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Guanghui Dai - One of the best experts on this subject based on the ideXlab platform.
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carmine spider mite tetranychus cinnabarinus control laboratory and field efficacy and biochemical characterization of 2 4 di tertbutylphenol and Ethyl Oleate
Crop Protection, 2021Co-Authors: Yijuan Chen, Jiaxuan Luo, Nianfeng Wan, Jiexian Jiang, Guanghui DaiAbstract:Abstract Natural pesticides are potential alternatives to conventional chemical pesticides. Recently, studies on pesticide–pest interactions have combined empirical biochemical measurements and practical field experiments. In this study, we performed laboratory and field efficacy analysis and biochemical characterization of two phytochemicals (2,4-di-tertbutylphenol (DTBP) and Ethyl Oleate (EO)) for carmine spider mite Tetranychus cinnabarinus control. DTBP and EO controlled mites by inhibiting egg hatchability and showed significant residual toxicity in laboratory tests. The control efficacy was confirmed in eggplant and cucumber field trials in three provinces in China. Oxidative stress induced by antioxidant enzymes (superoxide dismutase and peroxidase) and detoxification metabolism (involving carboxylesterase and/or mixed-function oxidase) may be involved in the response of mites to DTBP and EO. This study demonstrates the potential of DTBP and EO as effective acaricides for the control of spider mites and provides researchers a better understanding of acaricide–mite interactions.
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biochemical mechanisms of acaricidal activity of 2 4 di tert butylphenol and Ethyl Oleate against the carmine spider mite tetranychus cinnabarinus
Journal of Pest Science, 2018Co-Authors: Yijuan Chen, Cedric Bertrand, Guanghui Dai, Jiaojian YuanAbstract:Tetranychus cinnabarinus (Boisduval) is one of the most economically important and highly polyphagous herbivorous pests in fields and greenhouses worldwide. We previously reported that 2,4-di-tert-butylphenol (DTBP) and Ethyl Oleate (EO) showed significantly acaricidal, repellent and oviposition deterrent properties against T. cinnabarinus via an unknown mechanism. In this study, the acaricidal activities of DTBP and EO and their biochemical mechanisms in controlling T. cinnabarinus were investigated at different time points by assessing the associated changes in toxic symptoms, potential target-related enzyme activities and seven neurotransmitters belonging to the biogenic amines (BAs). The results showed that the median lethal times (LT50) for DTBP and EO were 8 and 15 h after treatment, respectively. Using dynamic symptomatology observations, typical neurotoxic symptoms including excitation, convulsion and paralysis were observed in the mites treated with DTBP and EO. Furthermore, the two compounds exerted significant inhibitory activity on monoamine oxidase (MAO) in adult T. cinnabarinus females in vitro and in vivo and had little effect on acetylcholinesterase (AChE) activity. The content levels of the seven BAs analyzed by UPLC-3QMS were higher in the mites treated with DTBP and EO than in the controls, except for phenEthylamine (PEA) (for DTBP and EO) and octopamine (OA) (for EO). These results demonstrate that both DTBP and EO exert effects on T. cinnabarinus that are possibly consequences of their preventive effects on the deamination of BAs in the nervous system, most likely through inhibitory effects on MAO or MAO-like enzymes and/or interactions with certain special biogenic amine G protein-coupled receptors.
