Estudo da difusão anômala na resposta elétrica de uma célula eletrolítica : circuitos equivalentes e elementos de fase constante

Abstract

A connection between the impedance spectroscopy response of an anomalous Poisson-Nernst-Planck (PNPA) diffusional model and of equivalent circuits containing constant phase elements (CPEs) is established for a typical electrolytic cell. In the presence of an electrical current, this device directs a nonspontaneous reaction (electrolysis) to promote the ionic conduction through the cell, with considerable industrial importance as the aluminum production. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPEs in the circuit. It shows that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained using integro-differential boundary conditions to describe anomalous diffusive process. The electrical response of an electrolytic cell in which the diffusion of mobile ions in the bulk is governed by a fractional diffusion equation of distributed order is analyzed, besides the theory and fundamentals concepts of impedance spectroscopy and theusual Poisson-Nernst-Planck (PNP) diffusional model