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Mathematical modelling of the diffusion profiles of Briggs-Rauscher reaction components in a microreactor

Effective diffusivity presents an important physical-chemical property of the molecule and it is extremely important for design and optimization of the process in which it is included. Effective diffusivity coefficient presents the diffusivity capacity of the molecule and molecules with higher values of the effective diffusivity coefficient move faster. Due to the small dimensions of the microchannels, microreactors ensure ideal conditions for diffusion phenomena analysis in defined and controlled conditions. Reactor dimensions reduction to micro scale has significant effect on the diffusion time. Diffusion time is defined as the ratio of the square of the path that molecule has to pass in a microchannel and the diffusion coefficient. Due to the small dimension of the microchannels, molecules diffuse very fast in the process space and in the laminar flow rate diffusion profile depends only on the residence time. In this work 2D mathematical model was used to analyse the diffusion profiles of the Briggs-Rauscher (BR) oscillatory reaction components in a microreactor. Mathematical model includes convection in the flow direction and diffusion in two directions. Mathematical model simulations were performed using WR Mathematica 10.0 applying the finite difference method for solving the partial differential equation using the effective diffusivity coefficients data from the literature. The simulations were performed for all six components (hydrogen peroxide, sulfuric acid, potassium iodate, malonic acid, manganese sulphate, starch) of the BR reaction. The obtained diffusivity profiles will be used in the optimization of the BR reaction in the continuous mode at the macro scale.

microreactors; effective diffusivity; Briggs-Rauscher reaction

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