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acaricidal activity of compounds from cinnamomum camphora l presl against the carmine spider mite tetranychus cinnabarinus
Pest Management Science, 2015Co-Authors: Yijuan Chen, Guanghui DaiAbstract:BACKGROUND Tetranychus cinnabarinus (Boisduval) is one of the most important, highly polyphagous pests of a wide range of field and greenhouse crops throughout the world. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, we screened eight plant extracts from China and evaluated the natural compounds showing acaricidal properties from the plant extract, considering their potential use as an alternative to synthetic pesticides. RESULTS In bioassay screening assays, the Cinnamomum camphora (L.) Presl extract showed significantly greater acaricidal activity against T. cinnabarinus than the other seven plant extracts tested. Five compounds were identified from the C. camphora extract via repeated column chromatography and gas chromatography–mass spectrometry analysis. All the compounds presented acaricidal activity, with 2,4-di-tert-butylphenol and Ethyl Oleate exhibiting the greatest activity. At 7 days after treatment in a potted seedling experiment, the LC50 values of 2,4-di-tert-butylphenol and Ethyl Oleate were found to be 1850.94 and 2481.65 mg kg−1 respectively. Microscopic observations showed that the mites displayed the symptomology of poisoning. CONCLUSION These results demonstrated that the C. camphora extract and its two active components show the potential to be developed as new natural acaricides for controlling carmine spider mites. © 2014 Society of Chemical Industry
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acaricidal repellent and oviposition deterrent activities of 2 4 di tert butylphenol and Ethyl Oleate against the carmine spider mite tetranychus cinnabarinus
Journal of Pest Science, 2015Co-Authors: Yijuan Chen, Guanghui DaiAbstract:Tetranychus cinnabarinus (Boisduval) is highly polyphagous and is considered one of the most important crop pests, infesting over 100 crop species grown in field and greenhouse crops worldwide. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, 2,4-di-tert-butylphenol (DTBP) and Ethyl Oleate (EO) were investigated for their acaricidal, repellent, and oviposition-deterrent properties against T. cinnabarinus under laboratory conditions. Both DTBP and EO exhibited significantly adulticidal, larvicidal, and ovi- cidal activities against T. cinnabarinus in a concentration- dependent manner after treatment, with LC50 values of 1,256.51, 625.39, and 743.64 ppm for DTBP and 1,621.57, 859.25, and 987.26 ppm for EO, respectively. The mites exhibited the highest run-off rate on bean leaf surfaces sprayed with both DTBP and EO when applied at sub- lethal doses and moved toward surfaces that had not been sprayed with these compounds, according to Pearson's v 2 test. Furthermore, not only in a choice assay but also in a no-choice assay, a significant difference was found using an ANOVA between the numbers of eggs laid on bean leaves that were sprayed with DTBP and EO at sub-lethal doses compared to the number laid on unsprayed bean leaves. Additionally, stability assays revealed that EO was more sensitive to environmental factors than DTBP. These results demonstrate that the two compounds DTBP and EO have potential for development as new, natural acaricides for controlling carmine spider mites.
Yijuan Chen - One of the best experts on this subject based on the ideXlab platform.
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carmine spider mite tetranychus cinnabarinus control laboratory and field efficacy and biochemical characterization of 2 4 di tertbutylphenol and Ethyl Oleate
Crop Protection, 2021Co-Authors: Yijuan Chen, Jiaxuan Luo, Nianfeng Wan, Jiexian Jiang, Guanghui DaiAbstract:Abstract Natural pesticides are potential alternatives to conventional chemical pesticides. Recently, studies on pesticide–pest interactions have combined empirical biochemical measurements and practical field experiments. In this study, we performed laboratory and field efficacy analysis and biochemical characterization of two phytochemicals (2,4-di-tertbutylphenol (DTBP) and Ethyl Oleate (EO)) for carmine spider mite Tetranychus cinnabarinus control. DTBP and EO controlled mites by inhibiting egg hatchability and showed significant residual toxicity in laboratory tests. The control efficacy was confirmed in eggplant and cucumber field trials in three provinces in China. Oxidative stress induced by antioxidant enzymes (superoxide dismutase and peroxidase) and detoxification metabolism (involving carboxylesterase and/or mixed-function oxidase) may be involved in the response of mites to DTBP and EO. This study demonstrates the potential of DTBP and EO as effective acaricides for the control of spider mites and provides researchers a better understanding of acaricide–mite interactions.
