Dear Praful Damdar, dissolve or disperse ? Dissolution is easier in acid medium. My Regards

After preparation, Metals oxids need to be dispersed to dissolved and it can be dispersed in water by water bath sonication for nearly 10-15 min.

Dear Praful,

You will find a few (hundred) reponses to similar question within Researchgate. I think its obvious that you do not want to solve the ZnO.

Think about:

What is your challenge - ZnO as filler, ZnO as catalyst, for sun protection, ....

What kind of ZnO do you use (size, commercial, self coprecipitated, …)

If you like to do nanoparticle or photo-catalytically active material take a look on my publications.

I also cited the review article of Hoffmann and Hoffmann which will help you in your search.

If you like to use it as filler material take a look at web-sides like byk or Rahn where you will find suitable surfactants.

If you are trying to *disperse* ZnO particle in water, sodium hexametaphosphate is very effective. You should also adjust the pH of the water to be approx 9. ZnO dispersions are slightly alkaline (8.5) and near to the isoelectric point. Raising the pH increases the surface ionization.

Dear Praful Damdar thanks for sharing this technical question with other RG members. As already indicated in the previous expert answers, nanoparticles in general (including ZnO NPs) cannot be dissolved, but only homogeneously dispersed. Of course you can dissolve your ZnO nanoparticles in aqueous HCl, but then you have a clear solution of ZnCl2 and the ZnO NPs are gone! I strongly suggest that you use RG directly as a valuable source of information. Just search RG for terms like "ZnO nanoparticle dispersion" and then click on "Publications":

https://www.researchgate.net/search.Search.html?type=researcher&query=ZnO%20nanoparticle%20dispersion

Good luck with your work and best wishes, Frank Edelmann

This is a copy of my post to

https://www.researchgate.net/post/Which_solvent_should_I_used_to_dissolve_graphene_oxide_nanoparticle

Before to discuss whatever we must define the terms used in the discussion. Are nanoparticles dissolved or dispersed. Is a dispersion homogeneous or heterogeneous?

Definitions recommended by IUPAC

Homogeneity. The degree to which a property or a constituent is uniformly distributed throughout a quantity of material. A material may be homogeneous with respect to one analyte or property but heterogeneous with respect to another. The degree of heterogeneity (the opposite of homogeneity) is the determining factor of

sampling error

Colloidal dispersion. A system in which particles of colloidal size of any nature (e.g. solid, liquid or gas) are dispersed in a continuous phase of a different composition (or state). The name dispersed phase for the particles should be used only if they have essentially the properties of a bulk phase of the same composition.

Solution. A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. When, as is often but not necessarily the case, the sum of the

mole fractions of solutes is small compared with unity, the solution is called a

dilute solution. A superscript attached to the ∞ symbol for a property of a solution denotes the property in the limit of infinite dilution

Dissolution. The mixing of two phases with the formation of one new homogeneous phase (i.e. the solution)