I have done an experiment in which I add NaOH (pH=13) to water (within a maze geometry). When I use pure water as solution, NaOH diffusion through the maze is too slow (almost nothing) while if I use water+ anionic surfactant (with concentration well above its CMC), NaOH diffuses in an almost reasonable rate. I need to find out why the diffusion is different in the presence & absence of surfactant?
The only thing that I have found so far is "salting out effect".
Anybody has an idea?
Did you study the NaOH diffusion effect with a particular anionic surfactant, or several different such anionic surfactants ?, if so, what are the critical (minimum amount of surfactant )concentrations of each at which this enhancement is observed?, if the critical conc. is independent of the chemical nature of surfactant used, some physical interactions independant of chemical nature of species involved may be operating.
I suggest you collect as much data as possible, and use statistically designed experiments to obtain meaningful inferences about the process. It is an interesting work, good luck to you.
Dear Sara,
Both surfactant micelles and NaOH ions influence each others' diffusion rates by electrostatics. Please look at this article for a detailed description of the phenomenon: Article Diffusion of ionic micelles in salt solutions: Sodium dodecy...
I hope this helps. Kind regards, Leo
Debopam Ghosh
Dear Debopam, Thank you for your reply, Actually, I am using just one surfactant which is SDBS in conc. of 7mM,
Leo Vleugels
Dear Leo, thank you very much for the attached file, I'll read it
Sara Zarghami
Your question is interesting for my theory of micelle formation. I am interested in the fact that the diffusion of NaOH in the presence of surfactants after CMC increases.This is consistent with our theory. Usually the number of particles increases and diffusion should slow down. You can read the theory and practice of micelle formation in articles
Article Liquid Polyamorphous Transition and Self-Organization in Aqu...
Preprint Quantum entanglement in micellar solutions of ionic surfactants.
First of all, you must know what diffusion you measured and on which instrument. Apparently diffusion of ions. The diffusion of particles and ions is measured by the DLS method, and then, according to the Einstein-Smoluchowski equation, they are converted into the hydrodynamic diameter of the particle. Read
Article Structure of Micelles of Sodium Dodecyl Sulphate in Water: a...
Yuri Mirgorod Thank you very much Yuri, it's perfect if my observation is consistent with your theory, I should read the papers you linked. Thank you
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