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biochemical mechanisms of acaricidal activity of 2 4 di tert butylphenol and Ethyl Oleate against the carmine spider mite tetranychus cinnabarinus
Journal of Pest Science, 2018Co-Authors: Yijuan Chen, Cedric Bertrand, Guanghui Dai, Jiaojian YuanAbstract:Tetranychus cinnabarinus (Boisduval) is one of the most economically important and highly polyphagous herbivorous pests in fields and greenhouses worldwide. We previously reported that 2,4-di-tert-butylphenol (DTBP) and Ethyl Oleate (EO) showed significantly acaricidal, repellent and oviposition deterrent properties against T. cinnabarinus via an unknown mechanism. In this study, the acaricidal activities of DTBP and EO and their biochemical mechanisms in controlling T. cinnabarinus were investigated at different time points by assessing the associated changes in toxic symptoms, potential target-related enzyme activities and seven neurotransmitters belonging to the biogenic amines (BAs). The results showed that the median lethal times (LT50) for DTBP and EO were 8 and 15 h after treatment, respectively. Using dynamic symptomatology observations, typical neurotoxic symptoms including excitation, convulsion and paralysis were observed in the mites treated with DTBP and EO. Furthermore, the two compounds exerted significant inhibitory activity on monoamine oxidase (MAO) in adult T. cinnabarinus females in vitro and in vivo and had little effect on acetylcholinesterase (AChE) activity. The content levels of the seven BAs analyzed by UPLC-3QMS were higher in the mites treated with DTBP and EO than in the controls, except for phenEthylamine (PEA) (for DTBP and EO) and octopamine (OA) (for EO). These results demonstrate that both DTBP and EO exert effects on T. cinnabarinus that are possibly consequences of their preventive effects on the deamination of BAs in the nervous system, most likely through inhibitory effects on MAO or MAO-like enzymes and/or interactions with certain special biogenic amine G protein-coupled receptors.
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acaricidal activity of compounds from cinnamomum camphora l presl against the carmine spider mite tetranychus cinnabarinus
Pest Management Science, 2015Co-Authors: Yijuan Chen, Guanghui DaiAbstract:BACKGROUND Tetranychus cinnabarinus (Boisduval) is one of the most important, highly polyphagous pests of a wide range of field and greenhouse crops throughout the world. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, we screened eight plant extracts from China and evaluated the natural compounds showing acaricidal properties from the plant extract, considering their potential use as an alternative to synthetic pesticides. RESULTS In bioassay screening assays, the Cinnamomum camphora (L.) Presl extract showed significantly greater acaricidal activity against T. cinnabarinus than the other seven plant extracts tested. Five compounds were identified from the C. camphora extract via repeated column chromatography and gas chromatography–mass spectrometry analysis. All the compounds presented acaricidal activity, with 2,4-di-tert-butylphenol and Ethyl Oleate exhibiting the greatest activity. At 7 days after treatment in a potted seedling experiment, the LC50 values of 2,4-di-tert-butylphenol and Ethyl Oleate were found to be 1850.94 and 2481.65 mg kg−1 respectively. Microscopic observations showed that the mites displayed the symptomology of poisoning. CONCLUSION These results demonstrated that the C. camphora extract and its two active components show the potential to be developed as new natural acaricides for controlling carmine spider mites. © 2014 Society of Chemical Industry
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acaricidal repellent and oviposition deterrent activities of 2 4 di tert butylphenol and Ethyl Oleate against the carmine spider mite tetranychus cinnabarinus
Journal of Pest Science, 2015Co-Authors: Yijuan Chen, Guanghui DaiAbstract:Tetranychus cinnabarinus (Boisduval) is highly polyphagous and is considered one of the most important crop pests, infesting over 100 crop species grown in field and greenhouse crops worldwide. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, 2,4-di-tert-butylphenol (DTBP) and Ethyl Oleate (EO) were investigated for their acaricidal, repellent, and oviposition-deterrent properties against T. cinnabarinus under laboratory conditions. Both DTBP and EO exhibited significantly adulticidal, larvicidal, and ovi- cidal activities against T. cinnabarinus in a concentration- dependent manner after treatment, with LC50 values of 1,256.51, 625.39, and 743.64 ppm for DTBP and 1,621.57, 859.25, and 987.26 ppm for EO, respectively. The mites exhibited the highest run-off rate on bean leaf surfaces sprayed with both DTBP and EO when applied at sub- lethal doses and moved toward surfaces that had not been sprayed with these compounds, according to Pearson's v 2 test. Furthermore, not only in a choice assay but also in a no-choice assay, a significant difference was found using an ANOVA between the numbers of eggs laid on bean leaves that were sprayed with DTBP and EO at sub-lethal doses compared to the number laid on unsprayed bean leaves. Additionally, stability assays revealed that EO was more sensitive to environmental factors than DTBP. These results demonstrate that the two compounds DTBP and EO have potential for development as new, natural acaricides for controlling carmine spider mites.
