Magnetically modified palygorskite composites were synthesized with γ-Fe2O3 dispersing on the external surface of clay mineral. The magnetic clay was characterized with Fourier transform infrared, X-ray diffraction, ...Magnetically modified palygorskite composites were synthesized with γ-Fe2O3 dispersing on the external surface of clay mineral. The magnetic clay was characterized with Fourier transform infrared, X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. Candida sp. 99–125 lipase was immobilized on magnetic palygorskite composites by physical adsorption with enzyme loading of41.5 mg·g-1support and enzyme activity of 2631.6 U·(g support)-1. The immobilized lipase exhibit better thermal and broader p H stability and excellent reusability compared with free lipase.展开更多
The effect of low energy ultrasound in biochemistry and biotechnology has attracted great attention in recent years.It can enhance substrate dissolution and improve mass transfer within and outside of a cell,both of w...The effect of low energy ultrasound in biochemistry and biotechnology has attracted great attention in recent years.It can enhance substrate dissolution and improve mass transfer within and outside of a cell,both of which are beneficial to the synthesis of fructose ester.Here we describe the experimental study of the effect of ultrasounds of different intensity on the lipase-catalyzed synthesis of fructose ester in the solvent butanone.The results were compared with control reactions performed with no ultrasound.High performance liquid chromatography(HPLC)and thin layer chromatography(TLC)were used for qualitative and quantitative analyses.The results show the following:1)the concentration of monoester and diester increased with the reaction time,either with or without ultrasonic irradiation.Low energy ultrasound accelerated the reaction due to the effect of ultrasonic steady cavitations,and high energy ultrasound was not beneficial to the reaction.2)The application of ultrasound played an important role in our lipase-catalyzed reaction.It decreased reaction time as compared to a reaction without ultrasound that resulted in the same yield,increased reaction rate,and enhanced the amount of fructose ester produced.When the frequency was 10 kHz and sound intensity was 0.16W·m^(-2),the concentration of ester was twofold more than without ultrasonic irradiation after a reaction time of up to 12 h.With the proper ultrasonic parameters,the overall concentration of production appeared to increase exponentially with the reaction time.3)Ultrasound had little effect on the initial reaction rate,and continuous ultrasonic irradiation was favorable for the reaction.The longer the reaction continued,the more obvious the effects of the ultrasound became in our experiments.展开更多
基金the National Basic Research Program of China(2009CB724700)the Foundation of Jiangsu Province of China for College Postgraduate Students in Innovation Engineering(CXZZ12_0440)
文摘Magnetically modified palygorskite composites were synthesized with γ-Fe2O3 dispersing on the external surface of clay mineral. The magnetic clay was characterized with Fourier transform infrared, X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. Candida sp. 99–125 lipase was immobilized on magnetic palygorskite composites by physical adsorption with enzyme loading of41.5 mg·g-1support and enzyme activity of 2631.6 U·(g support)-1. The immobilized lipase exhibit better thermal and broader p H stability and excellent reusability compared with free lipase.
基金the financial support of the Innovation Fund for Doctoral Theses and the Nanjing University of Technology(No.BSCX200811)the Fundation of the Nanjing University of Technology(No.39708006).
文摘The effect of low energy ultrasound in biochemistry and biotechnology has attracted great attention in recent years.It can enhance substrate dissolution and improve mass transfer within and outside of a cell,both of which are beneficial to the synthesis of fructose ester.Here we describe the experimental study of the effect of ultrasounds of different intensity on the lipase-catalyzed synthesis of fructose ester in the solvent butanone.The results were compared with control reactions performed with no ultrasound.High performance liquid chromatography(HPLC)and thin layer chromatography(TLC)were used for qualitative and quantitative analyses.The results show the following:1)the concentration of monoester and diester increased with the reaction time,either with or without ultrasonic irradiation.Low energy ultrasound accelerated the reaction due to the effect of ultrasonic steady cavitations,and high energy ultrasound was not beneficial to the reaction.2)The application of ultrasound played an important role in our lipase-catalyzed reaction.It decreased reaction time as compared to a reaction without ultrasound that resulted in the same yield,increased reaction rate,and enhanced the amount of fructose ester produced.When the frequency was 10 kHz and sound intensity was 0.16W·m^(-2),the concentration of ester was twofold more than without ultrasonic irradiation after a reaction time of up to 12 h.With the proper ultrasonic parameters,the overall concentration of production appeared to increase exponentially with the reaction time.3)Ultrasound had little effect on the initial reaction rate,and continuous ultrasonic irradiation was favorable for the reaction.The longer the reaction continued,the more obvious the effects of the ultrasound became in our experiments.
