If you have solid particles bearing surface electrical charges in water, then you have an initial zeta potential value, evidenced when you apply an electrical field to the dispersion. The initial zeta potential value of may be modified if you add ionic species to the dispersion. The zeta potential modification results from the distribution of ionic species in the electrical double layer surrounding the solid particle, in others words; the addition of ionic species modifies the electrical double layer structure (thickness, ionic strength, surface charge density, etc).

The question is very general. You should specify the system. Aamane Jada is right, however, what if there is some specific adsoprtion of ions on the surface of the particle? Just give more information about your system.

I carried out some experiment using Egg shell membrane (ESM) as template. Initially, Nickel precursor (Acetate, Nitrate, and Chlorate) stock solutions are prepared. Then the ESM are immersed into the 3 above stock solution. After collecting the ESM from the solution, it found that the ESM are absorbed the Nickel metal ions. These ‘metal ion absorbed ESM’ are calcined to obtained pure NiO.

The elemental analysis of the above NiO reveals that the amount of final product from the 3 stock solutions varies (even though the initial amount of precursor salt and the amount of ESM are fixed constant). Hence, it is expected that the zeta-potential play a crucial role for the amount of the Metal ion uptake into the ESM.

That’s why I am curious to know about the variation of zeta potential for these three precursor solutions.

It is important to note that the ESM has a porous network structure, and also it consists of glycoprotein matrix and the collagen core which has form the –COO- and the –NH3+ charge network.

Thank you for the elucidation. As far as I understand the ESM is a protein membrane with porous structure. According to the books the charge of the proteins depends on pH of the solution. What can I advice is to measure the streaming potential of ESM at different pH and constant ionic strenght - let us say with NaCl (e.g. 10^-4 M). I suppose that the pH in your case is quite low because of the specificity of the Nickel species. Your system is quite complicated. You have negative and positive charges in ESM in the same time. Your anions are attracted by the positive charges, but the additional London interaction depend on the type of the anion. It is very possible due to this additional van der Waals interaction the porosity of your ESM to be affected and hence the access of Nickel ions to the internal part of the ESM. Try to separate the investigation to smaller parts and assembe the puzzel.

If the initial amounts of precursor salt and ESM are fixed, then one of the reasons for the variation of the Ni uptake is the variation of ionic strength of the precursor (Acetate, Nitrate, and Chlorate) stock solutions, which in turn will affect the zeta potential of the ESM. In addition the various structures of anionic species (acetate, nitrate, and chlorate) of the precursor stock solutions will affect also the ionic distribution at the ESM-water interface (i.e. the adsorbed amount of the precursor at the ESL-water interafce will depend on the nature of the precursor). It should be noted that the ionic strength in the presence of each precursor (acetate, nitrate, and chlorate) stock solution is function of the concentration and the valence of each ionic species constituting the precursor.

Thank you all for your precise explanation. Would you please kindly explain with an example how the valence of each ionic species varies ?

Each ion is having its isoelectric point . So the precursor is differ for same metal but of different salts, contribute to your zeta potential of the solution.