Maria Lujan Ferreira - One of the best experts on this subject based on the ideXlab platform.
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kinetic modeling of enzymatic Ethyl Oleate synthesis carried out in biphasic systems
Applied Catalysis A-general, 2008Co-Authors: Maria Laura Foresti, Maria Lujan Ferreira, M Pedernera, Veronica BucalaAbstract:This work presents a new approach for the kinetic modeling of solvent free Ethyl Oleate synthesis, catalyzed by an enzymatic catalyst. The biocatalyst used was the lipase from Candida antarctica B immobilized onto chitosan powder. Thermodynamic calculations revealed that the addition of water to hydrate the biocatalyst, or the production of water during esterification leads to a biphasic reaction medium, due to the formation of a second aqueous phase. A rigorous reactor model is proposed to calculate compositions over time, and to fit kinetic parameters, considering mass transfer and chemical reaction simultaneously. The biphasic model presented, which explicitly considers the presence of a second phase, is compared with the traditional monophasic approach that ignores the biphasic nature of reaction medium. The best-fitted monophasic model is not able to represent experimental data. On the other hand, the biphasic model allows to accurately fit experimental data, indicating the importance of modeling two-phase systems properly.
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Solvent-free Ethyl Oleate synthesis mediated by lipase from Candida antarctica B adsorbed on polypropylene powder
Catalysis Today, 2005Co-Authors: Maria Laura Foresti, Maria Lujan FerreiraAbstract:The enzymatic synthesis of Ethyl Oleate by direct esterification of oleic acid and ethanol in solvent-free media has been studied. Native lipase from Candida antarctica B and Candida antarctica B lipase adsorbed on powdered polypropylene were used with promising results. The influence of different parameters such us temperature, mass of lipase and aqueous content of reaction medium, on conversion profiles has been carefully studied. High water contents that ensured the co-existence of two liquid phases gave the best results, with conversions of up to 78.6% in 7 h of reaction. Pre-treatment with octane/buffer mixtures significantly reduced agglomeration of the immobilized catalyst, leading to important increments in specific enzymatic activity, when compared with non-pre-treated biocatalyst. Lipase desorption from PP has also been studied.
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effect of several reaction parameters in the solvent free Ethyl Oleate synthesis using candida rugosa lipase immobilised on polypropylene
Biochemical Engineering Journal, 2005Co-Authors: Maria Laura Foresti, A F Errazu, Maria Lujan FerreiraAbstract:Abstract Lipase from Candida rugosa was immobilised onto polypropylene powder by physical adsorption. The immobilised catalyst (CR/PP) was used in the enzymatic synthesis of Ethyl Oleate in solvent-free medium. The influence of the initial water content, acidity of the aqueous media added, mass of catalyst, reaction temperature, substrate ratio, etc., on enzymatic activity, has been studied. Comparison of specific enzymatic activities achieved using the prepared catalyst and the crude lipase demonstrated that C. rugosa lipase was interfacially activated upon its adsorption on polypropylene. Besides, immobilisation of the lipase led to enhanced thermal stability. Experimental data reported in this manuscript do not belong to equilibrium data but to enzymatic activity attained in the first 2 h of reaction. After this period, it was shown that, in the current synthesis, deactivation/agglomeration/inhibition of the catalyst prevented further CRL activity. However, 2 h measurements allowed fulfilling the aim of this work: the determination of the best conditions for Ethyl Oleate production in short periods of time, using an immobilised derivative of a relatively cheap lipase as it is C. rugosa lipase. Best results were achieved in the reaction performed at 45 °C and 350 rpm, with an initial stoichiometric ratio of substrates, 20% of aqueous content, and mediated by 50 mg of CR/PP (0.0585 mmol/mg of CR-h). The deleterious effect of ethanol excess and agglomeration of the native and immobilised catalyst have been analysed.
