What are the requirements for the concentration of potassium K ions in the chlor-alkali process?
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If a high potassium ion concentration affects the purity of NaOH, what methods can be used to reduce the potassium ion concentration in the electrolyte?
K+ cannot leave in saltwater, so it is inevitable that K+ will be present in the caustic soda product. The difference between Na alkali and K alkali is that the raw material is changed from NaCl to KCl.
The potassium ion concentration in ordinary raw salt is not high, unless it comes from raw salt materials derived from salt lakes with high potassium content. Since the price of potassium chloride is much higher than that of sodium chloride, brines with a high potassium content generally have potassium chloride extracted very thoroughly. Potassium ions have no effect on electrolysis; they merely cause the concentration of potassium hydroxide in caustic soda to be slightly higher, but this does not reach a level that affects quality. Is the potassium chloride content high in the raw salt used by the poster? If it is very high, the additional value of potassium chloride may not be lower than that of caustic soda; in that case, potassium chloride should be separated first. Potassium chloride is very expensive.
Thanks for the suggestion. The purity of our crude salt is not high; we want to purify it first. However, the concentration of potassium ions is also not very high, so it seems that there isn’t much value in purifying it separately. As long as it doesn’t cause any problems, that’s fine!