How to find Refractive index and absorption coefficient which are required to do particle size and zeta potential test for 0.3 wt% of Cu, Ag, CuO, and MWCNT nanofluids. Each single nanofluid will be prepared in 0. 8 wt % aqueous solution of SDS.
Dear Dr. Nashed,
You can purchase a refractometer that will definitely be helpful to you in your zeta sizing /zeta potential analysis. Or you can go to Malvern website and download the list of materials they have and use RIs and Ab coeffs given for individual metals/chemicals.
Be careful of using SDS however, because you should not have any bubbles in your samples. If you do this will cause problems with the readings. The laser will reflect/refract off the bubbles and you will not get good usable data.
I have found that if you have a reasonable RI, you can get decent data with the Ab Coeff used from Cu, Ag, C. Make sure your solution is dilute enough for the system to resolve the particles.
Another alternative is hyperspectral imaging. You can view the instrumentation for CytoViva which can resolve nanometer-sized particles using reflective light.
Hello Dr. Nashed, If you use dynamic light scattering (DLS) as the sizing method, the refractive index of the material is not needed when reporting the intensity size distribution. The refractive index only becomes important when the intensity based result is converted to for example a volume distribution.
http://www.materials-talks.com/blog/2014/08/05/faq-how-important-are-refractive-index-absorption-for-nanoparticles/
http://www.materials-talks.com/blog/2014/01/23/intensity-volume-number-which-size-is-correct/
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