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interfacial activation and bioimprinting of candida rugosa lipase immobilized on polypropylene effect on the enzymatic activity in solvent free Ethyl Oleate synthesis
Enzyme and Microbial Technology, 2005Co-Authors: Maria Laura Foresti, Graciela Alimenti, Maria Lujan FerreiraAbstract:Abstract Lipase from Candida rugosa adsorbed on polypropylene powder (CR/PP) was subjected to activation pre-treatments in order to enhance its activity in solvent-free Ethyl Oleate synthesis. The lipase activation achieved upon adsorption onto a hydrophobic support like PP was further enhanced through oil–water interfacial activation and bioimprinting of the immobilized catalyst. Several aliphatic hydrocarbons/buffer pH 7 mixtures were used in the pre-activation of CR/PP with specific activity increments of up to 29%. Molecular bioimprinting was also performed, with specific activity enhancement of near 70% with respect to non-treated CR/PP. The effect of several fatty acids used as templates and the water present in the reaction medium was studied. The oil–water activation and bioimprinting treatments that led to the best activities were assayed at the immobilization step. Instead of pre-treating CR/PP adsorbed in buffer medium, interfacial activation with octane/buffer and bioimprinting with a mix of fatty acids were carried out in the immobilization vial . The best results were found for CR/PP immobilized in 5/95 octane/buffer (v/v, %) medium. In that way, a biocatalyst with enhanced specific activity is obtained right from the immobilization vial with no need of further activation steps prior to reaction.
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Ethyl Oleate synthesis using Candida rugosa lipase in a solvent-free system. Role of hydrophobic interactions.
Biomacromolecules, 2004Co-Authors: G. Trubiano, Daniel Oscar Borio, Maria Lujan FerreiraAbstract:The solvent-free esterification reaction of a commercial oleic acid and ethanol was selected as the test reaction for Candida rugosa lipase immobilized on polypropylene (PP) at 318 K (initial molar ratio 1:1). Adding of water from 0 to 30 wt. % (in gram per gram of fatty acid × 100) and the pretreatment of Candida rugosa lipase with polyEthylenglycol (PEG), octane, and acetone increases the conversion to Ethyl esters. The role of hydrophobic interactions of the lipase with PP and PEG was studied using molecular mechanics (MM2) for calculation of steric energies and the parametrized model (PM3) for calculation of enthalpy changes upon interaction. The nonpolar lateral groups of amino acids interact strongly with PP, whereas polar groups interact more strongly with PEG. Both interactions stabilize the open, active conformation of the lipase from Candida rugosa. Activities ranged from 5 × 10-5 to 2.0 × 10-4 mol Ethyl Oleate/h/mg enzyme, depending on reaction conditions. Steric energy changes vary between +30...
Mirjana Lj Kijevcanin - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic and transport properties of ternary mixture Ethyl Oleate n hexadecane 1 butanol and its binary constituents Ethyl Oleate 1 butanol and Ethyl Oleate n hexadecane at different temperatures and atmospheric pressure
Journal of Molecular Liquids, 2020Co-Authors: Mohamed A Aissa, Ivona R Radovic, Zoran Simic, Mirjana Lj KijevcaninAbstract:Abstract Densities, viscosities, speeds of sound and refractive indices have been measured for the ternary system Ethyl Oleate + n-hexadecane +1-butanol, and for the corresponding binaries Ethyl Oleate +1-butanol and Ethyl Oleate + n-hexadecane, in the temperature range from T = (293.15 to 343.15) K and at atmospheric pressure. Experimental data were employed to calculate some derived thermodynamic parameters, i.e. excess molar volumes (VE), viscosity deviations (Δη) and deviations in refractive index (ΔnD). Additionally, molar excess Gibbs free energies of activation of viscous flow (ΔG⁎E) and deviations in isentropic compressibility (Δκs) were calculated. A graphical representation of excess molar volumes and refractive indices show positive deviation from ideal behavior for both binary systems whereas deviation in viscosity shows negative nature for the Ethyl Oleate + n-hexadecane system and an inversion sign for Ethyl Oleate +1-butanol binary system. A negative deviation in isentropic compressibility was confirmed for the systems Ethyl Oleate +1-butanol while positive deviation was observed in Ethyl Oleate + n-hexadecane system. It can be concluded that dispersive forces predominate between the components in binary systems and the observed behavior seems to suggest that the properties obtained for the ternary mixture are dominated by the binary effects. The viscosities of the binary systems were modeled by UNIFAC-VISCO, ASOG-VISCO, Teja-Rice and McAllister models. The results showed that McAllister's multibody model is suitable to describe viscosities for binary systems with maximum percentage deviations less than 0.5%.
