Olivera Stamenkovic - Academia.edu (original) (raw)

Papers by Olivera Stamenkovic

Chemical Industry

Triethanolamine was applied as an efficient "green" cosolvent for biodiesel production by CaOcata... more Triethanolamine was applied as an efficient "green" cosolvent for biodiesel production by CaOcatalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4 °C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75 °C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.

Fuel

Crude biodiesel was proven as a cosolvent in the methanolysis of sunflower oil catalyzed by calci... more Crude biodiesel was proven as a cosolvent in the methanolysis of sunflower oil catalyzed by calcined CaO. This reaction was modeled and optimized statistically in terms of reaction temperature (33.2–66.8 °C), methanol-to-oil molar ratio (3.5:1–8.5:1) and catalyst concentration (0.219–1.065 mol/L). The cosolvent loading was 10 wt% (based on oil weight). The optimum reaction conditions were found to be: the methanol-to-oil molar ratio of 7.1:1, the catalyst concentration of 0.74 mol/L and the reaction temperature 52 °C, ensuring the best esters content of 99.8%, for the reaction time of 1.5 h, which is close to the reported experimental value of 98.9%. Also, the used catalyst was recycled with no additional treatment in the further four consecutive cycles under the following reaction conditions: methanol-to-oil molar ratio 6:1, the concentration of catalyst 0.642 mol/L (only in the first run), the reaction temperature 50 °C, cosolvent-crude biodiesel loading 10 wt% to oil weight. The second recycling reaction provided the highest FAME content of 97.7% after 5 h.

Journal of the Serbian Chemical Society

Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-he... more Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 ?C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol?L-1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7?1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two prov...

Reciklaza i odrzivi razvoj, 2016

IZVOD Biodizel, alternativno gorivo fosilnim, dobija se reakcijom transesterifikacije triacilglic... more IZVOD Biodizel, alternativno gorivo fosilnim, dobija se reakcijom transesterifikacije triacilglicerola iz biljnih ulja i životinjskih masti nižim alifatičnim alkoholima. I pored brojnih prednosti u odnosu na fosilna goriva, glavna prepreka široj komercijalnoj upotrebi biodizela je visoka cena jestivih biljnih ulja. U poslednje vreme, posebnu pažnju zaslužuju nusproizvodi industrije proizvodnje jestivih ulja kao izvori triacilglicerola, jer se njihovim korišćenjem ostvaruju pozitivni ekonomski i ekološki efekti. U radu su analizirani postupci dobijanja biodizela iz nusproizvoda procesa rafinacije jestivih ulja (sapunske smeše, otpadna zemlja za beljenje, deodorisani destilat), sa osvrtom na faktore koji utiču na reakciju sinteze estara masnih kiselina. Cilj rada je da se istraže mogućnosti korišćenja ovih otpadnih sirovina u proizvodnji biodizela.

Fuel, May 31, 2013

ABSTRACT h i g h l i g h t s " KOH and CaO catalyze the sunflower oil methanolysis in th... more ABSTRACT h i g h l i g h t s " KOH and CaO catalyze the sunflower oil methanolysis in the presence of cosolvents. " Tetrahydrofuran favors the triacylglycerol mass transfer by reducing drop size. " The CaO-catalyzed methanolysis is not speeded up with the use of cosolvents. a b s t r a c t Homogeneously and heterogeneously base-catalyzed sunflower oil methanolysis was investigated with-out and with the presence of the cosolvents. In the former case, KOH and tetrahydrofuran (THF) were used as a catalyst and a cosolvent, respectively, and the reaction was performed at the reaction temper-ature of 10 °C and the methanol-to-oil molar ratio of 6:1. In the latter case, CaO and various organic sol-vents such as THF, n-hexane, dioxane, diethyl ether, triethanolamine, ethyl acetate and methyl ethyl ketone were employed as a solid catalyst and a cosolvent, respectively, and the reaction was carried out at the reaction temperature of 60 °C and the methanol-to-oil molar ratio of 6:1. The rate of KOH-catalyzed sunflower oil methanolysis increased with increasing the THF concentration up to 50% of the oil mass, which was due to the self-enhancement of the interfacial area as the result of decreasing the mean drop size. No effect of THF present at the concentration of 20% on the rate of CaO-catalyzed methanolysis was observed, but at higher THF concentrations, the reaction was delayed and the final fatty acid methyl esters (FAME) yield was decreased. Of all tested cosolvents, only n-hexane and THF slightly improved the methanolysis reaction in its initial period, triethanolamine and ethyl acetate had no effect, while diethyl ether, dioxane and methyl ethyl ketone negatively influenced the reaction rate and the FAME yield.

