Anodic chlorate formation on platinized titanium

Abstract

The mechanism of anodic chlorate formation on platinized titanium was studied under well-controlled forced-convection conditions identical to those of previous experiments with graphite. Experimental results obtained in 4 M NaC1 and in 0.05 u NaC1 were compared to those predicted by mass transfer models describing anodic chlorate formation on graphite. In concentrated NaC1 solution anodic chlorate formation rates for both electrode materials are smaller than expected for a diffusion controlled process. In dilute NaCI the ratio between measured rates and those predicted for diffusion control is shifted to higher values in qualitative agreement with predictions. Quantitative differences observed between the two electrode materials were attributed to the fact that hypochlorite oxidation on platinized titanium did not proceed at limiting current because of the slowness of the heterogeneous oxidation reaction.

Electrosynthesis of Chlorate in the Nineteenth Century

“…From the observation that chlorate is never formed without the presence of hypochlorite he followed that chlorate is always generated from hypochlorite according to 2C10--5 OH---> C1Oa--5 H + -5 C1--5 2e-while hypochlorite is formed "secondarily." From today's viewpoint the reaction cannot be considered valid since the concentration of OH-in the bulk is usually small and its rate of diffusion toward the anode is negligible (27), but it is to Wohlwill's credit to have first given a formula for anodic discharge of hypochlorite to form chlorate and chloride.…”

Can Telluric Acid Replace Chromate as a Homogeneous Catalyst in the Chlorate Process?

“…A challenge in the chlorate process are side reactions causing parasitic oxygen evolution. O 2 is formed through the homogeneous decomposition of hypochlorite to oxygen (Reaction 2), [6,7] the direct anodic oxidation of hypochlorite (Reaction 3 and 4) [8][9][10][11][12] and anodic water oxidation. [13,14] Unfortunately, these reactions produce significant amounts of oxygen which mixes in the undivided cell with the hydrogen produced at the cathode.…”

Огляд: Вплив Природи Матеріалу Електрода На Анодні Процеси У Хлоридних Розчинах

“…The vast majority of studies are devoted to the study of the reaction of chlorine evolution in highly concentrated (1-4 M) NaCl solutions on the surface of electrocatalysts based on ruthenium oxides, iridium and other oxides. In those works where the kinetics of the formation of active chlorine and chlorate are studied, authors often rely on already existing mechanisms of chlorine evolution [73][74][75][76]. This approach is largely justified, because the formation of chlorine, on the one hand, in some mechanisms is considered through the formation of intermediate oxygencontaining chlorine(+1), and on the other hand, the formation of hypochlorite is considered as a result of interaction of molecular chlorine with water in neutral (23) and hydroxide ions in alkaline (18) media.…”