Recently, I did some experiments where I found that the negatively charged colloidal particles (diluted with water) strongly adsorbed on the glass and mica surfaces. Can anybody give me an idea of how a negatively charged particles adsorbs on a negatively charged surface?
Hi Nasima,
In principle this is possible, when a particle has a special "chemical affinity" to the surface. In this case, the chemical binding is energetically preferrable and powerfull enough to overcome the elecrostatic barrier. Such particles are called specifically adsorbed particles.
I can advise you a big publication, where you can find some information on that (DOI: 10.1016/j.cis.2009.09.004).
Can you give examples on your systems? Which surface and particles and what is the charge?
Thanks,
Kirill
Ok, 3rd try, some problems with my tablet...
what is the quality of your water, which pH does it have, why are you not using a buffer, eg ammonium acetate?
have you considered the counterions to your charged NPs?
maybe you still have some NP building blocks present in your sample that behave differently than your actual NPs?
Maybe one of these things can explain your problems...
Thank you all for your valuable suggestions.
My system (vesicle) was composed of sodium N-lauroylsarcosinate hydrate, 1-decanol and water (deionized water) and the zeta potential value is -42mV.
likely the glass and mica get hydrophobized first then leading to additional adsorption not governed by electrostatics. Some hydrophobic surface contamination might play a role or simply interaction with the decanol?
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