I would start with 1 % m/m, but you will have to test a range of concentrations.

A lot of different dispersants are in use, e.g. inorganic, polymeric. You should go better through some basic literature or info available at the net.

The "rule of the thumb" for alumina is 0.5-1 wt% with respect to solids at a particle size of ~ 0.5  µm. The surface of the particles has to be covered. The finer the powder the more surfactant you need and vice versa. You can identify the required amount very accurately by rheometry, zetapotential and particle size mesurement.

Dear Dr. Titus,

Thank you for your comments. Much appreciated.

Dr. Frank,

Thank you for the advice.

The surface area of alumina particles is approx. 2.95 m2/g. My powder has around 100 times larger surface area than alumina. I'll follow your concept of the finer the powder - the more surfactant I'll need.

Thank you also for having mentioned here the techniques to be used in such situation.

Best Regards.