h i g h l i g h t s " Four operational factors included in optimization of methanolysis under son... more h i g h l i g h t s " Four operational factors included in optimization of methanolysis under sonication. " Comparing the performances of RSM and ANN in optimizing biodiesel production process. " ANN predictions of FAME yield (±3.4%) were much better than those of RSM (±24.2%). " The generalization ability of the developed ANN model was well documented.

Ultrasonics Sonochemistry, 2013

In this paper, extraction of resinoid from the aerial parts of white lady&amp... more In this paper, extraction of resinoid from the aerial parts of white lady's bedstraw (Galium mollugo L.) using an aqueous ethanol solution (50% by volume) was studied at different temperatures in the absence and the presence of ultrasound. This study indicated that ultrasound-assisted extraction was effective for extracting the resinoid and gave better resinoid yields at lower extraction temperature and in much shorter time than the maceration. A phenomenological model was developed for modeling the kinetics of the extraction process. The model successfully describes the two-step extraction consisting of washing followed by diffusion of extractable substances and shows that ultrasound influences only the first step. The extraction process was optimized using response surface methodology (RMS) and artificial neural network (ANN) models. For the former modeling, the second-order polynomial equation was applied, while the second one was performed by an ANN-GA combination. The high coefficient of determination and the low MRPD between the ANN prediction and the corresponding experimental data proved that modeling the extraction process in the absence and the presence of ultrasound using ANN was more accurate than RSM modeling. The optimum extraction temperature was determined to be 80 and 40 °C, respectively for the maceration and the ultrasound-assisted extraction, ensuring the highest resinoid yield of 22.0 g/100g in 4h and 25.1g/100g in 30 min, which agreed with the yields obtained experimentally for the same time (21.7 and 25.3g/100g, respectively).

Chemical Industry and Chemical Engineering Quarterly, 2016

Article Highlights • Ethanolysis of sunflower oil over CaO was studied • Kinetics included the ch... more Article Highlights • Ethanolysis of sunflower oil over CaO was studied • Kinetics included the changing reaction mechanism with respect to triacylglycerols • The kinetic parameters were correlated with the process variables • A good agreement of the kinetic model with the experimental data was observed

Waste Management, 2016

This study reports on the use of oil obtained from waste plum stones as a low-cost feedstock for ... more This study reports on the use of oil obtained from waste plum stones as a low-cost feedstock for biodiesel production. Because of high free fatty acid (FFA) level (15.8%), the oil was processed through the two-step process including esterification of FFA and methanolysis of the esterified oil catalyzed by H2SO4 and CaO, respectively. Esterification was optimized by response surface methodology combined with a central composite design. The second-order polynomial equation predicted the lowest acid value of 0.53mgKOH/g under the following optimal reaction conditions: the methanol:oil molar ratio of 8.5:1, the catalyst amount of 2% and the reaction temperature of 45°C. The predicted acid value agreed with the experimental acid value (0.47mgKOH/g). The kinetics of FFA esterification was described by the irreversible pseudo first-order reaction rate law. The apparent kinetic constant was correlated with the initial methanol and catalyst concentrations and reaction temperature. The activation energy of the esterification reaction slightly decreased from 13.23 to 11.55kJ/mol with increasing the catalyst concentration from 0.049 to 0.172mol/dm(3). In the second step, the esterified oil reacted with methanol (methanol:oil molar ratio of 9:1) in the presence of CaO (5% to the oil mass) at 60°C. The properties of the obtained biodiesel were within the EN 14214 standard limits. Hence, waste plum stones might be valuable raw material for obtaining fatty oil for the use as alternative feedstock in biodiesel production.

Fuel Processing Technology, Nov 1, 2010

The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at differe... more The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at different reaction conditions. A full factorial experiment 3 3 with replication was performed. The effects of three reaction variables, methanol-to-oil molar ratio, catalyst loading and the reaction ...

