ZnO nanoparticles do not sediment properly in centrifuge?

[goggles31]

I centrifuged my sample at 9000 rpm for 30 minutes. There is a layer of sediment on the wall but if i tilt the centrifuge it comes off the wall.

 

[jim mcnamara]

For starters:
What is the viscosity of the liquid? And what liquid is in the tube?

... assuming they truly are nanoparticles - because people have been misusing that word a lot.
There can be electrostatic problems for example.

Someone here may know the standard procedure for this separation.

 

[Bablu]

can you give me the name of liquid?

 

[quackyneudle]

Are you trying to precipitate your nanoparticles by injecting a poorer solvent? If that's the case, there could be a few reasons why this is not working. If the particles are too small, then even if they are in a poor solvent they may not precipitate. If the solvent is not bad enough, that will also cause this. In my experience, loose precipitate generally means that there is other "stuff" in there that is keeping the particles from forming a tighter pellet. Think about what other compounds there are and how they will interact with the solvent(s).