Fundamental aspects of fluidised bed electrodes

Kelsall, Geoffrey Howard (1975) Fundamental aspects of fluidised bed electrodes. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Following a review of the literature relating to the use of fluidised, beds in electrochemistry, a parametric study of a copper particle fluidised bed electrode (FBE) for copper electro winning from dilute solutions, is described. The results were treated by regression analysis, to yield a design equation which related a predicted current density to a function of the experimental variables. A feasibility study is then described, of the possible use of a lead particle FBE, for the treatment of chlor-alkali plant effluents containing low concentrations of mercuric chloride. This system was shown to be capable of operating at close to 1002 current efficiency. The diffusion controlled current density for the trapping of the mercury species as a lead amalgam, was more 'than two orders of magnitude greater than that predicted by the classical Nernst limiting current density equation, for the range of Hg(II) concentrations used. For design and 'scale-up purposes, a technique was developed to monitor the local behaviour of the FBE. This was intended to yield data complementary to the information obtained from the phenomenological approach of the parametric study. Using a suitable probe electrode, local potential fluctuations were monitored and analysed by an on-line, real-time, digital computer. This was capable of generating statistical information in the amplitude domain (probability density function), time domain, (autocorrelation function), and frequency domain (power spectral density function). A mathematical model was developed to interpret the form of the power spectrum, and to enable the low frequency white noise power of that spectrum, to be related to a local current density. The technique was extended to the study of aluminium pitting corrosion and the stress-corrosion cracking of high strength steel.

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