Savremene tehnologije, 2015

The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a meth... more The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a methanol:WCO molar ratio of 6:1, the initial KOH amount of 1% (based on the oil weight) and moderate temperatures (30 o C to 60 o C) with the aim to model the methanolysis reaction kinetics. It was observed that the methanolysis reaction occurred via a pseudo-homogeneous regime where the chemical reaction controls the overall process kinetics and with no mass transfer limitation. It was shown that irreversible pseudo-first and-second order reactions were reliable for describing the methanolysis reaction. However, a better fitting of experimental data was observed by using the irreversible pseudo-second order kinetic model. The reaction rate constant increased with increasing the reaction temperature and at 60 o C the WCO conversion of 97% was achieved in 3 minutes. The final products satisfied the EN 14214 biodiesel standard specifications.

Chemical Industry and Chemical Engineering Quarterly, 2015

Article Highlights • Kinetics of methanolysis reaction catalyzed by calcium-based catalysts • Kin... more Article Highlights • Kinetics of methanolysis reaction catalyzed by calcium-based catalysts • Kinetic model involves TAG mass transfer and chemically controlled regions • Effects of reaction conditions on parameters of the kinetic models are analyzed

Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odn... more Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odnosi se na izvođenje metanolize biljnih ulja katalizovane kalcijum oksidom u šaržnim uslovima i na pripremu kalcijum oksida za katalizu reakcije metanolize. Prema Međunarodnoj klasifikaciji patenata oznaka je: C 07 C 67/02, 69/00. Tehnički problem Biodizel je komercijalni naziv za smešu alkil estara viših masnih kiselina standardizovanog kvaliteta (JUS EN 14214, EN 14214). Estri masnih kiselina se najčešće dobijaju reakcijom alkoholize triglicerida biljnih ulja ili životinjskih masti i nižih alifatičnih alkohola. Reakcija alkoholize je povratna i odigrava se u prisustvu viška alkohola i katalizatora ili u odsustvu katalizatora pod ekstremno visokim uslovima pritiska i temperature (iznad kritičnih uslova za alkohol). Katalizatori reakcije alkoholize su baze, kiseline i enzimi. Najčešće primenjivani postupak sinteze alkil estara u industrijskim uslovima je alkoholiza biljnih ulja u prisustv...

Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odn... more Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odnosi se na izvođenje reakcije bazno katalizovane alkoholize biljnih ulja u dvostepenom reaktorskom sistemu sa dva protočna reaktora sa vibracionom mešalicom (RVM) sa kontinualnim radom. Prema Međunarodnoj klasifikaciji patenata oznaka je: C11C 3/10. Tehnički problem Estri masnih kiselina dobijaju se katalizovanom (bazno, kiselinski ili enzimski) reakcijom alkoholize biljnih ulja i životinjskih masti, koja se može prikazati sledećom sumarnom stehiometrijskom jednačinom: U industrijskoj proizvodnji, koriste se uglavnom biljna ulja i metanol, kao reaktanti, i kalijum ili natrijum hidroksid, kao katalizator, pa je glavni proizvod smeša metil estara masnih kiselina. Smeše metil estara masnih kiselina sa osobinama koje odgovaraju standardu (na primer, JUS EN 14214, EN 14214 i ASTMPS 121-99) poznate se pod imenom biodizel, koji je alternativa dizel gorivu. Relativno mali prinos estara masnih kis...

Energy Conversion and Management, 2015

ABSTRACT

Chemical Engineering & Technology, 2015

ABSTRACT

Savremene tehnologije, 2014

The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a meth... more The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a methanol:WCO molar ratio of 6:1, the initial KOH amount of 1% (based on the oil weight) and moderate temperatures (30 o C to 60 o C) with the aim to model the methanolysis reaction kinetics. It was observed that the methanolysis reaction occurred via a pseudo-homogeneous regime where the chemical reaction controls the overall process kinetics and with no mass transfer limitation. It was shown that irreversible pseudo-first and-second order reactions were reliable for describing the methanolysis reaction. However, a better fitting of experimental data was observed by using the irreversible pseudo-second order kinetic model. The reaction rate constant increased with increasing the reaction temperature and at 60 o C the WCO conversion of 97% was achieved in 3 minutes. The final products satisfied the EN 14214 biodiesel standard specifications.

