During the first days of bioactive glass immersion in SBF, ph measurements show a decrease of the pH of the solution. What may be the reasons for this drop in pH when bioactive glass comes into contact with SBF?
Hello Ms. Gaud
It happens because of ion-exchange reactions between the glass surface and the SBF medium. Ions like Na+ and Ca2+ are leached from the glass into the medium, while H+ ions from SBF react with Si-O- bonds from the glass surface, which means that H+ ions are consumed from the medium. Therefore, these coupled reactions yield an increase in the pH of the SBF solution.
Roger Borges Thank you for your answer, but my problem is that in my case I have a decrease of pH instead of an increase on the first days and days after the pH increase but very little... Have you ever encountered this problem?
Roger Borges The glass composition is : 38% SiO2, 4% P2O5, 29% CaO, 23% Na2O and 2% CaF2 (mole percent).
You may want to check: C. M. Queiroz, S. Agathopoulos, J. R. Frade, M. H. V. Fernandes, "Network connectivity and bio-mineralization of 0.45SiO2-(0.45-x)MgO-xK2O-0.1(3CaO⋅P2O5) glasses", Materials Science Forum, Vols. 455-456, 2004, 383-387.
Article Network connectivity and bio-mineralization of 0.45SiO2-(0....
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