I would like to prepare a suspension of ZnO and Fe2O3 nano particles to know their particle size distribution and zeta potential. I made a suspension with the help of water, but it has not gave desired level suspension. Settling (Agglomeration) was observed with water. Whether I should go for ethanol as a medium? will u suggest any medium to make a complete dispersion?
It may helpful if you use a polymer surfactant (PVP or PVA) while preparing the ZnO and Fe2O3 nanoparticles. Polymer coated nanoparticles should be water as well as ethanol dispersible. I tried it in my lab and i got success.
I prepared nano particle with CTAB as a surfactant. Even though, I observed agglomeration.
Give me a correct protocol sir
That's good.
You can also try with PVP. Here's a article in this regard.
Low aggregation can be obtained using steric stabilisation and non-polar liquid.
(modification with fatty acid and phase extraction with toluene instead of centrifuging)
Article Synthesis and testing of ZnO nanoparticles for photo-initiat...
Article Tuning the relaxation behaviour by changing the content of c...
To not use a surfactatnt if you want to measure the zeta potential of the oxide as material.
the use of surfactant will modify the zeta potential of ZnO and Fe2O3 nanoparticles. If you want to determine pure zeta potential of these particles it may not lead to. you can reduce the concentration and sonicate for longer time. for zeta potential measurements if the particle size is less than 50 nm the concentration must be reduced in order to reduce the agglomeration. However the agglomeration will remain and thats what your actual particles behaviour is.
seems that amount of CTAB is too low to give restabilization after turning the surface hydrophobic.
By the way result of particle size distribution and zeta potential will always reflect the actual state of particles, whatever you do to prepare and disperse them.
For the ZnO, it is a pretty broad question.
It often depends on fabrication method since they leave open molecular ends on the particle (PO4, Ch2, CH3, COOH, etc...). Solgel method often allows for long term stability with nanoparticles < 20 nm. The other problem is the size of the nanoparticles. Smaller distributions are stable for longer times.
Solution does matter and Ethanol does allow for longer stability. However, not long term stability.
As mentioned in a previous comment, surface treatment can stabilize ZnO, but zeta potential will change.
Homogenization with glass or Al macro beads for 24 hours creates solutions which are stable for several days, but leaves Si and Al coatings on the surface (which will also affect Zeta potential).
I would suggest just using 1 hour ultrasonicating in temp. controlled sonicator (higher temps will cause ZnO to grow and change properties), waiting 3 - 4 hours, collecting the dilute (mostly smaller particles) solution near the top, and immediately doing zeta potential measurements. Those types of solutions are stable for a couple days before aggregation becomes really significant.
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