Renewable and Sustainable Energy Reviews, 2015

ABSTRACT This review paper presents the methods that have been used to date for the purification ... more ABSTRACT This review paper presents the methods that have been used to date for the purification of crude biodiesel obtained by heterogeneous production processes. At first, a typical biodiesel production process using heterogeneous catalysts is shortly described, paying attention to the main processing steps. Then, possible impurities and their effects on the biodiesel quality are pointed out. The main part of this review paper deals with the traditional (wet and dry washing) and novel (membrane extraction, precipitation, complexation, simultaneous ion-exchange and precipitation as well as simultaneous biodiesel synthesis and purification) purification methods. These purification methods are compared with respect of their refining efficiency. A special attention is paid to their comparison regarding the type of raw materials used in biodiesel production. Furthermore, advantages and disadvantages of the crude biodiesel purification methods are emphasized. Finally, environmental aspects of crude biodiesel purification are highlighted.

Fuel, 2015

ABSTRACT The continuous sunflower oil methanolysis catalyzed by quicklime in a packed-bed tubular... more ABSTRACT The continuous sunflower oil methanolysis catalyzed by quicklime in a packed-bed tubular reactor of 60 cm height was studied at 60 °C using methanol-to-oil molar ratios from 6:1 to 18:1 and weight hourly space velocities from 0.188 to 0.376 (kg/kgcat h). The main goal was to establish the effect of the process variables on the fatty acid methyl esters (FAME) synthesis. A full factorial design was used to evaluate the significance of the three process factors (methanol-to-oil molar ratio, flow rate of the reactants and bed height) statistically. Moreover, the recently reported kinetic model of methanolysis was used to describe variations of FAME and triacylglycerols (TAG) concentrations along the reactor length. The kinetic model predicted the axial concentration profiles of TAG and FAME in the reactor with acceptable accuracy. A high FAME content (98.5%) could be achieved at the two thirds of the bed of quicklime bits without loss of catalytic activity within 30 h of continuous operation.

Chemical Industry

Triethanolamine was applied as an efficient "green" cosolvent for biodiesel production by CaOcata... more Triethanolamine was applied as an efficient "green" cosolvent for biodiesel production by CaOcatalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4 °C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75 °C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.

Fuel

Crude biodiesel was proven as a cosolvent in the methanolysis of sunflower oil catalyzed by calci... more Crude biodiesel was proven as a cosolvent in the methanolysis of sunflower oil catalyzed by calcined CaO. This reaction was modeled and optimized statistically in terms of reaction temperature (33.2–66.8 °C), methanol-to-oil molar ratio (3.5:1–8.5:1) and catalyst concentration (0.219–1.065 mol/L). The cosolvent loading was 10 wt% (based on oil weight). The optimum reaction conditions were found to be: the methanol-to-oil molar ratio of 7.1:1, the catalyst concentration of 0.74 mol/L and the reaction temperature 52 °C, ensuring the best esters content of 99.8%, for the reaction time of 1.5 h, which is close to the reported experimental value of 98.9%. Also, the used catalyst was recycled with no additional treatment in the further four consecutive cycles under the following reaction conditions: methanol-to-oil molar ratio 6:1, the concentration of catalyst 0.642 mol/L (only in the first run), the reaction temperature 50 °C, cosolvent-crude biodiesel loading 10 wt% to oil weight. The second recycling reaction provided the highest FAME content of 97.7% after 5 h.

Journal of the Serbian Chemical Society

Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-he... more Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 ?C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol?L-1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7?1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two prov...

Reciklaza i odrzivi razvoj, 2016

IZVOD Biodizel, alternativno gorivo fosilnim, dobija se reakcijom transesterifikacije triacilglic... more IZVOD Biodizel, alternativno gorivo fosilnim, dobija se reakcijom transesterifikacije triacilglicerola iz biljnih ulja i životinjskih masti nižim alifatičnim alkoholima. I pored brojnih prednosti u odnosu na fosilna goriva, glavna prepreka široj komercijalnoj upotrebi biodizela je visoka cena jestivih biljnih ulja. U poslednje vreme, posebnu pažnju zaslužuju nusproizvodi industrije proizvodnje jestivih ulja kao izvori triacilglicerola, jer se njihovim korišćenjem ostvaruju pozitivni ekonomski i ekološki efekti. U radu su analizirani postupci dobijanja biodizela iz nusproizvoda procesa rafinacije jestivih ulja (sapunske smeše, otpadna zemlja za beljenje, deodorisani destilat), sa osvrtom na faktore koji utiču na reakciju sinteze estara masnih kiselina. Cilj rada je da se istraže mogućnosti korišćenja ovih otpadnih sirovina u proizvodnji biodizela.

