We have used a simple sonication for 5-10 nm TiO2 in water - just put a tube with your sample to ultrasonic bath for 30 min. Then you will have a white solution - it is suspension of nanoparticles. About an hour the particles will be deposit on the bottom of the tube.
If the sonication in a bath will be not enough, it is possible to use probe ultrasonic disperser.
Thank you so much all of your suggestion.I have tried to disperse TiO2 nanoparticles in water.I used PEG 1000 as a surfactant. After one hr ultrasonic bath,I have found that all the nanoparicles are deposited on the bottom of the biker.How can I solve it?
PEG 1000 is not a surfactant. Depending on concentration it might increase viscosity slowing down settling velocity. If you still have a large percentage of mikron particles they should settle very fast (Stokes law).
Thank you so much Dr. Titus Sobisch.Could you please suggest me which concentration of polyphosphate will be suitable for the good dispersion of TiO2 nanoparticles?