Laccase immobilisation on mesostructured silicas

Extracellular laccase produced by the wood-rotting fungus Cerrena unicolor was immobilised covalently on the mesostructured siliceous foam (MCF) and three hexagonally ordered mesoporous silicas (SBA-15) with different pore sizes. The enzyme was attached covalently via glutaraldehyde (GLA) or by simple adsorption and additionally crosslinked with GLA. The experiments indicated that laccase bound by covalent attachment remains very active and stable. The best biocatalysts were MCF and SBA-15 with Si–F moieties on their surface. Thermal inactivation of immobilised and native laccase at 80°[degrees]C showed a biphasic-type activity decay, that could be modelled with 3parameter isoenzyme model. It appeared that immobilisation did not significantly change the mechanism of activity loss but stabilised a fraction of a stable isoform. Examination of time needed for 90% initial activity loss revealed that immobilisation prolonged that time from 8 min (native enzyme) up to 155 min (SBA-15SF)

Stimuli-Responsive PNIPAM Based Copolymers: Modeling and Light Scattering Investigations

Temperature dependent behavior of poly(N-isopropylacrylamide) (PNIPAM) copolymers was investigated in three buffer-stabilized environments. The tests were performed in thermostabilized goniometer by dynamic and static light scattering. From the dynamic light scattering hydrodynamic radius was obtained. Based on the static light scattering data, calculations of the particle radius from the form factor model were done. Depending of the kind of copolymer, the different material response to temperature was observed. Also the characterization of dry particles was done by scanning electron microscope. These scanning electron microscopy micrograms showed the possibility of particles to aggregation

Kinetics of Enantiomerically Enriched Synthesis of Solketal Esters Using Native and SBA-15 supported P. Fluorescens Lipase

The studies showed that alkaline lipase from Pseudomonas fluorescens enables an irreversible transesterification of vinyl esters to give enantiomeric excess (eeR) of about 80% using vinyl butyrate as acyl donor and diisopropyl ether as a solvent, at partially optimized conditions. For the native lipase the process was adequately described by a five-parameter Ping-Pong Bi Bi model for both enantiomers plus expression accounting for the formation of enzyme-acyl donor complex, but for the same lipase supported on mesoporous materials of SBA-15-Oc type, R-product inhibition also had to be taken into account. The use of hydrophobic support increased by more than two-fold the rate of the S-solketal conversion but even more that of R-solketal. Thus the immobilization of lipase had very positive effect on the process kinetics but decreased its enantioselectivity

Kinetyka reakcji estryfikacji kwasu octowego metanolemwobecności katalizatora mcf funkcjonalizowanego grupami kwasowymi

The esterification of acetic acid with methanol was studied in the presence of heterogeneous acidic catalyst - sulfonic acid functionalized silica mesoporous cellular foam (MCF) in order to determine its potentials. The effects of catalyst loading, molar ratio of substrates and temperature on the reaction rate were discussed. The kinetic model for this reaction was proposed.Przedstawiono wyniki badań kinetycznych reakcji estryfikacji kwasu octowego metanolem w obecności stałego kwasowego katalizatora – mezoporowatowego materiału krzemionkowego o strukturze piankowej, funkcjonalizowanego grupami sulfonowymi. Określono wpływ ilości katalizatora, stosunku molowego substratów oraz temperatury na szybkość reakcji. Zaproponowano model kinetyczny reakcji przeprowadzonej w obecności otrzymanego katalizatora

Review on hierarchically microstructured monolithic reactors for high yield continuous production of fine chemicals

Preparation and properties of hierarchically structured porous silica monoliths have been discussed from the viewpoint of their application as continuous microreactors for liquid-phase synthesis of fine chemical in multi kilogram scales. The results of recent topical papers published by two research teams of Institute of Chemical Engineering Polish Academy of Sciences (ICE) and Department of Chemical Engineering and Process Design, Chemical Faculty, Silesian University of Technology (SUT) have been analyzed to specify the governing traits of microreactors. It was concluded that even enhancement factor of 100 in activity, seen in enzyme catalyzed reactions, can be explained by a proportional reduction of its physical constraints, i.e. huge enhancement of external mass transfer and micromixing. It is induced by very chaotic flows of liquid in tens of thousands of waving connected channels of ca. 25–50 mm in diameter, present in the skeleton. The scale of enhancement in the caseof less active catalysts was smaller, but still large enough to consider the most practical applications