Fuel, May 31, 2013

ABSTRACT h i g h l i g h t s " KOH and CaO catalyze the sunflower oil methanolysis in th... more ABSTRACT h i g h l i g h t s " KOH and CaO catalyze the sunflower oil methanolysis in the presence of cosolvents. " Tetrahydrofuran favors the triacylglycerol mass transfer by reducing drop size. " The CaO-catalyzed methanolysis is not speeded up with the use of cosolvents. a b s t r a c t Homogeneously and heterogeneously base-catalyzed sunflower oil methanolysis was investigated with-out and with the presence of the cosolvents. In the former case, KOH and tetrahydrofuran (THF) were used as a catalyst and a cosolvent, respectively, and the reaction was performed at the reaction temper-ature of 10 °C and the methanol-to-oil molar ratio of 6:1. In the latter case, CaO and various organic sol-vents such as THF, n-hexane, dioxane, diethyl ether, triethanolamine, ethyl acetate and methyl ethyl ketone were employed as a solid catalyst and a cosolvent, respectively, and the reaction was carried out at the reaction temperature of 60 °C and the methanol-to-oil molar ratio of 6:1. The rate of KOH-catalyzed sunflower oil methanolysis increased with increasing the THF concentration up to 50% of the oil mass, which was due to the self-enhancement of the interfacial area as the result of decreasing the mean drop size. No effect of THF present at the concentration of 20% on the rate of CaO-catalyzed methanolysis was observed, but at higher THF concentrations, the reaction was delayed and the final fatty acid methyl esters (FAME) yield was decreased. Of all tested cosolvents, only n-hexane and THF slightly improved the methanolysis reaction in its initial period, triethanolamine and ethyl acetate had no effect, while diethyl ether, dioxane and methyl ethyl ketone negatively influenced the reaction rate and the FAME yield.

h i g h l i g h t s " Four operational factors included in optimization of methanolysis under son... more h i g h l i g h t s " Four operational factors included in optimization of methanolysis under sonication. " Comparing the performances of RSM and ANN in optimizing biodiesel production process. " ANN predictions of FAME yield (±3.4%) were much better than those of RSM (±24.2%). " The generalization ability of the developed ANN model was well documented.

Ultrasonics Sonochemistry, 2013

In this paper, extraction of resinoid from the aerial parts of white lady&amp... more In this paper, extraction of resinoid from the aerial parts of white lady's bedstraw (Galium mollugo L.) using an aqueous ethanol solution (50% by volume) was studied at different temperatures in the absence and the presence of ultrasound. This study indicated that ultrasound-assisted extraction was effective for extracting the resinoid and gave better resinoid yields at lower extraction temperature and in much shorter time than the maceration. A phenomenological model was developed for modeling the kinetics of the extraction process. The model successfully describes the two-step extraction consisting of washing followed by diffusion of extractable substances and shows that ultrasound influences only the first step. The extraction process was optimized using response surface methodology (RMS) and artificial neural network (ANN) models. For the former modeling, the second-order polynomial equation was applied, while the second one was performed by an ANN-GA combination. The high coefficient of determination and the low MRPD between the ANN prediction and the corresponding experimental data proved that modeling the extraction process in the absence and the presence of ultrasound using ANN was more accurate than RSM modeling. The optimum extraction temperature was determined to be 80 and 40 °C, respectively for the maceration and the ultrasound-assisted extraction, ensuring the highest resinoid yield of 22.0 g/100g in 4h and 25.1g/100g in 30 min, which agreed with the yields obtained experimentally for the same time (21.7 and 25.3g/100g, respectively).

