min reaction time.
Data
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Lipase was produced by Penicillium camembertii KCCM 11268 under solid state fermentation (SSF), and the production process was optimized by using statistical experimental designs. The initial moisture content, cultivation time, inoculum size and concentration of basal medium were considered as the factors of optimum conditions for SSF. P. camembertii KCCM 11268 was cultivated in SSF using wheat bran as the substrate for lipase production. Under the optimized condition, lipase activity was reached around 7.8 U/ml after eight days fermentation. To partially purify the lipase, ammonium sulfate (80% saturation) was added to the crude lipase solution and concentrated using a diafil-tration (VIVAFLOW 50). The concentrated lipase solution from P. camembertii KCCM 11268 (PCL) was immobi-lized on silica gel by cross-linking method. Also, PCL was mixed with a commercial lipase solution from Candida rugosa (CRL), and this mixture was co-immobilized on silica gel. The immobilized and co-immobilized lipase activities were 1150.1 and 7924.8 U/g matrix, respectively. Palm oil and methanol were used as substrates and 1 mmol of methanol was added every 1.5 h and 2 times during biodiesel production. The reaction was carried out at temperatures of 30, 40, 50, 60 and 70 o C. The maximum biodiesel conversion by co-immobilized lipase was 99% after 5 h at 50 o C.
Article
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Transesterification of triglycerides with ethyl acetate instead of methanol seems to be advantageous in respect to glycerin waste elimination. Sodium methanolate and metal sodium dispersion (0.4%) were used as a catalyst. The reaction occurred very quickly (5–30 min) at the temperature of 22–78 °C in a similar way as the common methanolysis but reached an equilibrium with a high content of acetylated monoglycerides (9–13%) and diglycerides (3–6%) in addition to fatty acid ethyl esters (72–81%) and glycerol acetates (4.5–6.2%). A similar product yield could be obtained while using 5% p-toluenesulfonic acid as a catalyst but after 40 h of reaction time.During reactive distillation (RD) it was possible to evaporate the light volatile glycerol acetates and fatty acid ethyl esters and to shift the equilibrium towards the desired products. Reactive distillation was performed at the temperature of 200–230 °C by bubbling ethyl acetate vapor through rapeseed oil layer. Dodecylbenzene sulfonic acid (1%) was used as a catalyst. The product yield attained 8 g/h and was composed mainly of fatty acid ethyl esters (90%) and only little amounts of glycerol acetates. During the reaction a rapid decrease in catalyst activity was observed. The use of alkaline catalyst, like sodium methanolate, gave lower product yield of 2.6 g/h with higher content of glycerol acetates (7.7%) besides ethyl esters (90%). Using 2% zinc oxide as a catalyst contributed to obtaining only negligible yield of transesterification products (0.2 g/h).
Article
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The ultrasound-assisted sunflower oil methanolysis catalyzed by KOH was studied to define a simple empirical kinetic model useful for reactor design without complex computation. It was assumed that the neutralization of free fatty acids and the saponification reaction were negligible. The methanolysis process rate was observed to be controlled by the mass transfer limitation in the initial heterogeneous regime and by the chemical reaction in the later pseudo-homogeneous regime. The model involving the irreversible second-order kinetics was established and used for simulation of the triacylglycerol conversion and the fatty acid methyl esters formation in the latter regime. A good agreement between the proposed model and the experimental data in the chemically controlled regime was found.
Conference Paper
Transesterification is commonly used to produce biodiesel from methylester. In order to control the conversion process is useful to employ process monitoring, in particular monitoring of the mass transfer processes that limits the initial rates of transesterification. Monitoring of these initial stages of the reaction may allow for process optimization. Many methods have been identified to monitor reaction progress. This paper proposes a method to monitor the initial stages of the biodiesel production process using impedance measurement. The impedance measurements presented show the expected sigmoid curves that are associated with mass transfer (mixing) processes taking place during the early stages of the transesterification process.
Article
Adsorption behavior of methyl palmitate (MP), as a model substance of biodiesel fuel, onto silica surface in the presence of methanol and toluene was investigated, assuming the dry washing purification of biodiesel production process. Methanol and toluene affected amount absorbed of MP, especially methanol greatly affected amount absorbed of MP. The adsorption model was proposed based on the Langmuir type adsorption and two assumptions for competitive adsorption. The equilibrium adsorption constant, K, and the maximum number of the adsorption sites, XS, were determined by fitting the data to the proposed model. The proposed model agreed well experimental data. The magnitude of K correlated with the dielectric constant of each substance. The occupied surface area of silanol group estimated from XS was mostly the same as the reported values. These adsorption parameters were verified experimentally with other conditions.
Article
Biodiesel is gaining acceptance in the market as fuel and lubricant. It is expected that biodiesel industries will rapidly grow worldwide in the coming years and information on biodiesel feedstock, production, and characteristics will be crucial than ever especially for those using vegetable oils as feedstock as these are currently the major sources for making biodiesel. In the present paper, a comprehensive review is reported on feedstock, production technologies, and characteristics of biodiesel. More specifically, selected available vegetable oils are explored as feedstock for biodiesel production. Production technologies including latest catalyst developments are discussed. Finally, biodiesel characteristics and parameters influencing the corresponding properties are revealed. Since this paper covers a wide range in biodiesel area, it serves as a general public education medium as well as a research reference for biodiesel production from vegetable oils.
