I have solid polymer membrane. Most of the lab has no for solid zeta potential measuring components. They told me only solution allowed. How can I measure zeta potential of my membrane?
Zeta potential is a property of a material in contact with an electrolyte, and will depend on conditions such as salt concentration and pH.
Typically, zeta potential measurements are usually performed for dispersed materials, i.e. colloids, but the zeta potential of a surface can be measured in a similar manner.
The following link describes this type of measurement and gives links to some useful resources including a paper on the technique.
https://www.materials-talks.com/blog/2015/01/06/surface-zeta-potential-what-it-is-and-how-to-measure-it/
Wondimagegne A Mo
In addition to Alex's excellent answer above, I'd be interested in your understanding of why one would want to measure the ZP of a membrane. How does that help you in your research?
Alan F Rawle , thank you for your critical comment. I think it will help to know electrical behavior at different mediums (cationic , anionic or amphoteric ). So, it will help me to decide the pH of the medium at which my membrane could have needed electrical behavior (cationic or anionic exchange membrane). This is what I know, if any further explanation, I need your help. Additionally, even Alexander gave me very good explanation as you support, I didn't understand. Still I am in need to know how solid membrane measured. Thank you
Hi Wondimagegne A Mo
Did you look at the references given at the bottom of the page I gave you a link to?
Amongst them is a paper describing the technique. A surface of interest, i.e. your membrane is attached to a custom dip cell, which is placed in an electrolyte solution containing probe particles.
Laser doppler electrophoresis measurements are performed on the probe particles, with the membrane at a range of distances from the detection volume.
A linear extrapolation of the probe particle zeta potential as a function of distance can then be used to determine the zeta potential of the membrane.
This technique is available on the Zetasizer range of instruments.
Dear Alexander, thank you in advance. I think you are suggesting me the experiment available: https://www.youtube.com/watch?v=Yj1FjsPWH74. But, most of the labs in my university they do not have sample cell as seen in the video. What they do is measuring dissolved solution in cuvette. Even they said we did not do for solids. Some people suggested me to dissolve the sample and measure the potential, but my membrane can not be dissolved in any mild condition. It need very strong reagents. Maybe this can also damage the cuvette. Thanks
You need to do streaming potential. It also measures zeta potential. This is an example: https://www.anton-paar.com/corp-en/products/details/electrokinetic-analyzer-for-solid-surface-analysis-surpasstm-3/
Electrophoresis is NOT the way to do want you need.
Streaming potential and electrophoresis are closely related. They are examples of electrokinetic phenomena:
https://en.wikipedia.org/wiki/Electrokinetic_phenomena
Read this for useful overview:
https://wiki.anton-paar.com/en/zeta-potential/
' to know electrical behavior at different mediums (cationic , anionic or amphoteric ) '
Often it is better to measure in a more direct way, in your case capacity to exchange ions or adsorption behaviour (binding capacity).
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