Chemical Industry and Chemical Engineering Quarterly, 2016

Article Highlights • Ethanolysis of sunflower oil over CaO was studied • Kinetics included the ch... more Article Highlights • Ethanolysis of sunflower oil over CaO was studied • Kinetics included the changing reaction mechanism with respect to triacylglycerols • The kinetic parameters were correlated with the process variables • A good agreement of the kinetic model with the experimental data was observed

Waste Management, 2016

This study reports on the use of oil obtained from waste plum stones as a low-cost feedstock for ... more This study reports on the use of oil obtained from waste plum stones as a low-cost feedstock for biodiesel production. Because of high free fatty acid (FFA) level (15.8%), the oil was processed through the two-step process including esterification of FFA and methanolysis of the esterified oil catalyzed by H2SO4 and CaO, respectively. Esterification was optimized by response surface methodology combined with a central composite design. The second-order polynomial equation predicted the lowest acid value of 0.53mgKOH/g under the following optimal reaction conditions: the methanol:oil molar ratio of 8.5:1, the catalyst amount of 2% and the reaction temperature of 45°C. The predicted acid value agreed with the experimental acid value (0.47mgKOH/g). The kinetics of FFA esterification was described by the irreversible pseudo first-order reaction rate law. The apparent kinetic constant was correlated with the initial methanol and catalyst concentrations and reaction temperature. The activation energy of the esterification reaction slightly decreased from 13.23 to 11.55kJ/mol with increasing the catalyst concentration from 0.049 to 0.172mol/dm(3). In the second step, the esterified oil reacted with methanol (methanol:oil molar ratio of 9:1) in the presence of CaO (5% to the oil mass) at 60°C. The properties of the obtained biodiesel were within the EN 14214 standard limits. Hence, waste plum stones might be valuable raw material for obtaining fatty oil for the use as alternative feedstock in biodiesel production.

Fuel Processing Technology, Nov 1, 2010

The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at differe... more The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at different reaction conditions. A full factorial experiment 3 3 with replication was performed. The effects of three reaction variables, methanol-to-oil molar ratio, catalyst loading and the reaction ...

Savremene tehnologije, 2015

The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a meth... more The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a methanol:WCO molar ratio of 6:1, the initial KOH amount of 1% (based on the oil weight) and moderate temperatures (30 o C to 60 o C) with the aim to model the methanolysis reaction kinetics. It was observed that the methanolysis reaction occurred via a pseudo-homogeneous regime where the chemical reaction controls the overall process kinetics and with no mass transfer limitation. It was shown that irreversible pseudo-first and-second order reactions were reliable for describing the methanolysis reaction. However, a better fitting of experimental data was observed by using the irreversible pseudo-second order kinetic model. The reaction rate constant increased with increasing the reaction temperature and at 60 o C the WCO conversion of 97% was achieved in 3 minutes. The final products satisfied the EN 14214 biodiesel standard specifications.

Chemical Industry and Chemical Engineering Quarterly, 2015

Article Highlights • Kinetics of methanolysis reaction catalyzed by calcium-based catalysts • Kin... more Article Highlights • Kinetics of methanolysis reaction catalyzed by calcium-based catalysts • Kinetic model involves TAG mass transfer and chemically controlled regions • Effects of reaction conditions on parameters of the kinetic models are analyzed

Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odn... more Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odnosi se na izvođenje metanolize biljnih ulja katalizovane kalcijum oksidom u šaržnim uslovima i na pripremu kalcijum oksida za katalizu reakcije metanolize. Prema Međunarodnoj klasifikaciji patenata oznaka je: C 07 C 67/02, 69/00. Tehnički problem Biodizel je komercijalni naziv za smešu alkil estara viših masnih kiselina standardizovanog kvaliteta (JUS EN 14214, EN 14214). Estri masnih kiselina se najčešće dobijaju reakcijom alkoholize triglicerida biljnih ulja ili životinjskih masti i nižih alifatičnih alkohola. Reakcija alkoholize je povratna i odigrava se u prisustvu viška alkohola i katalizatora ili u odsustvu katalizatora pod ekstremno visokim uslovima pritiska i temperature (iznad kritičnih uslova za alkohol). Katalizatori reakcije alkoholize su baze, kiseline i enzimi. Najčešće primenjivani postupak sinteze alkil estara u industrijskim uslovima je alkoholiza biljnih ulja u prisustv...

Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odn... more Oblast tehnike na koju se pronalazak odnosi Pronalazak pripada oblasti hemijske tehnologije i odnosi se na izvođenje reakcije bazno katalizovane alkoholize biljnih ulja u dvostepenom reaktorskom sistemu sa dva protočna reaktora sa vibracionom mešalicom (RVM) sa kontinualnim radom. Prema Međunarodnoj klasifikaciji patenata oznaka je: C11C 3/10. Tehnički problem Estri masnih kiselina dobijaju se katalizovanom (bazno, kiselinski ili enzimski) reakcijom alkoholize biljnih ulja i životinjskih masti, koja se može prikazati sledećom sumarnom stehiometrijskom jednačinom: U industrijskoj proizvodnji, koriste se uglavnom biljna ulja i metanol, kao reaktanti, i kalijum ili natrijum hidroksid, kao katalizator, pa je glavni proizvod smeša metil estara masnih kiselina. Smeše metil estara masnih kiselina sa osobinama koje odgovaraju standardu (na primer, JUS EN 14214, EN 14214 i ASTMPS 121-99) poznate se pod imenom biodizel, koji je alternativa dizel gorivu. Relativno mali prinos estara masnih kis...

Energy Conversion and Management, 2015

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Chemical Engineering & Technology, 2015

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Savremene tehnologije, 2014

The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a meth... more The homogeneous base-catalyzed methanolysis of waste cooking oil (WCO) was investigated at a methanol:WCO molar ratio of 6:1, the initial KOH amount of 1% (based on the oil weight) and moderate temperatures (30 o C to 60 o C) with the aim to model the methanolysis reaction kinetics. It was observed that the methanolysis reaction occurred via a pseudo-homogeneous regime where the chemical reaction controls the overall process kinetics and with no mass transfer limitation. It was shown that irreversible pseudo-first and-second order reactions were reliable for describing the methanolysis reaction. However, a better fitting of experimental data was observed by using the irreversible pseudo-second order kinetic model. The reaction rate constant increased with increasing the reaction temperature and at 60 o C the WCO conversion of 97% was achieved in 3 minutes. The final products satisfied the EN 14214 biodiesel standard specifications.

Renewable and Sustainable Energy Reviews, 2015

ABSTRACT This review paper presents the methods that have been used to date for the purification ... more ABSTRACT This review paper presents the methods that have been used to date for the purification of crude biodiesel obtained by heterogeneous production processes. At first, a typical biodiesel production process using heterogeneous catalysts is shortly described, paying attention to the main processing steps. Then, possible impurities and their effects on the biodiesel quality are pointed out. The main part of this review paper deals with the traditional (wet and dry washing) and novel (membrane extraction, precipitation, complexation, simultaneous ion-exchange and precipitation as well as simultaneous biodiesel synthesis and purification) purification methods. These purification methods are compared with respect of their refining efficiency. A special attention is paid to their comparison regarding the type of raw materials used in biodiesel production. Furthermore, advantages and disadvantages of the crude biodiesel purification methods are emphasized. Finally, environmental aspects of crude biodiesel purification are highlighted.

Fuel, 2015

ABSTRACT The continuous sunflower oil methanolysis catalyzed by quicklime in a packed-bed tubular... more ABSTRACT The continuous sunflower oil methanolysis catalyzed by quicklime in a packed-bed tubular reactor of 60 cm height was studied at 60 °C using methanol-to-oil molar ratios from 6:1 to 18:1 and weight hourly space velocities from 0.188 to 0.376 (kg/kgcat h). The main goal was to establish the effect of the process variables on the fatty acid methyl esters (FAME) synthesis. A full factorial design was used to evaluate the significance of the three process factors (methanol-to-oil molar ratio, flow rate of the reactants and bed height) statistically. Moreover, the recently reported kinetic model of methanolysis was used to describe variations of FAME and triacylglycerols (TAG) concentrations along the reactor length. The kinetic model predicted the axial concentration profiles of TAG and FAME in the reactor with acceptable accuracy. A high FAME content (98.5%) could be achieved at the two thirds of the bed of quicklime bits without loss of catalytic activity within 30 h of continuous operation.