NaOH precipitation? !
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Is the precipitation in the NaOH storage tank caused by a reaction between NaOH and CO2 in the air? At room temperature, 10% NaOH solution. Thank you. . . .
Sodium hydroxide and sodium carbonate both have high solubility; at this concentration, no precipitation will occur during this season. It could be hydrogen and oxygen; the sodium oxide is not pure, containing trace amounts of calcium ions, and in this case contact with air may lead to the formation of calcium carbonate precipitates.
Indeed, a precipitate formed, but it disappeared after stirring! !
1. Is the sediment on the surface or at the bottom of the tank? 2. Could the sodium hydroxide solution contain aluminum ions?
The so-called alkaline sludge is likely to be calcium carbonate.
I’m not really sure whether there are aluminum ions at the bottom of the tank, because the quality of our alkaline solution isn’t very good, haha. . . .
The sediment at the bottom is colored; what color is it, do you see? !
Has the tank always contained NaOH?
The quality of your alkaline solution isn’t very good; it contains impurities! ! ! ! ! ! ! ! ! !
Use salt and acid to lower the pH value to 11, 10, 9, 8, 7, 6, 5 respectively, and see if any precipitation occurs Use sulfuric acid to lower the pH value to 11, 10, 9, 8, 7, 6, 5 respectively, and see if any precipitate forms Intentionally add an appropriate concentration of sodium carbonate to the solution to see if any precipitation occurs Observe what color the precipitate is.
Sodium salts are all soluble in water; there should be no precipitation of sodium salts. It could be other solid particles or heavy metal ions that cause precipitation. If it has a color, I’d like to ask one more thing: what is the color of the solution itself? ?