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a systematic study on volumetric and transport properties of binary systems 1 propanol n hexadecane 1 butanol n hexadecane and 1 propanol Ethyl Oleate at different temperatures experimental and modeling
Fluid Phase Equilibria, 2018Co-Authors: Mohamed A Aissa, Ivona R Radovic, Mirjana Lj KijevcaninAbstract:Abstract Densities (ρ), viscosities (η), speed of sounds (u) and refractive indices (nD) at temperature range (293.15–343.15) K with 5 K interval, for three binary mixtures (1-propanol + n-hexadecane, 1-butanol + n-hexadecane and 1-propanol + Ethyl Oleate), were measured at atmospheric pressure. Based on the corresponding experimental data, excess molar volume (VE), viscosity deviation (Δη) and deviation in refractive index (ΔnD) have been calculated. Beside these properties, molar excess Gibbs free energies of activation of viscous flow (Δ*GE) and deviation in isentropic compressibility ( Δ κ s ) were calculated from measured density, viscosity and speed of sound data. The excess/deviation functions have been fitted by Redlich-Kister equation and discussed in terms of molecular interactions existing in the mixtures. Viscosity modeling was performed using four models: UNIFAC-VISCO, ASOG-VISCO, Teja-Rice and McAllister. Experimental viscosity data have been used to determine new binary UNIFAC-VISCO and ASOG-VISCO interaction parameters and the interaction parameters for correlation models by applying some optimization technique. For all systems, positive deviations were observed for the excess molar volumes in the whole concentration range. A negative deviation and an inversion sign for the excess dynamic viscosity were observed in the systems of 1-butanol + n-hexadecane and 1-propanol + n-hexadecane, respectively, while positive deviation was observed for 1-propanol + Ethyl Oleate mixture. The results of viscosity modeling showed that four-body McAllister models are suitable to describe viscosities for all systems and temperatures with maximum percentage deviations (PDmax) less than 0.5%.
Maria Laura Foresti - One of the best experts on this subject based on the ideXlab platform.
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kinetic modeling of enzymatic Ethyl Oleate synthesis carried out in biphasic systems
Applied Catalysis A-general, 2008Co-Authors: Maria Laura Foresti, Maria Lujan Ferreira, M Pedernera, Veronica BucalaAbstract:This work presents a new approach for the kinetic modeling of solvent free Ethyl Oleate synthesis, catalyzed by an enzymatic catalyst. The biocatalyst used was the lipase from Candida antarctica B immobilized onto chitosan powder. Thermodynamic calculations revealed that the addition of water to hydrate the biocatalyst, or the production of water during esterification leads to a biphasic reaction medium, due to the formation of a second aqueous phase. A rigorous reactor model is proposed to calculate compositions over time, and to fit kinetic parameters, considering mass transfer and chemical reaction simultaneously. The biphasic model presented, which explicitly considers the presence of a second phase, is compared with the traditional monophasic approach that ignores the biphasic nature of reaction medium. The best-fitted monophasic model is not able to represent experimental data. On the other hand, the biphasic model allows to accurately fit experimental data, indicating the importance of modeling two-phase systems properly.
