Theoretical and Experimental Study of Flow‐Through Porous Electrodes

Abstract

2 1 e with a calculated slope equal to 0.0295V instead of 0.0885V. Similarly, the defect Vcd' would give a slope equal to 0.059V.The hypothesis can be made that the plateaus observed in the titration curves are due to impurities introduced in the sample, either during the cadmium electrodeposition or during the formation of the sulfide layer. Particularly, the samples could contain cadmium oxide and/or sodium sulfide. As sulfide and oxide species are similar the presence of dissolved cadmium oxide (i.e., the replacement of a sulfur atom Ss by an oxygen atom Os) could only slightly modify the cadmium sulfide properties. Sodium sulfide is an ionic compound which dissolves in CdS with more difficulty. It is also possible that the remaining sodium sulfide is transformed into cadmium sulfide during the oxidation of the cadmium in excess. However, as it stands now, it is not possible to state precisely what kind of impurities are involved. But the obtained results show that electrochemical analysis is a possible method of studying cadmium sulfide and, more generally, semi-conductors having a possible deviation from stoichiometry.

Reacteur a electrode volumique a lit fixe: Taux de conversion et selectivite

“…Cette chute de potentiel entre le base et le haut d u lit poreux augmente avec plusieurs parametres d'etudes tels que la vitesse de percolation, la surface specifique (S,), la hauteur totale d u lit poreux et la concentration en ion argent. Ce phtnomene a d'ailleurs ete deja signale (Paulin et al (1977); ) pour d'autres systemes electrochimiques. Lexamen de cette figure montre egalement tout l'interet qu'il y a a tracer la carte de tension d'electrode au sein du lit poreux.…”

“…Plus precistment, les electrodes poreuses percolkes (E.P.P.) a lits fixes, possedant une grande surface par unite de volume peuvent assurer une solution originale au traitement de ces effluents et a la recuperation des metaux qu'ils contiennent (Bennion et Newman, 1972;Chu et al, 1974;Newman et Tiedeman, 1978;Olive et Lacoste, 1980;Paulin et al, 1977;Trainhman et Newman, 1977).…”

“…En ce qui concerne l'aspect physique du depdt, on est oblige, suivant la solution electrolytique et le probkme a traiter, de favoriser un regime de cinetique electrochimique. C'est ainsi que divers auteurs ont envisage le cas de systemes electrochimiques obeissant a des cinktiques d'activation pure , de diffusion (Paulin et al, 1977;Ratel, 1980), de diffusion limite (Coeuret, 1976;Olive et Lacoste, 1980). Dans le cas prksent, des etudes preliminaires, portant sur la qualite du dCpBt de l'argent present, en faible quantite ( S 100 p.p.m.)…”

Scale-Up of Electrochemical Reactors

“…Coeuret et al [56][57][58] were the first to study and analyse the current and potential distribution in flow through fixed bed by using a mathematical approach similar to that proposed by the chemical engineering discipline for heterogeneous reaction. They represented the current and potential distribution by the following dimensionless relationship:…”

Scale-up of a fixed bed electrochemical reactor consisting of parallel screen electrode used for p-aminophenol production

“…Coeuret et al [5][6][7] were the first to study and analyse the current and potential distribution in flow through fixed bed by using a mathematical approach similar to that proposed by the chemical engineering discipline for heterogeneous reaction. In their analysis, the following hypotheses are made:…”