Scaling anomalies in reaction front dynamics of confined systems

We review recent developments in the study of the diffusion reaction system of the type A+B→C in which the reactants are initially separated. We consider the case where the A and B particles are initially placed uniformly in Euclidean space at x>0 and x<0 respectively. We find that whereas for d≥2 a single scaling exponent characterizes the width of the reaction zone, a multiscaling approach is needed to describe the one-dimensional system. We also present analytical and numerical results for the reaction rate on fractals and percolation systems.

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Study of an A+2B--->C Reaction-Diffusion System with Initially Separated Components

MRS Proceedings ◽

10.1557/proc-366-319 ◽

1994 ◽

Vol 366 ◽

Author(s):

Andrew Yen ◽

Raoul Kopelman

Keyword(s):

Reaction Front ◽

Reaction Rate ◽

Reaction Diffusion ◽

Biological Processes ◽

Local Production ◽

Kinetic Behavior ◽

Acetate Trihydrate ◽

Physical Chemical ◽

Global Reaction ◽

Front Dynamics

ABSTRACTThe presence of a reaction front is a characteristic feature of a variety of physical, chemical and biological processes. A chemical reaction exhibits a front (spatially localized region where concentration of product is non zero), provided the diffusing reactants are separated in space. We study the reaction front dynamics of a termolecular A+2B--->C reaction with initially separated components in a capillary. The reaction tetra+2Ni2+--->1:2 complex is used, where ‘tetra’ is disodium ethyl bis(5-tetrazolylazo) acetate trihydrate. We measure and compare with theory the dynamic quantities that characterize the kinetic behavior of the system: the global reaction rate R(t), the location of the reaction center xf(t), the front's width w(t), and the local production rate R(xf,t). The non-classical nature of this dynamical system is confirmed.

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Experimental Study of An A+B→C Reaction-Diffusion System in a Capillary: Crossovers from Reaction to Diffusion-Limited Regimes

MRS Proceedings ◽

10.1557/proc-290-273 ◽

1992 ◽

Vol 290 ◽

Cited By ~ 4

Author(s):

Yong-Eun Koo ◽

Raoul Kopelman ◽

Andrew Yen ◽

Anna Lin

Keyword(s):

Experimental Study ◽

Reaction Zone ◽

Reaction Front ◽

Reaction Rate ◽

Local Reaction ◽

Reaction Diffusion ◽

Theoretical Studies ◽

Boundary Motion ◽

Diffusion Limited ◽

Front Dynamics

AbstractContinuing work on elementary A+B→C reactions in capillaries, we study the reaction front dynamics of xylanol orange with Cr3+ in an effectively one-dimentional system with initially separated reactants. This reaction, in contrast to previously studied systems, is not strictly in the diffusion limited regime. i.e. the probability of reaction between species is not unity. Anamalous behavior not seen in the diffusion-limited case has been observed experimentally for the reaction rate, boundary motion, reaction zone width, and local reaction rate. The observed behavior is consistent with recent theoretical studies.

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