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The transesterification of Pongamia pinnata seed oil with dimethyl carbonate (DMC) for preparing DMC-BioD has been studied at the catalysis of potassium hydroxide (KOH). The effects of reaction conditions (ratio of P. pinnata seed oil and DMC, catalyst amount and reaction time, reaction temperature and agitation speed) on DMC-BioD yield were investigated. The highest DMC-BioD yield could reach 96% at refluxing temperature for 6 h with ratio of P. pinnata oil to DMC 1:3 w/w and 4% KOH (based on oil weight). Percentage of conversion has been analyzed by Gas Chromatography. P. pinnata seed oil DMC-BioD produced is characterized for the properties such as the kinematic viscosity at 40 °C, density at 25 °C, flash point (FP), pour point (PP), cloud point (CP), acid value and copper strip corrosion. P. pinnata seed oil DMC-BioD produced met with the quality standards defined under ASTM D675-02.
Article
Ultrasonic irradiation of a mixture of benzyl bromide, potassium cyanide, and alumina in an aromatic solvent yields benzyl cyanide, whereas mechanical agitation gives the Friedel–Crafts type product; sonication changes the main reaction pathway from aromatic electrophilic to aliphatic nucleophilic substitution.
Article
The measurement of a sonochemical effect (SE) requires the definition of the reference conditions for the so-called “silent reaction”. It is shown that it is impossible to define SE correctly in the case of heterogeneous reactions, due to the dramatic effect of the agitation on reaction rates. This is true not only from the quantitative point of view (effect of ultrasound on reaction rates) but also from the qualitative perspective (change of reaction pathway when ultrasound is applied). The first, and most dramatic, example of chemical switching described in the literature, and claimed to be due to ultrasound, is proven also to be observable under efficient agitation conditions.
Article
Biodiesel as alkyl esters derived from vegetable oils has considerable advantages in terms of environmental protection. In the present work, methyl esters were produced from sunflower oil by lipase-catalyzed reactions. The effect of organic solvent on alcoholysis rate was investigated and highest conversion (80%) was found in n-hexane and petroleum ether. Among several microbial lipases tested for alcoholysis activity in a solvent-free system, the best conversion (>90%) was found with lipase from Pseudomonas fluorescens (Amano AK) at the highest molar equivalent of oil:methanol (1:4.5). To reduce inactivation of commercial immobilized lipases by methanol, a three-step protocol consisting of the stepwise addition of 1 M equivalent of methanol at 5 h intervals, was developed. Also with immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) high conversion (>80%) was possible. Moreover, the transesterification could be conducted for at least 120 h during five batch runs without significant loss of activity.
Article
Waste bleaching earths from crude vegetable oil refining process contain approximately 40% of its weight as oil. Low valued oils are potential substrates for biodiesel fuel production. Vegetable oils from waste bleaching earth samples were organic-solvent extracted and identified as soybean, palm and rapeseed oil. Methanolysis was efficiently catalyzed by Rhizopus oryzae lipase in the presence of high water content, and by a single addition of methanol. R. oryzae lipase was not inactivated by methanol in concentrations lower than 4 milli-equivalents and 75% water content. Optimum conditions for methanolysis of extracted oils were 75% water content (by weight of substrate), an oil/methanol molar ratio of 1:4, and 67 IU/g of substrate with shaking of 175 rpm for 96 h at 35 °C. The highest conversion yield reached 55% (w/w) with palm oil after 96 h of reaction. Adverse viscosity conditions might have influenced methanolysis of extracted soybean and rapeseed oil in spite of high water or methanol concentrations.
Article
Vegetable oil fuels have not been acceptable because they were more expensive than petroleum fuels. With recent increases in petroleum prices and uncertainties concerning petroleum availability, there is renewed interest in vegetable oil fuels for Diesel engines. Dilution of oils with solvents and microemulsions of vegetable oils lowers the viscosity, but some engine performance problems still exist. The purpose of the transesterification process is to lower the viscosity of the oil. Pyrolysis produces more biogasoline than biodiesel fuel. Soap pyrolysis products of vegetable oils can be used as alternative Diesel engine fuel. Methyl and ethyl esters of vegetable oils have several outstanding advantages among other new renewable and clean engine fuel alternatives. The main factors affecting transesterification are the molar ratio of glycerides to alcohol, catalyst, reaction temperature and pressure, reaction time and the contents of free fatty acids and water in oils. The commonly accepted molar ratios of alcohol to glycerides are 6:1–30:1.
Article
Four different continuous process flowsheets for biodiesel production from virgin vegetable oil or waste cooking oil under alkaline or acidic conditions on a commercial scale were developed. Detailed operating conditions and equipment designs for each process were obtained. A technological assessment of these four processes was carried out to evaluate their technical benefits and limitations. Analysis showed that the alkali-catalyzed process using virgin vegetable oil as the raw material required the fewest and smallest process equipment units but at a higher raw material cost than the other processes. The use of waste cooking oil to produce biodiesel reduced the raw material cost. The acid-catalyzed process using waste cooking oil proved to be technically feasible with less complexity than the alkali-catalyzed process using waste cooking oil, thereby making it a competitive alternative to commercial biodiesel production by the alkali-catalyzed process.
  • Stavarche