Hi

You can disperse TiO2 Nanopowder in water-containing sodium hexametaphosphate (SHMP).

You can get more information by checking the link:Article Study on Dispersion of TiO 2 Nanopowder in Aqueous Solution ...

Ikeoluwa Apata

If it's a powder, it's a laser diffraction, not a DLS measurement.Sodium hexametaphosphate ('Calgon') is a (charge/electrostatic) stabilizing agent employed to prevent re-agglomeration in the series (wetting-separation-stabilization) of making a stable dispersion from a powder.

Note that the density of TiO 2(~ 4.2 g/cm3) means that any > 1 or 2 micron material will settle quickly and interfere with a DLS experiment. You can try huge amounts of ultrasonic energy to disrupt the sample but you're altering your material and contaminating it with the ultrasound probe.

There are slides (29 onward) on TiO2 and Calgon stabilization in this webinar (registration required):

Dispersion and nanotechnology

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat

You can get the imaginary and real parts of the RI for rutile, anatase, and brookite (the 3 most common forms of TiO2) from Palik or Dana. The wavelength is important and the materials are trirefringent.

In addition, keep in mind the pH-dependent surface charging of TiO2.

Article pH-dependent surface charging of metal oxides

Thanks for the answer Amirheshmat . If am to dispersed the TiO2 in water-containing sodium hexametaphosphate what will be the DLS parameters of dispersant like viscosity and dielectric constant.

Hello Ikeoluwa Apata - for the viscosity and dielectric constant just use the same as water, since you probably have so little hexametaphosphate in the sample, that the viscosity is the same as for just water. The dielectric constant will only matter for electrophoretic light scattering (zeta potential). Check the data quality, to make sure the sample size is not too large for DLS. Absorbance is not needed for making a measurement, only when converting to a volume distribution.

https://www.materials-talks.com/blog/2014/08/05/faq-how-important-are-refractive-index-absorption-for-nanoparticles/