Talk:Peptization
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TMA
[edit]"In the synthesis of titania (titanium dioxide) nanoparticles, peptization involves adsorption of negative tetramethylammonium hydroxide (TMAH) molecules on the titania surface. This causes the surface to become negatively charged. Electrostatic repulsion of the primary particles in the agglomerated titania breaks up the agglomerate into primary particles.[1]"
- The article contains the phrase, "adsorption of negative tetramethylammonium hydroxide (TMAH) molecules" which doesn't make sense to me considering that TMAH is a salt (both a cation and anion). Does "negative molecules" refer just to the hydroxide? Perhaps this can be rephrased to be more clear. — Ed (Edgar181) 10:56, 4 October 2008 (UTC)
- I also note that the reference given makes no mention of use of TMAH to peptize titania suspensions. — 129.215.149.97 (talk) 15:02, 26 March 2009 (UTC)
- I had just the same reaction than both of you. The explanation given here above make no sense, because most of solid minerals suspended in aqueous solution are negatively charged in nature under normal pH conditions, except under acidic conditions when pH is below their point of zero charge (pzc). Finding a way to modify the surface charge of solids in contact with water at neutral pH or under slighly alkaline conditions to render it positively charged is always tricky (anionic getter). At the contrary of what was stated, a quaternary ammonium group, if attached to a surface, could make it positively charged. I propose to modify the sentence in this way. However, my thoughts given here are only a general and deductive reasoning. I have to confess that I have not read the paper mentioned in the reference.
"In the synthesis of titania (titanium dioxide) nanoparticles, peptization involves adsorption of a quaternary ammonium cation on the titania surface. This causes the surface to become positively charged. Electrostatic repulsion of the primary particles in the agglomerated titania breaks up the agglomerate into primary particles". — Shinkolobwe (talk) 10:05, 23 May 2010 (UTC)
References
[edit]- ↑ Y. Li, T. J. White; Lim, S. H. (2004). "Low-temperature synthesis and microstructural control of titania nano-particles". Journal of Solid State Chemistry. 177: 1372–1381. doi:10.1016/j.jssc.2003.11.016.
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