hey guys
recently i synthesized iron oxide nanoparticles by chemical co-precipitation,and the particles was capped with oleic acid . after i washed the slurry with di water and ethanol , i put it on a hot plate with a temperature around 70 celsius for 12hr to evaporate the ethanol .
however, it didn't get dry like a powder .
i need the powder so i can run XRD or SEM test.
So , is it necessary to put the slurry in a "vacuum oven" instead of hot plate or normal oven ?
Dear Yu-En Liu,
I don't understand Your problem. For XRD You don't need dried the sample - if it is crystalline, then it will be good looks on the XRD pattern even in the presence of the solvent. At the same time, to prepare a good sample for SEM You have to dilute the colloid solution to observe the individual particles. That is, for SEM and XRD studies You don't need have completely dried sample. From the other hand, if You need to study the stability and re-dispersing of prepared nanos, then You have to use the vacuum oven, then re-disperse the sample and do any other iterations...
With kind regards,
Liliya.
Generally, back when I was doing this, I would prepare a fairly dilute solution (At the very least, sufficient that it is partly transparent at ~50mL volumes) and then dry maybe 7 μL or so onto a surface for TEM or SEM imaging.
It can be very difficult to work with the dried powder, and it is also less protected from oxidation as a dry bulk material. I wouldn't recommend placing it into that state unless you very much need to. If you do need the whole thing dry, this can be done by either vacuum drying as you suggested, or re-suspend into a very volatile solvent and allow it to evaporate gently. Despite the intense heat involved in SPION synthesis methods, the final product can be a bit heat sensitive so I wouldn't recommend heating them excessively. If they are capped with oleic acid, then hexane should suspend the particles effectively and you can easily dry it off with small amounts in a well vented container.
You can put the material in a watch glass and dry it in an oven at approx. 70 degree for 6-8 h. Hot plate is not a good choice.
first, you have to wash the nanoparticles with the distilled water remove the impurities, then collect the NPs using a permanent magnet. Now you can put it into the oven at 90C for 24 hours.
I had the same problem. I got a high viscous gel instead of powder! After doing a lot of experiments, I realized that was due to the presence of extra oleic acid that hasn't been purified well. The best way to remove extra oleic acid is by using acetone and centrifugation.
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