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Solvent-free Ethyl Oleate synthesis mediated by lipase from Candida antarctica B adsorbed on polypropylene powder
Catalysis Today, 2005Co-Authors: Maria Laura Foresti, Maria Lujan FerreiraAbstract:The enzymatic synthesis of Ethyl Oleate by direct esterification of oleic acid and ethanol in solvent-free media has been studied. Native lipase from Candida antarctica B and Candida antarctica B lipase adsorbed on powdered polypropylene were used with promising results. The influence of different parameters such us temperature, mass of lipase and aqueous content of reaction medium, on conversion profiles has been carefully studied. High water contents that ensured the co-existence of two liquid phases gave the best results, with conversions of up to 78.6% in 7 h of reaction. Pre-treatment with octane/buffer mixtures significantly reduced agglomeration of the immobilized catalyst, leading to important increments in specific enzymatic activity, when compared with non-pre-treated biocatalyst. Lipase desorption from PP has also been studied.
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effect of several reaction parameters in the solvent free Ethyl Oleate synthesis using candida rugosa lipase immobilised on polypropylene
Biochemical Engineering Journal, 2005Co-Authors: Maria Laura Foresti, A F Errazu, Maria Lujan FerreiraAbstract:Abstract Lipase from Candida rugosa was immobilised onto polypropylene powder by physical adsorption. The immobilised catalyst (CR/PP) was used in the enzymatic synthesis of Ethyl Oleate in solvent-free medium. The influence of the initial water content, acidity of the aqueous media added, mass of catalyst, reaction temperature, substrate ratio, etc., on enzymatic activity, has been studied. Comparison of specific enzymatic activities achieved using the prepared catalyst and the crude lipase demonstrated that C. rugosa lipase was interfacially activated upon its adsorption on polypropylene. Besides, immobilisation of the lipase led to enhanced thermal stability. Experimental data reported in this manuscript do not belong to equilibrium data but to enzymatic activity attained in the first 2 h of reaction. After this period, it was shown that, in the current synthesis, deactivation/agglomeration/inhibition of the catalyst prevented further CRL activity. However, 2 h measurements allowed fulfilling the aim of this work: the determination of the best conditions for Ethyl Oleate production in short periods of time, using an immobilised derivative of a relatively cheap lipase as it is C. rugosa lipase. Best results were achieved in the reaction performed at 45 °C and 350 rpm, with an initial stoichiometric ratio of substrates, 20% of aqueous content, and mediated by 50 mg of CR/PP (0.0585 mmol/mg of CR-h). The deleterious effect of ethanol excess and agglomeration of the native and immobilised catalyst have been analysed.
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interfacial activation and bioimprinting of candida rugosa lipase immobilized on polypropylene effect on the enzymatic activity in solvent free Ethyl Oleate synthesis
Enzyme and Microbial Technology, 2005Co-Authors: Maria Laura Foresti, Graciela Alimenti, Maria Lujan FerreiraAbstract:Abstract Lipase from Candida rugosa adsorbed on polypropylene powder (CR/PP) was subjected to activation pre-treatments in order to enhance its activity in solvent-free Ethyl Oleate synthesis. The lipase activation achieved upon adsorption onto a hydrophobic support like PP was further enhanced through oil–water interfacial activation and bioimprinting of the immobilized catalyst. Several aliphatic hydrocarbons/buffer pH 7 mixtures were used in the pre-activation of CR/PP with specific activity increments of up to 29%. Molecular bioimprinting was also performed, with specific activity enhancement of near 70% with respect to non-treated CR/PP. The effect of several fatty acids used as templates and the water present in the reaction medium was studied. The oil–water activation and bioimprinting treatments that led to the best activities were assayed at the immobilization step. Instead of pre-treating CR/PP adsorbed in buffer medium, interfacial activation with octane/buffer and bioimprinting with a mix of fatty acids were carried out in the immobilization vial . The best results were found for CR/PP immobilized in 5/95 octane/buffer (v/v, %) medium. In that way, a biocatalyst with enhanced specific activity is obtained right from the immobilization vial with no need of further activation steps prior to reaction.