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What is this precipitation
Ingredients
10% STPP
0.2%% sodium hydroxide
Water
First dissolved STPP in hot water and it was stable, then when added sodium hydroxide in 20% solution form, it became cloudy, produced some foam and next day precipitated like this photo. What is causing this precipitation?
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2 Replies
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@Abdullah It’s been a while since I worked with it but isn’t STPP more soluble in cold water than in hot?
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I made two samples, one 10% STPP in hot and one in cold water. The one in hot water dissolved properly with low speed mixing but the one with cold water STPP didn’t dissolve until i heated it a bit.
These samples were made in glass pot. Surprisingly this time after adding sodium hydroxide, it didn’t precipitate.
Also, after adding 10% STPP in water, pH was around 7. Is it normal?
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