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Vacek, Miroslav; Zarevúcká, Marie; Wimmer, Zdeněk; Stránský, Karel; Demnerova, Kateřina; Legoy, Marie‐Dominique

doi:10.1023/a:1005637018167

Cited by 23 publications

(3 citation statements)

References 13 publications

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“…Acceleration or changes in reactivity and selectivity could be explained by a specific radiation effect and not merely by a thermal effect. However, in some enzymatic reactions, in which reaction rate, yield and selectivity such as stereo-selectivity or region-selectivity are obviously influenced (Lin and Lin, 1998;Parker et al, 1996;Ipsita and Gupta, 2003;Fang et al, 2003;Vacek et al, 2000;Yadav and Lathi, 2004).…”

Section: Selectivity Of Microwave Methodmentioning

confidence: 99%

Heat-Modeling of Microwave Assisted Epoxidation of Palm Acid Oil

Saifuddin¹

2011

American Journal of Applied Sciences

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Problem statement: While microwave chemistry could well be the most convenient, rapid and energy-saving way to initiate a chemical reaction, the issues of thermal versus microwave specific effect remain unaddressed. Approach: A three-dimensional Finite Element Model (FEM) was developed to predict temperature profile during the enzymatic epoxidation of palm acid oil using microwave heating. Three-dimensional partial differential equations are formulated for the electromagnetic field and heat and mass transfer processes. The temperature profile of the FEM generated from the commercial software (ANSYS Emag) was verified using experimental data from microwave oven heated samples containing palm acid oil and reactants in cylindrical bottles and has compared favorably with real time data. An Infra Red thermometer was used to measure temperature of the reactants during the real time experiment to ensure less contact with the reaction vessel. Results: Apart from ascertaining the temperature profile of the epoxidation process in the cylindrical bottle, the heat-modeling of this reaction can predict the Energy required during the reaction and provide insights to non-thermal microwave effects. It has shown the possibility of Microwave Non-Thermal Effects and Microwave Selectivity in Substrate Specificity. The energy used by the microwave irradiated reaction is by far much lesser than the energy used in conventional heating. This study has also improved the epoxidation process of Palm Acid Oil by incorporating enzyme as a catalyst and using microwave heating. Epoxidation can be done rapidly and at a lower level of activation energy of 27.767 kJ mol⁻¹. It is a green process with increased efficiency as it reduced a typically 5-hour reaction to less than an hour. Conclusion: In this study, a quantitative view of a microwave assisted process of enzymatic epoxidation has been established. We have successfully developed and experimentally validated a 3D electromagnetic heat transfer model. This model can thus be used to predict the energy of the epoxidation and other future microwave reactions. the study also have shown the existence of microwave non-thermal effects and microwave selectivity in substrate specificity

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Section: Selectivity Of Microwave Methodmentioning

confidence: 99%

Heat-Modeling of Microwave Assisted Epoxidation of Palm Acid Oil

Saifuddin¹

2011

American Journal of Applied Sciences

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“…To assess its synthetic activity in esterification reactions, ASL was tested as catalyst of the direct esterification of three different carboxylic acids using a procedure adapted from Vacek et al 40 The carboxylic acids assayed were butyric, caproic and lauric acids, and the alcohol used in all cases was n-butanol. The reaction was performed in organic solvent medium.…”

Section: Determination Of Synthetic Activity Of Aslmentioning

confidence: 99%

Biocatalytic characterization of a naturally immobilized lipase found in Araujia sericifera Brot. (Apocynaceae) latex

Meztler¹,

Fait²,

Foresti

et al. 2014

Catal. Sci. Technol.

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Lipase activity found in the insoluble fraction of Araujia sericifera Brot. (Apocynaceae) (ASL) latex, a native South American milkweed, was characterized by use of different test reactions and under different reaction conditions. In this context, hydrolytic lipase activity towards both natural and synthetic substrates and towards fatty acid esterifications was assayed at different temperatures, pH values, and biocatalyst loads. In the case of natural substrates (cottonseed oil), highest lipase activity was found at pH 8.5 and 60°C. In the hydrolysis of synthetic substrates (p-nitrophenyl esters) the lipase showed preference for the lowest molecular-weight p-nitrophenyl ester assayed (butyrate). Results of the direct esterification of fatty acids of different chain length in organic media showed that esterification levels of up to 45% could be obtained in one hour of reaction. Activity results were compared with the activity shown by the commercial immobilized lipase Novozym 435 under defined reaction conditions. The high activity exhibited by ASL in the hydrolysis of natural substrates and particularly in the direct esterification of different fatty acids in organic medium, together with its high storage stability, suggests that this plant lipase is a promising biocatalyst for various biotechnological applications.

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“…9-13 Also, enzymatic stability is reportedly higher under microwave heating than under conventional thermal heating. 14 Very recently, a paper by some of the authors of these previous reports 10, 12 was published. It suggests that identical initial rate and conversion yield were obtained under microwave and conventional heating for the transesterification reaction between ethyl butyrate and butanol in a solvent-free system but that the kinetics of inactivation of the lipase are influenced differently depending on the heating method used.…”

Section: Introductionmentioning

confidence: 99%