Diffusion of silver ions in zeolite Y preceded by a coupled chemical reaction: Electrochemical observation and modelling

It is the goal of this work to show that the complex chronoamperometry of partially silver ion exchanged Ag3.1Na52.9Y can be understood by treating the passage of silver cations to the electrode solution interface as a diffusion-controlled reaction preceded by a feeding chemical step. This is achieved via the solution of a CE (chemical followed by electrochemical) process using simulation methods adopting a finite difference approach whereupon the zeolite is divided into a set of discrete volume elements corresponding to the large and small channels of zeolite Y. The fit with the experimentally recorded chronoamperometry of a monograin Ag3.1Na52.9Y-modified electrode covers 30 s after the application of the pulse. Using this approach, accurate determinations of intrazeolite diffusion coefficients will be possible only when exact equilibrium cation locations are known.