Hello! Currently, I'm researching a coating made of AgNP/silica. I conducted a durability test where I immersed a glass slide coated with this material into various pH solutions, such as pH 3, pH 5, pH 7, and pH 9, at room temperature. Surprisingly, around 70-80% of the coating dissolved after 3 days in the acidic solution (pH 3), while there was less dissolution in the alkaline solution (pH 9).
According to the literature, dissolution rates should be higher in alkaline solutions compared to acidic ones. However, in my experiment, it was the opposite. Strangely, I observed a higher dissolution rate in the alkaline solution at higher temperatures, as expected. I am seeking any clues or explanations as to why the AgNP/silica coating shows a higher dissolution rate in an acidic solution than in an alkaline solution at room temperature. Any help or insights would be greatly appreciated. Thank you very much!
Sn Pepe
If you have nanometer silica nanoparticles, then the size effect works for you, like all nanoparticles. You did not write what you are comparing the solubility with.
1. Under all equal circumstances, small nanoparticles dissolve better than large ones.
2. Your solubility depends on pH. Silica is amphoteric. It interacts with both acid and base. This is the second factor that affects solubility.