Silica aerogels as supports for lipase catalyzed esterifications at sub- and supercritical conditions

Novak, Zoran; Habulin, Maja; Krmelj, V.; Knez, Željko

doi:10.1016/s0896-8446(02)00233-4

Cited by 66 publications

(21 citation statements)

References 13 publications

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“…These experiments were undertaken in such conditions that longitudinal relaxation (T 1 ) could be considered as quite complete, that allows spectra deconvolution using DmFit modelling software (http://crmhteurope.cnrs-orleans.fr) in order to get quantitative data about siliceous network. 13 C CP-MAS Solid-State NMR experiments were performed on an Avance III 500 Bruker spectrometer (11.73 Tesla) except for the hybrid xerogel which was analysed with an Avance III 400 Bruker spectrometer. The spectrometers were equipped with a Bruker 4BL CP/MAS 1 H/BB probe and the samples were span at 14 kHz.…”

Section: Characterizationmentioning

confidence: 99%

“…This technique largely attenuates the capillary stresses responsible for the gel network compression, its shrinkage and its porosity loss [12]. It was shown that extremely high porous silica aerogels could be obtained with high specific surface areas (500-1,000 m 2 /g), low bulk densities (0.003-0.35 g/cm 3 ), low thermal conductivities (0.014 W/m K), and refractive indices between 1.008 and 1.4 [13]. Aerogels became an important research area for a wide range of scientific and technological applications, for instance, thermal and acoustic insulation [14,15], Cerenkov radiation detectors [16], photoluminescent and radioluminescent devices [17][18][19], comet dust and aerosol particles collectors [20,21], adsorbents [22], catalysts [23] and catalyst supports [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Mesoporous Hybrid Silica-Polyacrylamide Aerogels and Xerogels

Ramadan

Coradin

Masse

et al. 2010

Silicon

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We report the synthesis of highly porous hybrid silica-polyacrylamide aerogels where the inorganic network was obtained through the hydrolysis and poly-condensation of tetramethoxysilane via a two-step sol-gel process while the polyacrylamide polymer was made by photocopolymerization of two organic monomers, the acrylamide and the bis-acrylamide. These aerogels were obtained after a carbon dioxide supercritical drying while the corresponding xerogels were dried by simple evaporation. These materials, as well as pure silica and polyacrylamide aerogels and xerogels, were characterized by FTIR spectroscopy, solid-state 29 Si and 13 C NMR spectroscopy, Thermogravimetric Analysis, a nitrogen adsorptiondesorption technique, and Scanning Electron Microscopy. The FTIR and NMR spectra and the TGA/DTA analyses confirm the coexistence of highly branched silica and polyacrylamide networks reflecting the hybrid nature of the materials obtained. Nitrogen adsorption measurements reveal high specific surface areas and pore size distributions disclosing the mesoporous character of these hybrid materials. Hybrid silica-polyacrylamide aerogels having a specific surface area equal to 572 m 2 /g and a pore volume 1.92 cm 3 /g were successfully prepared for the first time in this study. The high porosity of these aerogels is due to a better resistance of the silica network to capillary forces during the supercritical drying when silica coexists with a polyacrylamide network.

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Section: Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Mesoporous Hybrid Silica-Polyacrylamide Aerogels and Xerogels

Ramadan

Coradin

Masse

et al. 2010

Silicon

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“…Studies have shown the use of aerogels for lipase encapsulation by the sol-gel technique, as the enzyme is physically encapsulated in a rigid glass framework that permits stabilisation of the enzymes and gives a tertiary structure because of the tight gel network. [3][4][5] There are various methods for enzyme immobilization which may be physical or chemical. Among them are physical adsorption, covalent binding, crosslinking, encapsulation, and others.…”

Section: Introductionmentioning

confidence: 99%

The Novel Mesoporous Silica Aerogel Modified With Protic Ionic Liquid for Lipase Immobilization

Barbosa¹,

Lisboa²,

Silva³

et al. 2016

Química Nova

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Recebido em 24/08/2015; aceito em 22/12/2015; publicado na web em 11/02/2016Mesoporous silica supports (aerogels) were used to immobilize Burkholderia cepacia lipase (BC) by encapsulation (EN or ENIL), physical adsorption (ADS or ADSIL) and covalent binding (CB or CBIL) into or onto the aerogel modified with protic ionic liquid (PIL). Yield immobilization (Ya) and operational stability were determined by the hydrolytic reaction of olive oil. Ya (37% to 83% by physical adsorption) and operational stability (2 to 23 batches by encapsulation) increased when the support was modified with PIL. For immobilized derivates observed by the BET method, in this case ADS and CB for ADSIL and CBIL, increased pores size was observed, possibly due to the higher amount of BC immobilized conferring Ya and operational stability. This effect was probably attributed to the entry of the enzyme into the pores of the silica aerogel structure. SEM images showed a change in the structure and properties of immobilized lipase derived with PIL. A characteristic FTIR band was obtained for the silanol groups and amides I, IV and V, demonstrating the efficiency of immobilization of BC. The most efficient biocatalysts were ADSIL with regard to yield immobilization and ENIL for operational stability.

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“…Moreover, for catalysis of chemical reaction in organic solvent, adsorption on silica is the simplest, inexpensive and trouble-free immobilization technique because enzymes are normally not soluble in organic media [12,13]. It is also advantageous to use a porous support so that the enzyme is spread on a large surface area [14,15]. So in the present study we have used the silica gel, a robust and easily available matrix for immobilization of lipase [16].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of thermostabilty and ester synthesis ability of free and immobilized lipases on cross linked silica gel

Kumari

Mahapatra

Garlapati

et al. 2007

Bioprocess Biosyst Eng

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A novel support has been utilized for immobilization of lipase, which was prepared by amination of silica with ethanolamine followed by cross linking with glutaraldehyde. Lipases from Rhizopus oryzae 3562 and Enterobacter aerogenes were immobilized on activated silica gel, where they retained 60 and 50% of respective original activity. The thermal stability of the immobilized lipases was significantly improved in comparison to the free forms while the pH stability remained unchanged. E. aerogenes and R. oryzae 3562 lipases retained 75 and 97% of respective initial activity on incubation at 90 degrees C, whereas both the free forms became inactive at this temperature. The conversion yield of isoamyl acetate was found to be higher with the immobilized fungal (90 vs. 21%) and bacterial lipases (64 vs. 18%) than the respective free forms. Immobilized R. oryzae 3562 lipases retained 50% activity for isoamyl acetate synthesis up to ten cycles whereas it was eight cycles for E. aerogenes.

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Silica aerogels as supports for lipase catalyzed esterifications at sub- and supercritical conditions

Cited by 66 publications

References 13 publications

Synthesis and Characterization of Mesoporous Hybrid Silica-Polyacrylamide Aerogels and Xerogels

Synthesis and Characterization of Mesoporous Hybrid Silica-Polyacrylamide Aerogels and Xerogels

The Novel Mesoporous Silica Aerogel Modified With Protic Ionic Liquid for Lipase Immobilization

Comparative study of thermostabilty and ester synthesis ability of free and immobilized lipases on cross linked silica gel

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