engleski

Analysis of effective diffusivities of molecules in microreactor

Microreactors are defined as miniaturised reaction system, fabricated by microtechnology and precision engineering. They enable chemical and biochemical processes to be conducted in a continuous way instead of batch processing. Miniaturization has a number of advantages comparing to classical macroreactors ; improved control of reaction parameters, smaller amounts of by-products and higher selectivity, higher yields… [1]. Laminar flow (low Reynolds numbers) dominates in microreactors comparing to tubular macroreactor. With well-defined flowlines, mass transfer for laminar flow in microreactor takes place only by diffusion. Due to the small dimensions of microchanells diffusion times (time taken by molecule to travel distance of microchanel half-width by diffusive process) are very short [2]. In this work effective diffusivities of two “small molecules” (glucose and catechol) and two proteins (glucose oxidase and laccase) were analysed. Experiments were performed in microreactor with internal volume of 6 µL equipped with two “Y” shaped inflows and outflows without specific surface roughness in laminar flow profile. Effective diffusion coefficients for all investigated molecules were calculated using different empirical correlations (Wilke-Change, Scheibel, Reddy-Doraiswamy, Young, He and Niemeyer and Tyn and Gusek) and included into mathematical model for diffusion in microreactor. Mathematical model was solved using numerical approximation where microreactor was described by two parallel ideal tubular reactors. Experimental results for concentration of all investigated molecules for both outflows of microreactor were compared with simulation results.

effective diffusivities; correlation models; microreactor

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